Make a Joule Thief

Yes, it's the infamous Joule Thief, in Instructable form! For those of you who don't know, the Joule Thief is a tiny little circuit that allows you to drive a white or blue LED from voltages as low as 0.5 volts. You think those batteries are dead? Don't throw them out yet! Hook them up to the Joule Thief to squeeze every last drop of energy out of them!

The idea and circuit came from this Make weekend project. Why don't you pay them a visit?

Step 1: Parts and Tools

For this project you will need very few tools and parts, as you will see in the picture below.
But for those of you who like it in text, here it is:

Helping Hands (Optional)
Soldering Iron
Solder
A Blue or White LED (Other colors are fine, too)
2N3904 Transistor or equivalent
1k Resistor (Brown-Black-Red)
Toroid Bead
Thin wire, two colors (magnet wire works)

You can get the toroid and transistor from a dead CFL; the transistor is usually labeled 13002.

Also, if you use a 2N4401 or BC337 transistor, your LED will be brighter because they can handle more amps.

Comments

[ygupta1]

Okay I made one. But how do I make the LED brighter?

[123awsomelad]

Can you just use a straight ferromagnetic core? or does it have to be a toroid?

[adien gumilang]

yes i can, but i just curious, i found these on my small electric motor, then i think, can i substitute the toroid with this?
um.. forgive me, i just a beginner

[adien gumilang]

can i subtitute the toroid with the same-shaped magnet ?

[Jollyrgr]

Since I don't see it, I will add my two cents. The Base of the transistor connects to the resistor. The Emitter goes to the negative side of the battery.

[colin55]

Here's a Joule Thief you can make from a fridge magnet. And it flashes:
This bike flasher uses a single transistor to flash one or two white LEDs from a single cell. And it uses a fridge magnet for the core of the transformer. This means anyone can build it with common components.
Cut a small fridge magnet into four pieces and make sure each piece sits the same way on the previous piece. The size of the pieces do not matter. 1.5cm x 1.5cm works well. Now wind 30 turns and then another 30 turns. Build the first circuit and connect the wires. If the circuit does not work, swap the feedback wires.
Now add the 10u electrolytic and 100k resistor (remove the 1k5). The circuit will now flash.

[colin55]

circuit:
http://www.talkingelectronics.com/projects/200TrCcts/images/BikeFlasher-Amazing-1.gif

[rabitt]

hey man how i can conect 20 leds on this circuit....tnks

[rabitt]

hey man..what i nedd to change on this circuit if i want 10-20 leds....help¡¡

[m.halsey]

We made two and both aren't working. It's not the batteries, we tested on old and new batteries. We followed the instructions step-by-step. The only thing we can think of Is maybe the toroid coil wires? Is there a specific way the toroid coil's wire need to be to make it work? We have red and green soldered together and then the green soldered to the transistor and led light and the red soldered to the 1k resistor. 1st timer here. Thanks

[blakdragon19]

yes, for the two leads that you coil together, they must be one of each separate coil (using different colored wire for the two helps here)

[mtuks]

i'm making a JT currently with a wrrist watch battery and you won't believe it..i'm revolutionising energy!! :)

[colin55]

Here is a Joule Thief with 10 LEDs on a 9v battery

[colin55]

Here is a circuit for 10 LEDs on a 9v battery

[DHeigh]

I'm trying to fix a 3 LED, 2 D-cell flashlight, the LEDs don't light.
The circuit they are in has a 3-pin device labelled only "8N 11027" & a 2-pin device w/o any label.
I thought I might rebuild it with a joule thief that would work with 3 white leds off 2 D-cells. Can you help?

[stringstretcher]

How do joule thieves work with lemon batteries?

[1up]

Do you mean how well do they work? It certainly should work. You may need more than one lemon to get at least 1v, though.

[colin55]

(removed by author or community request)

[mittu gat]

Hi my transister is getting rlly hot!! but the led lights up. i hooked up 1.5v battery......

[ctudoran]

Hello!
Can anyone tell me if I can use this circuit to light 5 leds (3V), but from a 2.4V input?
Thank you!

[1up]

You can hook them up in parallel, but there may not be enough current to light them all very well. You could put resistors on each of the LED's so they only draw a few milliamps, but that may still be too dim. You should try and see.

[bludlow]

Is there any problems with using a 1.1k Resistor rather than a 1k resistor as i have only 910e and 1.1k resistors in that kind of area, thanks.

[1up]

That'll be just fine.

[alindsey3]

it should be fine, check the voltage coming out and based on your led choose a correct resistor needed to lower the voltage enough for the led

[ssuman1]

Hello will joule thief be able to light up n LED from salt watr

[jason10kv]

ssuman1,you can't light up a led from salt watr,because the miliampere is very small.

[jason10kv]

hello sillyscript! you could try connections an be sure that the enamel on the wire is removed.

[Sillycrypt]

Hey i made this with a BC337 transistor & a xbox toroid but i doesn't show any signs of working? what could be wrong! thanks

[buteman]

I have just built a joule thief following these instructions and it works well. I used a BC549 transistor rather than the 2N3904 as this is what I had. I used a toroid from a CFL bulb with 5 turns of wire. It will light 2 white LEDs wired in series so I tried using red LEDs in series and it would still light 10 of them in series although with that many they were not very bright!
I have seen lots of comments asking it a transistor type BCxxx 2Nyyy ( you get my drift ) would work.
I would suggest that anyone asking can easily find out quickly by using google search.
It needs to be an NPN transistor and if you search for say hsd965
you will find it is an NPN transistor. check which pin is collector, base and emitter and connect them as explained in this instructable.

The only time you might get a problem is if the gain ( Hfe ) is very low.
The hsd965 is quite high power and it's gain is high too.

If it still doesn't work then assuming you have all the connections made you should try reversing the connections for ONE of the wires. In the picture above for example swap the 2 orange connections over.

Hope this helps.

[echuzzzzcute]

can i use hsd965 for transistor?

[echuzzzzcute]

is it okay that I use 2n3035 for high amp?

[emcelhannon]

Can I prolong the life of 2 double A batteries that power a 3v motor?

[tylervitale]

Probably not. Joule thieves don't provide a lot of current. They work with LEDs because LEDs use very little current. A motor is likely to draw far more current.

[Malkaris]

I've been playing with this for a little bit and I've had 0 luck getting the LED to light with the setup explained. However, I put a 1uF cap across the 1k resistor and it worked.

I can't figure out what is could be different in my setup that requires the cap.

Any thoughts?

[nodoubtman]

Why should i use a transistor ?

[WildWalkerCT]

because the transistor will drive the toroid transformer by switchingon and off at 50 KHz

[sconner1]

Looking for a torroid?
Take apart a burned out spiral lightbulb.

[claymantoo]

Thanx 1UP!!!
I couldn't get it to work though until I removed the resistor.
Works fine without one.
It works with the said resistor if I put it at the beginning of the circuit, but of course the led is dimmer.
Nothing I tried otherwise worked.

What is the reason for the resistor?

I'm sure that Question has been answered before but I don't care enough look through 641 posts to find out.

Anyone want to take a sec to answer this?

I'm using a ferric torrid,
magnet wire,
<1.5v AA Batt.,
2n3904 transistor,
NO resistor???

[sconner1]

The resistor is to protect the base of the transistor from voltage spikes above the maximum rating preventing damage to the transistor.
It is Not supposed to be in series with the led like the usual job of current limiting.
With only 1 battery, going without the resistor (I hear) should work fine.

[dill1104]

I have tried 7 different times to build this, and I am getting nothing.  I started with #22 wire but could only get 6 wraps on my toroid (radioshack 10 pack)  I then moved up to using #26 and #30 gauge wire..still with no results.  I was using a 1.1k resistor (gold,red,brown,brown) and then switched to a 1.0k (gold,red,black,brown)  My transistor is the same as in this post.

Does the LED matter?  my toroid is about the size of a dime...is that big enough?  What size wire is best...is enamel okay to use?  Does it have to be a WHITE or BLUE LED?  I am also testing with a new AA battery

any help would be great! 

[1up]

I've gotten this from a LOT of people.

And I really can't figure it out, at all. :/

People always tell me they did everything right and it still doesn't work.
Assuming you have checked for shorts, etc, have you tried a different transistor? Maybe you burned it out.
You know the two wires coming out the other side of the toroid? You could try switching them.
After that, I'm not sure what to do. Maybe it's a thing with the toroid? Tell me if it's magnetic or not.

[yaja]

For me, scraptopower's idea of switching one of the windings around worked. Disconnect from res and and batt and reverse. Don't unwind. Thanks

[ifarhan1]

can we use this to charge mobile phone batteries? If can, how?

[1up]

No, it doesn't put out enough current. Plus, it's really constantly switching on and off, not providing steady power.

[ifarhan1]

what is the amount of current needed to charge mobile phone battery? can i use the transistor to increase the current? my idea is to connect the joul thief to my created earth battery. Can i?

[Winu]

i'm also interested of doing something similar... right now im trying to do a decent toroid and finding the right resistance for such application. I think that if you can add a capacitor to temporarily store the charge, it might help somehow.

However, to the circuit you might want to add a voltage regulator (say, an LM317 found in UPS systems) and with the use of resistors you can set a steady current at a specific EMF. For the voltage regulator setup to work you need a voltage input which is greater than your desired output so you probably have to tune your joule thief. The addition of a secondary coil to the toroid (to step-up the voltage) can be an answer.

I'm just a hobbyist with just an intermediate level physics. :P Research just got me better. xd

[Ray Power]

Thanks for the instructable! I could only get 4 wraps on my CFL salvaged toroide but it seems to work

[nodoubtman]

What is the role of Toroid here ?

thanks!

[ernie666]

I tried to make this circuit so many times with no LED lighting up. I figured that maybe the 1k ohm resistor had too much resistance, so I swapped it out with a 560 ohm resistor and surprisingly, it lit up.

[0151n]

Does it matter what the toroid is made of ?

[Vick Jr]

Does anyone know where the "8-11 turns" of wire comes from? Is this from trial and error or Is there an actual equation where you plug in the I/O voltages, current, frequency, inductance, etc. and solve for the number of coils? (I like physics and ideal models.) : ] Knowing a formula like this could also help people optimize for using different power sources, LEDs, transistors, and torroids.

[poza]

your question is a year old, to be sure, but i'm working on a somewhat similar electronics project and i stumbled across your question while looking for answers to my questions. i have no knowledge on this subject and i'm in the process of learning as i go. i found a formula that mentions the number of turns around a toroid. you might check this out: http://www.mantaro.com/resources/impedance_calculator.htm#toroid_inductance

[robot1398]

can i use a bc547 transistor in place of 2n3904

[-max-]

i used a transistor out of a flash camera, it worked. after playing a lot with it, i found the 2n3904 to be vastly superior. most other transistor didn't work or barely did.

[robot1398]

i made it with bc547 and works better than 2n3904

[-max-]

great for you! i dont know if half the transistors i used were NPN or PNP. i think most were PNP

[robot1398]

then how did u know the pinouts

[robot797]

all npn transistors work

when i build one
i get my junk box and desolder the firsth npn i see :P

also if you make the 1K resistor a 2 or 5 K pot you can tune it into the right frequentie

[robot1398]

thanks

[RONEDOGG]

i just tried this for a xbox 360 controller leds. and well it didnt go so well. i used the same size troid same transistor but my resistor was abit different. it was grey in color. and it heats up liek bad. enough where i have a blister on my leg where it fell. lol

any idea what transisotr to use for 4 LEDs?

[S33PlusPlus]

Sounds like you either shorted the supply rail to ground or overloaded something (the transistor can only dissipate 100mW or so, and the most abundant resistors are rated for 1/4W)

Which parts got hot? And is there a reason you need to drive the LEDs with a joule theif?

[RONEDOGG]

hello. you might be right. i did short out the transistor it started making a high pitch noise after.
it was the resistor that got hot. but i realized that after i forgot the battery on the xbox controller is 2x 1.5v.
i started over again and got it all working.

the reason for the joule thief is with wireless xbox 360 LED ABXY mods, when the battery gets under fully charged the LEDs in the controller dim really fast. and its noticeable after about 30 40 mins of using the controller on a fresh charge.

so i herd talk of people thinking of doing a joule thief in the xbox 360 controller. but no tutorials anywheres i could find. so i pieced this together myself. this joule thief tutorial and another for LEDs in the controller.

how i have it setup now is a 1k resistor from the controller to the joule thief + input. and the - to the joule thief to the - on the controller.

then on the +s and -s on the output of the joule thief i put 4 x 5mm white LEDs.

the batterys in the test controller are completely dead. cant even connect to the console for more then 2-3 mins. yet the LEDs for ABXY are bright.

when im saying + or - im referring to polarity. and my joule thief is using all the parts listed above. just put together abit neater.

[1up]

That's probably not a resistor, then. And you don't need this for XBOX controller LED's. The 360 controller already has a 3.7v battery, so you just need a resistor for your LED's.

[RONEDOGG]

yeah lol thanks i was having a slow moment the other day. i figured it out. i forgot to have a resistor coming form the controller to the joule thief. got it all working now.

i just put another 1k resistor off the controller + before the joule thief

battery life at 1 bar and the LEDs are still super bright. now just to fit this troid into the controller housing lol

quick question 1up. if i wrap the troid more then the recommended turns will this improve brightness for 4-6 LED's?

[1up]

You're not listening. :P Don't use a joule thief. The 360 controller already has a 3.7v source, which is plenty enough to drive these LED's. A joule thief is for when you want to run 3.3v LED's from a 1-1.5v source.

Just calculate a resistor for your LED's and use that in front of them.

[RONEDOGG]

yeah lol im listening. there is one factor your missing. when the battery pack starts to die. the 3.7v is no longer 3.7v its more like 2.0v. so the LEDs dim. i used the right resistor and it did nothing. when the battery's were under fully charged. the ABXY buttons would dim. then by the time the battery got to half, there was no illumination to the ABXY at all.

dunno maybe i am missing something big here. i dont know anything about what im doing but i do know is the joule thief did fix the dim ABXY LEDs lol

If you google around people talk about similar issues with DIY ABXY LED mod on wireless controllers. thats why they mainly do it on wired controllers. because if the battery's for the controller are not fully charged the LEDs are considerably dimmer

I am wiring my LEDs in the controller on the positive and negative leads inside the controller.

Not sure if any of this is making sense to anyone. but i can post pictures and show what im talking about. its clear to see lol

[S33PlusPlus]

More turns shouldn't make a huge difference. I made one the other day on the same ferrite core (Dead CFLs are handy!) with ~20 windings of 30AWG magnet wire and I didn't notice improvement over my 12 turn toroid.

[ajain7]

Can ferrite out of adapter, which is square in shape, work? I used it with transistor named 13001 and a resistor but it was not working at all.

[ajain7]

Can ferrite out of adapter, which is square in shape, work? I used it with transistor named 13001 and a resistor but it was not working at all.

[jensenr30]

the way the torid is configured steps-up the voltage, right?
Please explain to me what the torid does exactly. I really appreciate the time and effort you put into this project! Thanks for posting!

[jhao]

you could get a nice battery holder instead of soldering the wire straight to the tip of the battery :)

[ifarhan1]

Can anyone help me where can i find the toroid? is there anything that i can replace with the toroids? Another question is can i replace the toroids with round magnet? please help me :(........thanks

[Indula]

can we use button cell

[rstevens76]

I'll 2nd that - it'll explode. I've tried numerous times to solder button cells, sometimes I get away with it (and I'm a fairly decent solderer), but probably 80% of the time it'll explode. Of course, it usually doesn't cause any damage, just a loud pop and you'll need to change your undershorts!

[chitkaran]

Why dont u try using a Button cell holder.. ???

[zstein]

Cause "Cowboy electricians" think everything should be soldered directly onto... You're exactly right, that's why they make button cell holders.

[1up]

Sure, but don't solder to it. I can almost guarantee you it will explode.

[Gepetto Father]

i've soldered button cells many times with no explosions involved. What does happen is the fast oxidation of the metal case, specially where i sand to get a cleaner sodering surface.

Of course, don't take too much time soldering it or it really might explode. Other thing to note is that they stay hot for like, centuries, after you heat them.

[ShemySheza]

thanks but 1 question-how many wounds of wire?just 10 or can i use more?does it matter?

[-max-]

with most Joule Thiefs it doesn't matter. as long its more than 2 or so. the more windings you can fit, the better.

[jtod]

How can drawing power OUT of a battery charge it up.? I don't make sense to me.

[-max-]

the dead battery still has a lot of juice in it when it wont power up stuff around the house. the Joule Thief will take advantage of that power and charge another battery of course it wont have more charge as the first. as the law of conservation states.

[1up]

Where did I say this would charge the battery?

[axeman911]

whats a toroid what is its purpose?

[-max-]

yes. the finished toroid acts ( and is) a simple step up transformer.

[imarcianoloco]

A toroid is any donut-like shape. In this case, it's a toroid made out of ferrite (a ferromagnetic but electrically insulating material), which helps the magnetic field to flow better, thus increasing the efficiency of the Joule Thief, which is essentially a small transformer.

[ARJOON]

most difficult part was trying to impress my gf

[rayfalcon]

hey it works kind of! let me explain whats going on it blinks my led but will not keep it lit up and my battery gets extremely Hot so i quit using the one i just made and taking some time to try and get help on itthe 1 k trans might be wrong on mine its a clear glass thing with Brown black and red on it but its glass and on one side it says 48 thats all it has on it.....Is that a 1k trans or is this a diode? if so can that be the problem?
Charles

[its2l8men]

I think it's a zener diode

[1up]

It's a diode if it's glass. :P Look up some diodes and resistors on Google images so you can tell the difference.

[kcarring]

+maybe it is a 1n4147 diode. resister shouldn't be glass. if it looks like this: http://tinyurl.com/27l63z6 it's a diode

[caminokid]

I nice additional usage for these batteries. I had been using mine in small battery power clocks and my work ear muff radio. I accumulate quite a supply so will make a case for this unit so I can change out the batteries more readily.

[buju357]

My 4 x 20k mcd led torch:
h**p://buju357.blogspot.com/2011/05/very-powerfull-joule-thief-single.html

[rli3]

can we use a MOSFET transistor instead of the one in the pic

[balodabazar]

can i use a bc 548 transistor and connect this circuit to my mini wind turbine for more output voltage.......

[Alexdlp]

Hey, I'd just to say that I found this instructable really helpful when making my latest project... Hope you don't mind but I put a link and referenced your instructable in one of my steps ;)

http://www.instructables.com/id/The-Juicy-Lemon-Light-Pod/

Thanks!

[lukedwards]

Thanks for the explanation! I thought I knew but wanted to double check and your instructions are in plain English and very easy to understand. Wish some people would take a tip from you and include this in their instructions instead of assuming everyone winds toroids everyday.

[kenmneth]

its a game to keep people living in fear. i use this second computer for people that might play those games if infected i just go buy another one for one hundred dollars at the nearest pawn shop.

[kenmneth]

is it possible for you to call me at 603-606-1171 ken

[kgaurkhede]

hey 1up i have a gsl bc 1488 transistor ...
will it work?

[Coindude19]

Dude, this is one of the most awesome instructables I found. made one, and it works! thank you!

[jpagatpat]

How about if i used a bigger ferrite instead of the toroid bead? should I make more turns?

[batman96]

I just rebuilt the one I built a wile ago that didn't work and it works now, I am trying to decide to build a "dead battery flashlight" or a "dead battery night light"
Turns out the transistor I had was either broken or pnp. I got a bread board so I just tried different transistors until it worked.
Thanks for the very detailed instructions!

[chris28456]

Great Project. Anyone know what gauge (awg) wire is suggested? also solid core vs. stranded does it matter? Thanks

[lperkins]

It's perfectly possible to solder to batteries without any ill-effects. Commercial battery packs use spot-welding, and you want the heat characteristics to be as close to that as possible. Basically you want a high-power soldering gun. One of those little pencil irons is not going to cut it. In my experience, a good rule of thumb is to never put your iron to the battery for more than about two seconds, and then let it cool completely first if you have to hit it again. If you can't make it work that fast, you need a hotter iron. I can only speak for Alkaline, NiCd, and NiMh batteries. I wouldn't even try to solder things with "Lithium" anywhere in the name without good safety gear and a fume hood.

[robot1398]

i made it and it works very well.
i used a bc547 transistor

cool project

[spartans]

as the transistor turns on and off quite frequently wont it damage the LED being used.

[Munchys]

My led requires 3.5v this wouldn't be able to power it would it?

[Musicman41]

what is the purpose of the toroid?

[JoshuaZimmerman]

Wire wrapped in a coil creates a magnetic field when power flows through them (thats how electric motors work). In this case we get a magnetic field building up in the coil, when the transister switches the field collapses and the extra power it's build up gets flooded into the circuit. This then happens like 1000 times a second. This is how we're able to power a 3.6 volt LED off a 1.5 volt battery. To directly answer your question the toroid is just something for you to wrap your wires around, anything will do. I love using this circuit in combination with a solar panel to build weird solar lights. (I even have kits available for it on my website, browndoggadgets.com)

[Munchys]

So could I use a super magnet with a hole in the middle instead of a toroid?

[JoshuaZimmerman]

Just use a toroid. Or anything round really. A magnet might cause all sorts of issues, and be a big pain to work with around all these metal parts.

[PatrickVallieres]

i us a button cell and a hollther from a old computer and a micro swech

[thomas53]

Works perfectly :)

[rhanson294]

Not to be offensive, but I have always been told that you never solder to a battery. In some of the pictures it looks like the wire is soldered directly to the battery. Just wondering how safe that is.

[luiscll]

I think that with a pair of magnets the soldering can be avoided. Just an idea to who wants to avoid soldering.

[thomas53]

Or just use a battery holder

[threewheela]

its plenty safe as long as you dont overheat the battery because it could explode and everyone knows heat is bad for battery life anyway

[1up]

It does looks like that. I actually slid the wire under the plastic cover on the battery to hold it in place, and the bottom wire is just being sat on by the battery.

You are right, you should never try to solder to batteries.  

[beehard44]

just do it quickly and never using a button cell

[robot1398]

how thick wire we have to use to wind on the toroid

[scraptopower]

If you've built this and it doesn't work, try reversing one of the phases on the toroid. I built two neither of which worked. I read on another site that if it doesn't work but is drawing current (mine drew 50ma without lighting the LED) then one of the phases of the toroid must be the wrong way around. Now it draws 39ma and lights up the LED!

So I reversed one phase in both of my joule thieves, and they work brilliantly now! The LED is blinding!

Thanks for the great instructable!

[batman96]

I got Joule Thief I built that doesn't work, every part is good, I got a multimeter, how do I check if it is drawing any current? And if it is how do I "Try reversing one of the phases on the toroid."???
Thanks.

[1up]

Thanks for the tip! I think I'll add that with credits to you. It should help a lot of people. If I'm understanding this right, you just need to reverse the two wires coming out of the toroid (going to the transistor and resistor) and it should work fine?

[scraptopower]

No, I actually reversed one of the of the coloured wire completely. I took one of the wires from the end that was twisted and connected it to the resistor, and then I took the wire that was originally soldered to the resistor and connected it to the other wire that was twisted. So completed reversing one colour of the toroid.

This makes no sense why it worked, as the way you wound the toroid both the phases should be the right way. But it worked...

[1up]

How interesting... I'll have to give it a try if it doesn't work.

[yaja]

Scraptopower had it right. The idea of switching one of my colored wires around totally works for me. I went from dim or barely working to bright and using a dead battery.

[batman96]

From what I understand this is a simple transformer. So could you use something metal for the core, like a thick washer?

[1up]

Probably. You can even use air, or a rusty nail:
http://hackedgadgets.com/wp-content/_rusty_nail_led_project.jpg

[batman96]

Thanks, a couple of more questions though.
1) For doing it with the nail, do you go down the nail then back up with the wire?
2) In the image what does the Cap do?
3) How do you do it with air?
4) From what I understand the power going to the LED is AC, because of the on/off from the transistor, so could you run the power through a diode rectifier to run other stuff, or would you need some caps to make the current continual?

Sorry about having so many questions I don't know much about circuitry but would like to learn, and I thought this would be a good one to build.

[Dreistein]

how high is the voltage of the battery and joule thief?

[1up]

The joule thief puts out about 3.0v and will run on anything from 0.6-3.0v, depending on how well you make it.

[buju357]

see here how I made a 6 led joule thief torch.

h**p://buju357.blogspot.com/2010/12/6-led-joule-thief.html

[GarbageMan500]

Make a Joule Thief. I see what you did there.

[freakyqwerty]

I don't.

[xAxrules]

Could you make a proper schematic please?

[bambangpe]

inspire me...

[metroid62]

Ah yes, I'm about to get the parts for this, I'm excited because this is going to be my first minor project that involves batteries and LED's.

[macman808]

same here i found that i can get all the parts for $4.86 from my local jaycar

[Jimmy Proton]

thats a lot more than i would pay for some thing like this

[zack247]

will this work with normal thin wire? or what about the wires originally on the toroid?

[1up]

Yeah, either should work.

[kondzio29]

My LED was shone all night on one AAA battery

[colin55]

For those who have built the circuit and only achieved low brightness from the LED, here's an improvement that will not only increase the brightness but consume 50% less current. Connect the 1k resistor between the feedback winding and positive of the supply. This means the end of the feedback winding that was originally connected to the 1k resistor will now be connected to the base of the transistor and the feedback winding will now be connected between base and 1k. Connect one lead of a 22n capacitor to the point where the 1k meets the feedback winding and the other lead to the negative rail. The current will drop to less than 50% and the brightness will increase. This makes the circuit much more efficient by forcing the energy produced by the feedback winding into the base of the transistor. This turns the transistor on more and faster than before as it acts as a “barrier” or “stopper” to the energy produced by the feedback winding flowing into the 1k resistor. The energy now gets sent almost entirely into the base of the transistor. Try this and see the huge improvement. Colin Mitchell TALKING ELECTRONICS.com [e-mail]

[acmefixer]

The circuit Colin gives has an output that is highly dependent on the value of the capacitor. I've built this circuit and found that the LED was very dim. When I reduced the value of the capacitor to around 680 pF, the LED got much brighter. If your circuit has poor performance, change the capacitor to a smaller value, try 1000 pF or 1 nF. Ceramic disk caps are usually marked 102 for a 1, a zero, and two more zeroes, which equals 1 nF or 1000 pF.

[colin55]

You will notice a mistake in the circuit above. It will not work on a voltage below 0.7v - the circuit says 0.3v - 1.5v

[ekmath]

Hi, I just made the Joule thief the way you suggested. And it's really dim, just like when I made it like in the instructable. But when I short out the 1k resistor, it lights up like crazy! And the voltage drops from aroutn 0.8 to 0.5. Is this bad for any of the components in the circuit? Nothing gets hot, haven't had it on for ages like this though.

Eirik.

[Mercurion925]

Thanks for that post. I am an amateur electrician with a special interst in circuits like blocking oscillators and joule thiefs.... maybe this post can explain why some of the circuits I've tried don't work so well

[acmefixer]

I assembled one of your circuits, but was unable to duplicate your results. See my blog here on it. Please leave a comment.

[acmefixer]

I'll have to assemble one of your JTs and see how it works.
I think this works similar to my Supercharged joule Thief. The scary part is I'm getting efficiencies of over 90 percent!! See my blog here.
http://watsonseblog.blogspot.com/2009/01/joule-thief-high-efficiency-isthe-topic.html

Also, if people would give up using the 2N3904, which can't handle enough current, and move on to the much better 2N4401 or BC337, they would be pleased by the much brighter LED output.

Thanks.

[tonythemediaguy]

Hi, I tried your mod to this. It seems to work with and without the capacitor. How can I tell if I did this right?

[joinaqd]

wowowowowowowowwowowow! awesome dude!! i made it and make it light up LED brighter!

[colin55]

Almost any NPN transistor will work and any transformer made from a piece of ferrite material will work (antenna rod from a radio, balun from an antenna feeder/splitter or inductor from a power supply). Just wind 30 turns on the "core" for the secondary and 20 turns for the feedback winding. Almost any fine wire (enamelled wire) will work. Choose the thickest wire that will fit onto the core. Use the improved Joule Thief Circuit. The addition of the 22n is the secret to success.

[imakethings]

hey Colin can it improve the brightness of a green led?

[colin55]

None of the pulsing circuits will improve the brightness of any LED. If a LED is designed to produce maximum brightness with a steady DC current of say 25mA, pulsing the LED (even with a high current for a short period of time) will not produce more brightness. But it may produce nearly the same brightness with a lot less (average) current.

[egpacheco]

Thanks Colin. I did it the way you described and it works just great. I would like to ask about the amount of turns that would be the optimum (more cable more resistance, more turns more reluctance isn't it), and of course the diameter. Thanks again for this contribution and all the other ones!!!

[colin55]

20 to 30 turns is about the best for each winding. You can experiment. It also depends on the type of core material. The problem is: you only have 1.5v supply and if you add too many turns, you will not get the "turns-per-volt" (really the volts-per-turn) you need to get an output. In addition, the inductance of the primary will be so high that very little current flows when the transistor is conducting and thus the output will be very small.

[acmefixer]

@Colin
The higher the inductance, the greater the energy stored according to the formula found here (scroll down to stored energy).
http://en.wikipedia.org/wiki/Inductor
The greater the energy, the more power is transferred to the LED.
The greater the inductance, the slower the Joule Thief will run. I've built them with coils with high inductance and they are running at frequencies that I can hear, about 700 to 1100 Hz.

The Joule Thief coil does not work as a transformer; the output is taken from the same winding that is connected to the input. The feedback winding does not do anything to change the voltage, it just provides a signal to keep the JT oscillating.

The Joule Thief is very tolerant of the type and inductance of the coil. But as you said, 20 to 30 turns is a good point to get it running. Some toroids are low permeability, not much more than if the core material was made of air! In this case, it would be better to use more turns to keep the JT from running a too high a frequency.

[egpacheco]

Hi Colin, I want to ask a question related to this. Can you step up current from 1.5 v to light a LED, but without using a coil, I have seen some torches that use a single 1.5 v battery and have a couple of resistor a capacitor and a transistor AND NO COIL, but,.. I can not work out the circuit. Can you help with this. Thanks a lot for your help. Regards.

[colin55]

Here is a capacitor multiplier circuit to light a LED from 1.5v:

[ReCreate]

Does it have a chip? And measure the 1.5V cells with a multimeter to make sure they are 1.5 Take a picture of the PBC and post it too

[egpacheco]

OK. I asked that question because I read this instructable (http://www.instructables.com/id/S8NHACXFENTSOKM/) and there is talks about 50-60 turns (lemon powered led) I want to built it with my son (he is 9 years old. We already built your design on a protoboard and he is amazed to be using batteries he was ready to throw away), but using your circuit since the coil setup and 22n cap are more efficient. Thanks a lot.

[colin55]

If you like to work with clever circuits like this, see my improvements to
Shake it like a Tic Tac. My circuit is part-way down the page:

http://www.instructables.com/id/Shake-it-like-a-Tic-Tac!/

[sumaru]

hmm, nice. colin55 can you give me diagram of a joule thief, im trying to make a project, the project is peltier cellphone charger. Usually cp charger output is 5.4 volts and about 200 ma current. can you help me out? it seems your an expert.

[colin55]

Are you heating up the peltier module?

[Dreistein]

could you power a motor with this?

[w0rm5]

Is it possible to drain 3v coin cells with this? Or the led itself can drain it all from 3v? I´m new to electronics and was wondering how could I do it.

[1up]

You can hook a 3v battery up to this, and it will regulate the voltage pretty well. It will drain the battery from 3v probably all the way down to 1v.

[tinstructable]

Mine definitely worked, but whenever I tried to measure the voltage, it just reads 1.2v... the voltage of the battery. What is wrong?

[1up]

You mean it lit the LED, but your multimeter said 1.2v when you measured it? I will guess it's because it's putting out around 3v, but it's half on and half off, so your meter reads about 1.2v.

[tinstructable]

Nice Instructable. I got all my parts for free from samples. 3 Transistors and 3 different ferrite 1/2" beads. Check out this instructable if you don't know what I'm talking about. "http://www.instructables.com/id/Free_Electronic_Samples/"

[fundash]

Since I got my laptop, I havn't used my desktop because my laptop is so much better, how can I get a toroid out of the computer?

[tbt10f]

anything you take the toroid out of will be destroyed. if you want to destroy your old computer, the toroids (not all of them have some) will usually be located near the CPU and are usually dark grey in color with wire wrapped around them. Many power supplies also have toroids inside, but be careful to let it sit for a few hours before opening after you have disconnected the power because they can hold a charge and you could be electrocuted.

[anupamvipul]

it would be great if u add theory of coil used and diagram with colour

[ARJOON]

is your toroid well wind because copper wire should go there i think.

[fundash]

Nevermind my last post, but I found some wire from a usb and it worked... The only problem is it worked only when I first tried it, now the LED blink quickly and then the transistor starts to heat up :( heres a pic:

http://img59.imageshack.us/img59/9007/picture335f.jpg

[fundash]

Help, I could only wrap 5 turns around my toroid I got from an old graphics card! It just won't budge, will 5 turns work still???

[krapphace]

thanks for sharing with us

[seamaas]

can you use either a C1740S R4,A993S R4,or a A950Y 2A. And can you use a brown,black,red, silver, silver resistor or brown,black,red,gold

[dhoi]

not working

[Blofish]

Outstanding detail!

[arvee1991]

of course i found that out accidentally after i soldered it.........:)

[arvee1991]

the circuit works if we reverse the connections of emitter and collector respectively

[gizander]

Dudes, we should be so lucky where i live to even have a place to get any electrical/electronic (almost) part/component that we need (even it is from "Rat Shark" haha! I cant find inductors for a radius of 150 miles...mostly just salvage or wind my own air cores if i need it "fine tuned"...BTW, are the guys at RS as ignorant as the salespeople at my local electronics shops? I was having trouble with a pinout for a Q and the owner of the shop couldn't tell me E from C (internet was out...have a nice pinout sheet now...it's here if you're interested: http://hamradio.lakki.iki.fi/new/Datasheets/transistor_pinouts/) Anyhow, the Real reason i'm leaving a comment is...just in case any of you have an '88 Compaq PS, theres a nice 1 inch or so (OD) toroid nicely prewound in there in blue and brown--9 turns exactly. It's thick gauge wire (16, im thinkin') so it should be strong. There are also 2 beefy lookin' toroids in there (1 1/2" odia and 3/4 inch wide!!!) and it really isn't as hard as it looks to take the enamel dunked copper off them. ... lotta good caps there, Rs and power Q's too (With the required heatsinks =)... I suppose if you dont have a junk '88 Compaq, something from the era of R.E.M New Order will do as well...lol. Cheers all! And thanks for the great 'iables 1up man!

[rohanpsp]

 hey i made a joule thief it worked fine.but how to add capacitor to it plz help me.

[dasimpson1981]

could you build this with a bc337-25 pls and let me know how long it lasts and then compare it with a 2n3904 and let me know i would do it but my founds are so limited i can not get hold of the 2n3904 for a while

[dasimpson1981]

i was just reading and found a small bit of information about schottky diode. it said it can be used as a bridge diode to speed up the Oscillation of the circiut. by putting the anode of the diode to the base of the transister and the cathode to the collerctor.
do you think this would add grate improvement or lead to problems ?

[dasimpson1981]

ok this may sound realy daft but what is we build a low power loss bridge rectifer and put that befor the led

[1up]

It would do nothing, because this joule thief does not put out AC voltage but rather a pulsating DC. It is turning the LED on and off very quickly, so adding a rectifier wouldn't have any positive effect.

[dasimpson1981]

i been trying this with a 13001 transister but can not get it to work what makes a 13002 work but not a 13001 i got all my parts from a dead cfl bulb

[1up]

A 13001 is likely a PNP transistor while the 13002 is NPN. You need an NPN transistor for this project, not a PNP. Just because they're 1 number off does not make them similar. ;) That's one thing you need to learn.

[grampafish]

for high brightness use the same circuit as in the 'ible but replace the transistor with a BC547 this transistors pins are in the opposite order than the 3904
i use this transistor and it works very well

[grampafish]

or use my circuit

[grampafish]

i made a flashing one using a center tapped ac transformer

[chingon]

what is a toroid bead

[1up]

Try this site, it's got tons of information. Link

[zack247]

would an already made toroid work? or does it need to be like yours to work right?

[1up]

You can use one as long as it's wound the same way.

[beehard44]

it is a diagram, not a schematic, okay?

[1up]

:P
Alright, sure, I suppose it is.

[Kryptonite]

Now all I need is the transistors, then I'm good. In the mean time...

[schaude]

i tried making one with a colour-changing two-legged led. what came up was the led just lighting red all the time. thinking about it brought the result: the output voltage is not dc, it's kinda ac. so putting some diodes (ac-dc bridge) and a capacitor between circuit and led brought a good result. later i put all in a natural bath sponge (nearly banana-shaped) and gave it as a birthday present to a friend. two weeks later his bathroom still is glowing in fantastic colours! thanks for adding these nice and helpful instructable and comments.

[smidyt]

why does the led have to be white or blue?

[lasermaster3531]

cambigfoot means any 3-4 volt LED. 1.5 volt LEDs are very rare.

[cambigfoot]

no its any 1.5 vlt led

[1up]

It doesn't, it can actually be any color.

[cynical_chemical]

so... what kind of household objects can i get a toroid bead from?

[akinich]

a cfl bulb

[Earths_hope]

DVD players! they hold the circutboards together.

[Questioneverything13]

Compact fluoro lights have them.

[1up]

"You can find toroids in a few places. Old computer motherboards, XBOX and X360 motherboards have them (don't take them unless it's dead!). You can find toroids in computer power supplies, or you could buy them at your nearest RadioShack."

[pdumont]

You can also find in the CFL the necessary wire to wind the toroid. There is a small black coil right off the AC line. Unwind the coil and there is more than enough wire to make the coil. I wound my coil full and it is working like a charm. Double the wire,twist both ends, when full be sure to wring out the wires and proceed with instructions. Good luck

[acmefixer]

Radio Scrap wants eight bucks for a small bag of a few toroids, and you have to unwind the heavy wire, but that's not hard. Go to www.Mouser.com and get some Fair-Rite 2643002402 medium permeability or 2674002402 high permeability cores. I forget, but I think a hundred of them is either $6 or $11 per bag.

[M4industries]

Haha! Radio Scrap!

[Father Christmas]

I find Radio Crap easier to say.

[1up]

Or Rat Shack. :P

[grampafish]

crap shack

[realtico]

Radio Shark! it bites your wallet!

[Possum Living]

Shady ol' Racket.

[cynical_chemical]

oh.. i found one in a compact flourescent bulb!

[KnexFreek]

 real nice :) me likey :)

[_Scratch_]

in order on the transistor isn't it Emitter, collector , base.........not emitter, base, collector? just wondering, im just starting to learnabout this stuff.

[1up]

It really depends on the transistor it is. For this one, look in the first picture. From top to bottom it's collector, base, emitter. Just follow the pictures for the soldering and it'll be easy.

[anfegori91]

Why my joule thief is turning on and off the led ? (I know, that is what actually does).. but it was on for 2 days approx, and now is flashing ~30 seconds off, ~10 seconds on; first it was flashing ~30 seconds off, 20 seconds on.

[1up]

I don't know... Maybe your transistor is bad?

[raykholo]

 that kinda makes sense.   Since both legs of the LED are hooked up to the transistor it makes sense that the voltage is being switched back and forth
pretty cool though cuz if u messed up the wiring said result deserves an instructable of its own   "joule thief flasher" 
anfegori91  look carefully at what u did there....

[Wargasm]

I just got finished experimenting with a higher voltage version of a 'joule thief'. It lights series neon pilot bulbs brightly. And, if rectified, it can be used for charging high voltage capacitors. It's only around 600-700 milliwatts, so don't think you can run your color tv off of it. I used 10-0-10 turns on the primary side with 22awg wire and 368 turns of 30awg for the secondary on a 0.50 inch ferrite toroid. And I used a 2N4401 for active device. With a "dead" battery (about 0.90 - 1.00 volt) I measured around 350 volts output. With a fresh AA battery, the output reached beyond 700 volts! If you have enough wire, and the patience for fooling around with the aggravation of toroid winding, it's possible to get 1,000 volts or more. It's not magic.... Camera flash circuits use this step up transformer action to charge the photo capacitor, but it really is neat to make one for yourself. A word of caution to anyone interested in trying this: although the output current is weak (IF you use low power parts and operating voltage), the high voltage does sting a bit! don't go sticking to people unexpectedly, you could get punched in the face!

[1up]

Could you take a picture of it? How many turns would you use to get, say, 60v?

[Wargasm]

well.... for some reason, the post with the pics in it was removed... oh well.... watch it end up on another page or something.... Here it goes....again. I took the pics with my phone, so they are a little blurry. Even though I have a 2 AA holder, I wanted to operate it from a single AA battery. The output voltage with a slightly used AA was a little over 700 volts AC at a tiny weenie amperage. Connecting just one neon drug the output voltage down to around 368 volts AC (I can't really remember from yesterday's post, but it's close I guess). So it would light at least one more bulb. I used 2.2k ohms for the feedback to base resistor. When I lowered it to 180 ohms the output reach 850 volts AC, but the transistor got quite warm. It will supply around 600-700 milliwatts. You can use a power transistor such as TIP31, TIP41, TIP3055 or similiar to get more power. You would also need to increase the diameter of the windings on the coil. For every 10 watts of power, the circuit will draw around 1 amp. So you need a high current power supply. Like 12v said, not all torroids work. Such as, Iron Core types.... As long as it is ferrite, it WILL work. It doesn't even have to be a toroid-- I used the old loopstick antenna out of an AM radio to build one. For the one in the pics, I used one of those big ferrite cores that they slip onto computer monitor connectors. It measures around 1/2" by 1/4". For 60 volts AC, I would start with 60-100 windings of #42 to #30 awg wire on the ferrite toroid core. This will be your secondary. Then, using a little bigger wire around #24 awg, add your normal windings (the ones in your instructable pics) in the SAME direction as the secondary. This will be your primary. I used 20 turns for my primary. The number of primary turns determine the amount of output voltage as well as current. The more current you have, the less voltage you'll have. Start with 560 ohms to 1k ohm for the feedback resistor. The lower the value, the more output you'll have, but at a greater battery drain. Adjust the value for a good compromise between battery drain and voltage output. If it doesn't work, reverse your primary windings. It is quite simple, but trying to describe it in words probably makes it sound complicated. Hope this helps.

[jam BD]

Too complicated... LEDs...

[paleologos_the_greek]

BTW nice multimeter pal! i like this backlight

[weeny01]

hello from down under ,could you give me a diagram of your joule thief, the one you measured over 700AC on multimeter, please post it up, thamks

[Wargasm]

well.... wouldn't you know it..... the instructables 'Guides' thingy has cut off half of my post --------------------------------------->>>

Sorry... If you still want to read it, just copy it and paste it on Microsoft Wordpad or something to read it. This has got to be one of the worst commenting experiences ever!

[12V]

what neon glow lamps(otherwise known as pilot lamps) did you use? my ones (maplin rx70) only need 90v) 90v is almost standard.

[Wargasm]

(removed by author or community request)

[Wargasm]

And... yeah, I tried it with two AA batteries, but I couldn't measure the voltage because it made my volt meter go haywire when I connected it..... not good.

[12V]

this is because it exceeded your voltmeters maximum voltage measure.

[paleologos_the_greek]

and here is a full stress for the bc337... R1= 300ohm c1=1μF / 50v elca , and 8 bright white leds :) however the bc337 keeps pleasantly warm after 1hour of continuous operation...

[paleologos_the_greek]

here it is

[jam BD]

Pretty Lights...
Love LEDs..=D

[1up]

Nice! Looks great. :) I'm glad so many people are using this circuit; it really is useful!

[cantsolder]

Would a joule thief make magnetic induction circuits more efficient? For example would it allow for more current with fewer coil winds or fewer passes of the magnet? Please note I am just dipping my toe into electronics all because of a broken Reelight!

[gizander]

could a joule thief power a 4.5 volt digital alarm clock or would it mess up the clock's "timing"? If it can though, what would I need to make a 4.5 volt power supply (joule thief) and how would I assemble it? Thanks!

[acmefixer]

The Joule Thief draws a lot of current, so if you left it on 24/7, you would have to put in a fresh battery every few days. It would be better to tape three cells together and connect them in series, then they should last a long time.

[1up]

It might, I think you could change the resistor to make the voltage higher. I'm really not sure if it would work or not. You'd have to try it for yourself.

[nick4545]

Great Instructable and easy to follow, I completed my joule thief on the first try following these instructions and instructions from the joule thief on the energy seed lamp Instructable. Also used this to complete a project and report for school! Thanks for all the info and keep up the good work!

[dman446]

To m.halsey: I also put one together on a piece of perfboard for a more professional look, and was also disappointed when it did not work. BUT I found my problem that may also be whats wrong with yours as well. If you notice very closely on the pictures you have to make sure the (+) in side of the coil wires need to have one end in apposing direction connected together. AKA if you have a orange and green wire, connect the start of coil orange end and the end of coil green end together. Hope this helps

[the_lark]

You can also get 'em from RC li-po chargers. Some even have two toroids inside , a big one & a smaller one. Perhaps you'll find them in wall adapters as well.

[tonythemediaguy]

How can we do multiple LED's with this? Even if they lasted much less time, it would still be a lot of time. thanks!

[1up]

Simply put the LEDs in parallel. Use a 4011 transistor, they can handle more amps.

[tonythemediaguy]

Thanks! I picked up some 4011 and some BC337. I also did Colin's booster. I now have 6 LED's, maybe it could do more? If I wanted to add red or orange with their lower voltage, how could I accomplish this? Wire them parallel but with an added resistor? Thanks Again! Tony

[acmefixer]

I think he meant 2N4401, not 4011. A better one is the BC337-25, which can light up a single white or blue LED to full brightness ot two or three LEDs. If you want more you can parallel another BC337 across the existing one and add another 1k base resistor. Better yet is to buy a NTE11 (expensive) or KSD5041 from Fairchild Semi or Mouser.com. For the price of five NTE11, you can buy a hundred KSD5041.

[_Scratch_]

could u hook this up to a rechargeable battery? so while it sucks the energy out it charges the battery then after u charge from a few "dead" batteries u have a fully charged energy source... Like a plug in recharger but it uses dead batteries as a power source instead of a wall outlet.

[1up]

Sure can, check out this Instructable:
http://www.instructables.com/id/Joule_Thief_Charger/

[SpecieS~]

I've made a little project with help of your instructable. Would you mind if I publish it as a slide show? I'll add a link to this instructable and mention you as the author of the circuit. ;)

[1up]

Not at all! I'd love to see it. :)

[SpecieS~]

got a problem I have to solve before I can publish it... and I saw you have the solution in this instructable. How do you use single words as links? I've tried it with html but it doesn't work. :( The link function of instructables just shows the url as link and that's what I don't want

[SpecieS~]

I found the solution for the problem :D (there really are instructables for everything XD). Now the slideshow is ready

[12V]

I have made an instructable about the hv joulethief
http://www.instructables.com/id/high-voltage-joule-thief/

[12V]

i made a 90v one by using a third coil! the joule thief thingy is only connected to 2.4v! i wound 90 turns of wire out of the primary an old transformer(high volt side) and then used the lv side wire (thicker) to wind the normal joule thief windings and ended up with a joule thief that can light a neon glow lamp(wire ended type) off 2.4v.

[1up]

Dang, that's awesome! Any idea how many amps it puts out? Could you give more details? You could make a 120v one and run a lamp from 3v! :D

[12V]

Hi. this joule thief only puts out about 1/2w i used it to light up my neon glow lamp (wire ended type about 1/2w) but you could try .. (for a slightly more powerful) use 0.15-0.2 mm magnet wire to wind 1v per turn (with some load) (you want about 120-125 turns wind the normal joule thief windings (i used 5turns tap 5turns0.4mm wire) to make more powerful try a tip122 and use one wire twice as fat as the other(you used orange and green) the fat one is connected to the collector NOT the base! use lower value resistor. this will also increase voltage .

[1up]

Would it be possible to make an Instructable? With really nice pictures? I'm interested in doing this but can't quite understand what you're saying.

[12V]

hopefully i will make an instructable but please allow about a week of two! it is just a one of your joulethiefs with a third coil of about 100 windings wind 100 coils of thin wire on the toroid and the wind the joulethief (please only use 5 windings not the normal 7-11) please note that this does not work on all ferrites! i used either a small white one(7x3 with 2.5mm hole) or a blue one of 13x7 with 8/9mm hole i tried a black one of this size it did not work!

[Wargasm]

Did you wind your xfrmr on a torroid?

[12V]

sorry please can you tell me what you mean by xfrmr if you mean the 90/180v joulethief like the comment above then yes?

[Wargasm]

i was just too lazy to type transformer....sorry.

[mikedoth]

Dumb question, I picked up 2N3906 pack of transistors (expecting to make several of these), will these work, I assume so but want to check before opening the package.

[Wargasm]

Yes, they can be made to work. The only difference is that the collector will be connect to ground because PNP type transistors require a negative voltage in order to conduct rather than NPN, which require a positive voltage.

[mikedoth]

Long shot here, but do you have a diagram of how that would work?

[1up]

No, those are PNP. You need an NPN transistor. Get a 2N3904 or 2N4401.

[mikedoth]

What applications can I use these for?

[dombeef]

This
http://forum.allaboutcircuits.com/showthread.php?t=14720
Or this
http://www.elecfree.com/electronic/solar-regulator-by-2n3906/

[dombeef]

Or just google it :" projects with 2N3906"

[Kante Tech]

do you need a toroid n order for it to work or can u subs something else

[unseen wombat]

1Up, I don't know what Radio Shack you have around you, but I can't find any toroids there. People look at me like I'm stupid (well, more like they're stupid) when I ask about them. Radio shack is such a joke any more. They ought to call it cell phone shack, or RC toys shack.

[Wargasm]

REALLY! They take a hobbyist's paradise an turn it into a freakin' consumer electronics nightmare!

[1up]

Isn't there an "Inductors" drawer? Did you check drawers that might have them? They have them on the website.

[12V]

i have just finished my 180v joule thief! the picture shows two neons in series.. a neon has a strike voltage of 90v so two means the joule thief must be at least 180v! the supply is 2.4v. i only did 110 windings!

[Phattie Mcgee]

Hi 1up! :) I've tried to build a few of these, my results so far have been less than optimal. I'm thinking I should just buy some better parts to make one if you (or others) could be so kind as to let us know what parts would work. I.E. a 100uH Toroid inductor (371856 jameco), w/ NTE11 transistor, etc I'm wanting to build about 5 of these when my sister brings her kids and my daughter up to visit for the summer on July 20th, so while I still have time, I know im still going to need some except advice :D

[1up]

Hey McGee! I'm not sure if you can use pre-made inductors for these. First off, is the toroid you have magnetic? Make sure you get 7-11 turns on it, too. The wire should be really thin, like 28-30 gauge or magnet wire. Check all your connections, and make sure you have the right parts. Many people report this not working, but many report it does. I need to find out what the problems are and try to fix them. :/

[Phattie Mcgee]

I found a circuit on http://www.quantsuff.com/index.htm (very bottom of page) that allows a circuit to be run with a off the shelf parts!

so I ordered all the parts and got 220uH toroids w/ 2200pf capacitors, lets hope it works!

[magicdust]

A great source of components for this is electronic circuit board inside of a CFL (compact florescent light). Just because the light doesn't work doesn't mean there is nothing usable inside. (Sorry about all the negatives...there IS useful stuff in them when they don't work.) Inside you will find power capacitors (the two largest electrolytic ones are usually fried and the main reason the light doesn't work anymore), 1N4004 diodes, 13002 NPN power transistors, various resistors, a multi-winding transformer AND a pre-wound toroid inductor. The 13002 transistors (400 volt, 1A) are more powerful than either the 2N3904 or 2N4401 (about 60 volts and 0.2A ). ALL for FREE if you just repurpose stuff.

[Phattie Mcgee]

I guess the one on the left (green, 6 legs) is the toroid and the one on the left (yellow, 4 pins) is the transformer? The cfl I got these from also has 13003 transistors (2 of them) 2 caps at 200v 15uF a bunch of ceramic looking things labeled 400v 47nK, 1000v 1 no j ?, 1kv CJB and of course diodes and transistors

[12V]

i have taken loads of these apart and found lb124d 13001 13003 13002 transistors i have just tested the lb124d and it works on the joule thief!

[1up]

Thanks for the info. I'll add it to the Instructable.

[12V]

i made one using a cfl transistor(lb124d from 11w phillips gene and also used the ferrite!

[dombeef]

How about the resister at black brown orange silver?

[1up]

Nope.

[dombeef]

ok

[dombeef]

Will telephone wire work

[1up]

Probably, depending on how thin it is.

[Wareagle]

will a flat toroid work? by that i mean one that is not doughnut shaped

[1up]

It should, try it and tell me.

[dombeef]

Can you show a picture

[Wareagle]

at least i think it is a toroid... i added a penny for size comparison. by the way it was in a radio and was wrapped with wire.

[Wareagle]

uhhhh i am having a problem uploading a picture, but it looks like an elongated brick and it is a ferrite core.

[dombeef]

Where is the picture?

[dombeef]

Will a 10 ohms resister work?

[1up]

No, it won't.

[Wareagle]

no i dont think so. just go out and buy a 5 pack of resistors at radioshack. it only costs $1.

[drusilla]

Awesome, this worked out perfectly. Thanks for the instructable.

[imakethings]

Which transistor will i need to handle 25-50 leds with this circuit?

[dombeef]

You will need a bigger toroid and 2N4401

[ReCreate]

I now got the Toroid,with wire,and the 1K resistor,All i need is an LED and the transistor,Will a red or green LED work?

[1up]

Both will.

[ReCreate]

Will any LED work? I got: @ The LED(1Red 1Green 1 Yellow) @ The toroid @ The Resistor And i finally understand the schematic!

[dombeef]

Yeah

[dombeef]

Would a red,red,brown one work?

[omega9o]

ok does anyone know what transistor to use on a larger scale of this thing

[1up]

Try a 2N4401 transistor.

[dombeef]

How about the Resisters?What K. would it be?

[ookid]

OK, I hooked every thing up just like in the pictures and it doesn't work. I'm using cable stripped from CAT5. Any thoughts? The transistor is new and I also tried the circuit with a 2n3903 which is very close to the 3904. Please help, I've tried everything I can think of.

[1up]

A 2n3903 won't work. It is the PNP equivalent of a 3904. You need to get a different transistor.

[ookid]

Oh I figured "only one number off..." I also tried it with the 3904 and diddent work either.

[1up]

Is the cable actually stripped? It must be insulated. If it still doesn't work, try magnet wire. How many turns did you get on the toroid? Where did you get the toroid?

[ookid]

Yes the cable is insulated. I have 11 turns on wire on it. I got the toroid from an Electronic surplus store. The toroid is painted but I don't think thats a very big deal.

[1up]

I don't know, then. :/ The only thing I can say is to check your connections, make sure you didn't over heat the transistor, and maybe try magnet wire to wind the toroid.

[cclementi6]

question: why does there have to be a transistor and resistor there? why can't you directly hook up the wire from the toroid to the LED? have pity on me if its a stupid question, im new to circuiting, lol.

[1up]

In this case, the toroid's job is kind of like a capacitor. It holds a charge until it's around 3v (enough to light the LED). Then the charge overcomes the resistor, triggering the transistor to release the charge into the LED. This happens thousands of times a second so it looks like it's on all the time.

[egbertfitzwilly]

Is there an optimum relationship between the coil windings on the toroid and the input voltage range? Can this be 'tuned' to provide the minimum possible drain for a target output voltage?

[egbertfitzwilly]

I shared this instructable with a friend of mine who naively thought toroid coil was some sort of technical name (or could be replaced by) an iron core. He made a very nice electromagnet....

I found these at Radio Shack in a 5 pack for $7.99.
http://www.radioshack.com/product/index.jsp?productId=3097455&tab=features

[strmrnnr]

I have a question for you. If I use one of these with a new battery - how long does it extend the life of the battery?

[1up]

Usually about twice as much.

[firdaus93]

Could you tell me what's the toroid equivalent to in Henry(H). I've been trying with the toroid and have no luck. A schematics also is good. Thx

[1up]

A schematic is in the last step. Not sure about that other question, though.

[firdaus93]

What I mean is what value should i buy for the inductor to work on 2 AA batteries.

[strmrnnr]

I do not think there is a value on them. I will save you some hassle. I when to the source to buy one and they never hear of them. Salesmen? Anyway, just use a metal nut (if you like drill the threading out. Stacked washers may work, but I think there is an issue with the seperate ring being brought together screws with the formation of a properly shaped magnetic field.

[Jodex]

I ordered two of those toroids and transistors and I'm gonne get them on monday. I'm gonna make two "LEDded" pocket light.

[ReCreate]

Do Power supplies have a toroid? I got something that looks allot like the one in the picture that had coil wrapped around it,and the center material,is it a toroid? It says"58BU 77310-A7" How can i tell if this is a toroid?

[blakdragon19]

toroid is a 3-dimensional shape, and the word is used to describe an electronic component that is a ferromagnetic core for amplifying and incucting electricity. if it is a donut shaped object that has wires wrapped around it and you can attract it with a magnet, it will work.

[ReCreate]

Ah great,Its just like what you said

[dombeef]

Yeah it is mostly

[ReCreate]

Yes its mostly a toroid? What do you mean?

[dombeef]

I mean It is probably a toroid

[ReCreate]

Oh,good Now,off to finding the transistor!

[dombeef]

Yeah I found one but it broke

[ReCreate]

"no need to fear,my idea is here..."\
Anyways,Try to superglue it together

[dombeef]

NO but it just doesnt work

[ReCreate]

The toroid or the transistor? I meant for the toroid,you can superglue it

[dombeef]

The transistor

[ReCreate]

DOH...Well the transistor,yeah,its hopeless,but the toroid,...well you get it. I meant the toroid all this time

[dombeef]

Well finally bought the resister

[ReCreate]

I only need the transistor,Go the toroid,Resistor,battery,Led,Only thing,transistor

[dombeef]

And I bought the wrong transister! UGGGG!!

[ReCreate]

Ouch... Look at this

[ReCreate]

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[ReCreate]

Ash,Its All Wrong Look at this,In the txt file

[dombeef]

How is it ouch?

[ReCreate]

Its Ouch Because its a pain that you bought the wrong one.

[dombeef]

But the wrong one is right because I got a super Toroid that needs the transister for it to work!

[ReCreate]

Ha Well then Lucky you! I still don't have the transistor, And Probably won't have it for a while too.

[dombeef]

Well then good luck!

[ReCreate]

THanks

[dombeef]

You welcome

[ReCreate]

You welcome? Umm, Ok

[dombeef]

Sorry "Your"welcome

[ReCreate]

Uhm...Ok (what do you say back to someone when they tell you you're welcome?)

[dombeef]

Um... YourWelcome?

[ReCreate]

Um, your welcome too.

[dombeef]

Your welcome...

[ReCreate]

So is this supposed to be an infinite chain of your welcomes?

[dombeef]

Well ... Yeah i guess

[ReCreate]

Ok then, Your Welcome too.

[dombeef]

OK Your Welcome too too

[ReCreate]

Your Welcome Too Also Too

[dombeef]

Your welcome too too too

[ReCreate]

Your Welcome Infinity too. Can't Beat that ;P

[dombeef]

Your Welcome Infinity + googolplex ! (even though it makes no sense)

[ReCreate]

Your Welcome Everything that you said Times it self infinity! Can't beat that!

[dombeef]

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[ReCreate]

How did you get it to work? Also,How do you think i made this?

[dombeef]

Using a picture to text aplication and You use the robot text { { {...

[ReCreate]

Oh yes Monospaced text, Also Know any (Good)Picture to text applications? The One i Have is not so good

[dombeef]

OK here is one http://www.glassgiant.com/ascii/

[ReCreate]

Haha nice

[dombeef]

Yeah

[ReCreate]

Yeah

[ReCreate]

Looking at it now

[ReCreate]

Oh,you tried? I heard that you could fix,em up by superglue,anyways,those suckers are like the 3rd most common thing everywhere,i got tons of those

[acmefixer]

If you use the 2N3904, you will get the LED to light, but to full brightness (the reason is that the 2N3904's maximum current is only a tenth of an amp, and you need 3 times that much). There are some other transistors that do a much better job. One is the 2N4401, another is the BC337. If you can get NTE replacement transistors from an electronics dealer, you can use the NTE11, which will power three white or blue LEDs to full brightness. Another way to get the LED to be fully bright is to put another transistor in parallel. Connect the second transistor's collector and emitter (the outside leads) to the first transistor (make sure they are the same leads!). Then connect the base (the center lead) to one side of another 1000 ohm resistor. Then connect the other lead of this resistor to the coil lead, where the first resistor is connected. If you use a 2N3904 as the second transistor, you might almost get the LED to light to full brightness. You can find out a lot more about this and other LED projects in my blog: watsonseblog.blogspot.com.

[blakdragon19]

so what kind of resistor would i use with an NTE11 transistor?

[Luxordo5]

so one 2N4401 will be enough to power one ultra-high brightness led at full brightness?

[acmefixer]

It's hard to say. The 2N4401 will handle up to a half amp. which is 5 times the maximum current for a 2N3904. Assume that the LED needs 20mA at 3.3V for full brightness, which requires 3.3V ( the LED's V drop) times .02A or 66 milliwatts or .066 watt. Assume that the Joule Thief circuit is 66% efficient (2/3 of the input power gets to the LED). So divide .066 by .66 and it gives .1W or 100 milliwatts input power, which is what's needed from the battery. The cell is at 1.5V. Divide .1W by 1.5V and it gives .067 amps., or 67 milliamps, which is the current that is needed from the battery. I put a 1 ohm resistor in series with the battery lead, and put my digital voltmeter across it and measured the current for different transistors. The meter will read 1 miliivolt for every milliamp when it's set on the 200 millivolt range. Using the 2N3904, I found that the battery current was well below this 67 milliamps. Using the 2N4401 the current was typically above the 67 milliamps, sometimes near 80 milliamps. Using the BC337 or BC338, I found the curent was around 100 milliamps, sometimes a bit over. But I was using a toroid with heavy #24 gauge wire. When you build one of these projects, some call for winding thin #30 gauge wire on the outside of the battery. It's difficult to say what the efficiency is for a coil that's made with thin wire and wound on a steel battery case. So having the transistor pull a hundred milliamps from the battery may not be putting 2/3 of that to the LED. And it doesn't hurt to run the LED at more than 20 milliamps, for a flashlight it shouldn't hurt to run it hotter at 30 milliamps. And the above doesn't take into account the situation when the battery starts to run down. Hopefully your joule thief will still put out useful light when the battery is at 1V or less. For me, every little bit helps, so using the 2N4401 or BC337 is a must, and the2N3904 is a no-no. Now I've been playing around with the 1W LEDs I bought from Mouser, and I need ten times as much current from the circuit and from the battery. It's getting even harder to get the circuit to draw a full amp from the battery! Remember that the circuit is drawing 1 amp (or 100 milliamps) average, but the transistor is turned on for only part of that time, and is drawing a lot more current, up to 5 times the average. This is why high current transistors are very important.. Best of success with your projects. watsonseblog.blogspot.com

[SpecieS~]

I made some joule thieves with two parallel 2N3904 transistors. Now I want to buy some BC337 transistors to make the joule thieves smaller, but I found 3 kinds of BC337 in the store. BC337-16, BC337-25 and BC337-40. Is there an important difference between them or is it regardless of which I take?

[acmefixer]

The numbers indicate low medium and high beta, AKA current gain versions. I get the BC337-25BU from Mouser for $4.40 a hundred. www.mouser.com and search for BC33725BU.

[SpecieS~]

Thanks for your fast answer. But there's one problem left. I'm from Germany and shipping that little letter would cost me 20€. I'll try it with the bc337-25 from reichelt.de .

[tonythemediaguy]

Thank You for your very helpful answers on here. What if I wanted to light up 5, 10, 25, whatever LEDs? Even if only for a short time? I'm disecting a solar garden light, replacing. I made a joule thief but maybe I could just change the transistor on the solar light itself. Maybe it has everything I need already. And it's only $2.50/each at costco.

[pyro man]

ouch,my brain!

[Luxordo5]

Wow, perfect explanation. Thanks a lot! Now I just have to find a toroid... Radioshack sells in packs of 10 for about $8 and I don't want to spend that much 0_0.

[blakdragon19]

pretty much any old electronic device will have a few of these. just take some stuff apart and find one!

[geeklord]

i hate radio shack >:( But my only other alternative is to buy stuff online, so then i have to buy them online for about 10cents + $8 shipping! And ebay isn't an option either, because a)im 13 and don't have a credit card, and b)id have to buy them in bulk

[fallenspirit123]

I so fell your pain!!! I'm thirteen and I have to setlle with "the store" (Radioshack) every time I get a project

[rickyd!]

same here!! ugh!

[fallenspirit123]

we need to form a rebellion and take them over >;(

[rickyd!]

viva la revolution!

[ReCreate]

So then No radioshack.

[ReCreate]

its feel not fell

[fallenspirit123]

oh...yeah lol

[pyro man]

face it jullian,u love radioshack!

[fallenspirit123]

nope, its full of overpriced electronics but its the only place that sells components locally'

[ReCreate]

sounds good to me

[fallenspirit123]

lol, um...ok! buy overpriced electronics!

[fallenspirit123]

Oh and by the way sorry about the pic that wasnt supposed to be there and also I wanna say that in radioshack they sometimes tell me that I am the only person to go to their electronic component section for like 2 weeks!

[acmefixer]

When I go there I find that the parts are all in the wrong bins, if they have them at all. I go there only because I don't want to wait a week or so to get the parts from Mouser or Digi-Key. Radio Scrap is ten times more expensive than online electronics stores. But sometimes in desperation I use their parts.

[fallenspirit123]

same here

[pyro man]

lol me too i asked once for a transistor and that dude was like"huh?"

[fallenspirit123]

The guy I saw solders too (he was talking to me about soldering) and he was like "Im not even gonna ask because you probably kno the store better than me and I work here!!!"

[acmefixer]

Find a radio amateur 'Ham' in your neighborhood and ask him for advice. Some hams have spare parts around, or else they may know or can get in contact with other hams who do. When I was young I had to be very resourceful to get the stuff that I needed to further my electronic ambitions. Nowadays it's easy to find a used computer or PC power supply with some ofthe parts that you can use for building a Joule Thief. People are throwing away used PCs all the time, it's just a matter of finding one at the right time. As someome else mentioned, there are some toroids inside of the CFL's (compact fluorescelt lights), and used ones are not hard to find. Oh, and by the way, I hate Radio Shaft , too. All the salesdroids are interested in is signing you up to a cell phone contract. I seldom go there, since I found some online sources such as Digi-Key and Mouser. For a few years I was enthusiastic about Ebay and I bought a lot of stuff, but I got burned out on it after getting shorted on parts and after a few sellers shipped equipment so poorly packed that it was damaged in shipment. Nowadays Ebay seems to be flooded with vendors that only want to sell, not auction. Ah, well..

[acmefixer]

http://www.allelectronics.com/make-a-store/category/785/Toroids/1.html

They're inexpensive, but I can't speak for these parts because I've never bought any. I get my toroids from used equipment and cables such as mouse and keyboard cables. You can also find toroids inside of old PC power supplies. Some may be larger, some small. Some may have potting compound on them, making it more difficult. I sometimes take a plastic covered toroid outside and heat it with a propane torch, or else attack it with a pliers and/or utility knife. Remember that toroids are basically glass, so they can break. And you should know that you can damage it or yourself with a sharp tool.

You can also use coils and chokes. I've used coils with a single winding by winding fine wire over the outside for the feedback winding.

You don't have to have a second winding. You can use a single winding if you add a second transistor. Here's another instructables, but I'm not sure why QS used a second transistor when it would be simpler to wind the second winding. http://www.instructables.com/id/A_high_power_LED_torch_using_a_single_AA_battery/?ALLSTEPS

Have fun. watsonseblog.blogspot.com

[Infinitevortex]

If you decide to open a computer power supply, please be aware that these devices contain large capacitors which can hold enough charge to kill you. Unplugging the supply does not discharge these capacitors. I'm pretty sure that some computer motherboards contain toroids. Take care and have fun!

[acmefixer]

It is true that the capacitors can have enough charge to kill you. However, ALL power supplies that I have worked with have a several hundred k resistor (470k is typical) across these capacitors specifically for this reason, and will discharge the capacitors within a short time after unplugging it. Therefore your statement "Unplugging the supply does not discharge these capacitors." is incorrect. But to be on the safe side, check the capacitors with a DMM set to the highest range. If there still is a lot of voltage, use a 47k or so resistor to discharge the capacitor, and replace the resistor that's across the cap if you're repairing the power supply.

[Infinitevortex]

I was unaware of the resistor you speak of. Thanks for the correction! Is it possible that old power supplies (>9 years) might lack this resistor? I think I may have obtained the info regarding the non-self-discharge of power supplies from a computer book of this vintage.

[Derin]

ferrite is iron,but still handle ferrite like glass because it is brittle and fragile

[Pirate88179]

Ferrite is iron oxide, not iron. Iron is a metal, iron oxide is a ceramic. 2 totally different properties. Bill

[acmefixer]

Actually ferrite is not only iron oxide. Generally ferrite is a combination of other metals. Iron oxide is not ceramic, it has the consistency of a powder, as anyone who has worked with iron core toroids will tell you. You have to wash your hands afterward to get all the black material off. And anyone who has looked at a recording tape, from a tape cassette or video cassette, will know that the iron oxide on the tape is not ceramic.

[Pirate88179]

Actually, you are close. Iron oxide that has been isopressed and fired is ceramic. So, the ferrites used in toroids are ceramic. I spent over 20 years as a ceramic design engineer so I know this is a fact. We delt mainly with AL203 (aluminum oxide) but machined many ferrites for wave guides for microwave towers. Ferrite toroids do not leave powder behind as you suggest. The powder does but, that has not been pressed and fired. Trust me on this. Feel free to check out my Youtube videos on my channel. (Pirate88179) I can light 400 leds from my earth battery using a joule thief circuit. I have also designed and machined parts that have flown on the space shuttle. (Yes, ceramic again) Look it up and you will see what I am saying is correct. Bill

[acmefixer]

If you reread my comment, you will see that I did not 'suggest' that ferrites leave powder behind. Powdered iron cores aren't the same as ferrite. I have some powdered iron cores and the plastic bag is dark on the inside from the powder that comes off. that doesn't happen with ferrites - they are hard like glass. In the spirit of instructabling, I don' feel I need to brag about my quaifications, i think it's important the reader know when someone says something that's incorrect. Furthermore, I don't believe the reader needs to take my word for the truth - 'trust me..' - I furnish a link to a reference. What I know 'for a fact' is not what I want the reader to know, I think it's his responsibility to weigh others' opinions and judge for himself what is generally accepted as true.

[Pirate88179]

"Generally ferrite is a combination of other metals." This is your quote. It is incorrect as I tried to point out. Ferrite is NOT a combination of "other" metals, ferrite is a ceramic and contains NO metals at all. This is what I was trying to get across. "Powdered iron cores are not the same as ferrite" I could not agree more. On my Joule Thief topic at Overunitydotcom, we have over 9,000 posts on folks doing great experiments with these cool little circuits. I do not use powdered iron cores at all in my JT circuits as they do not seem to work well for me in our advanced research. But, having said that, there are some in our research group that have used them successfully. As far as bragging is concerned, I do not consider it to be bragging if, one, it is true, and two, it is relevant to be established as a credible source of knowledge and information on a given subject....sort of like a resume. I am sorry if you took that to be bragging. If you check my Youtube videos as I suggested, you will see I have done a lot of work on the JT circuits but, there are many folks in our group that are way, way more advanced than I am with these circuits. I am always trying to catch up. If you need me to furnish links to show what I am saying is correct, let me know and I will do so. I was not sure of the rules on doing that here. I do enjoy this site and have learned a lot from it. If I ever find the time and the patience, I will make an Instructable on some advanced JT circuits. It takes a lot of effort to do a good Instructable and I respect the folks that have done them. If I have misunderstood something you were trying to say, I am sorry. I was only attempting to correct another poster's information. (Derin's) Bill

[acmefixer]

I quote the following from your reply:
"ferrite is a ceramic and contains NO metals at all."

I think you had better reasses what you just said. According to the following patents, most if not all of the elements in ferrites are metals.

http://www.freepatentsonline.com/6790379.html

http://www.freepatentsonline.com/3609084.html

http://www.patentstorm.us/patents/6652768/claims.html

You can find more of the same with Google. Feel free to quote references if you disagree.

[Pirate88179]

Fe2O3 is iron OXIDE and all of the other main ingredients are also oxides as well....exactly what I have been saying here....or trying to. Bill

[acmefixer]

Again I quote the following from your earlier reply: "ferrite is a ceramic and contains NO metals at all." That's not what I read in the patents in the links I gave. I think you had better reread them.

[Pirate88179]

Quoted directly from the first patent link YOU supplied: "The composition of the ferrite composition of the present embodiment is not particularly limited. Various compositions may be selected in accordance with the objective, but it is preferable that the composition contain as main ingredients Fe 2 O 3 and at least one oxide selected from the group of MgO, CuO, ZnO, MnO, NiO, and Li 2 O. A typical example of the ferrite composition of the present embodiment is an Mg—Cu—Zn ferrite composition. "

I rest my case. No need for me to read any of your other links. These hard ceramic ferrites are fired at temperatures way above any that metal can survive. I am not here to educate you. I have been saying all along that these are metal OXIDES not metal which, as stated in my first post you had a problem with, have DIFFERENT properties than metals.

If you want to learn how to make a really powerful JT circuit that is very very close to unity, check out my topic on Overunitydotcom. Otherwise, I have other things to do.

Bill

[acmefixer]

Again I quote the following from your earlier reply: "ferrite is a ceramic and contains NO metals at all." Iron, Copper, Zinc are all metals whether or not they're bound to an oxygen atom. You can skate around words all you want, but you said no metal at all, and that's not what I read. I, too have better things to do, than to argue with someone who doesn't know the difference.

[Pirate88179]

Metals and metal oxides ARE two totally different things with totally different properties. It is what I have been trying to tell you all along. I even quoted (copied and pasted directly) from the patent YOU posted the link for. If you don't know the difference between a metal and a metal oxide, I can not help you. Look it up. Any high school chemistry book will explain it to you. Bill

[acmefixer]

Now I get the "Any high school chemistry book will explain it to you." excuse. Any high school chemistry book will explain how to reduce oxide to an element. Just because it's an oxide doesn't mean it's *NOT* a metal!

DUH!

An open letter to all other readers: I invite you to agree or disagree with what he said. I cannot reason with him; his eyes are open but HE CANNOT SEE.

[buteman]

Well if Pirate88179 had said a ferrite contains no ELEMENTAL metals there could have been no argument.
So acmefixer you are both, to some extent, right and you are both, to some extent, wrong.
To say a ferrite contains metal ( which is existing as a compound ) is true just as to say water contains oxygen.
Equally to say it contains elemental metal is wrong.

As the metals are in compounds they do have completely different properties just the same as hydrogen ( an element ) and oxygen ( another element ) have completely different properties to their very common compound H2O - water.
So I guess it is down to using the correct terminology.
Hope that helps to settle this argument.

[1up]

That's a good idea. Thanks for the insight. :)

[merseyless]

can i just say you can grab beads from dead compact fluresent lights.

[1up]

Yes, you can find toroids in CFLs.

[merseyless]

unfortunately for me, CFLs take aaaages to die so i'm stuck here waiting for one to pop.

[1up]

:P You'd be better off taking apart a good one, unless you would rather wait the 6-7 months for it to die!

[acmefixer]

New CFLs are under a dollar on sale here in So. Calif, where So Cal. Edison includes a rebate that lowers the price. I saw a table full of boxes of three for $3.99 at the store a week ago.

You have to remove the core and unwind the three windings, but that's easy 'cuz each winding is only three turns. There are other parts in there that can be used, too.

If you're going to do some serious experimenting with Joule Thiefs, buy some cores from Mouser the Fair-Rite 2673002402 (high permeability) or 2643002402 (medium permeability) make good JT toroids, and they cost something like $11 for a bag of 100.

[ReCreate]

It takes them a good 10 years to die...Just Somehow...Get lightning to strike it so it does bad and you have an excuse to take it

[ReCreate]

its too bad i threw out 2 bat cfls i've could have used them

[merseyless]

we have one that has been going for 5+ years! unfortunately we have invincible lights :( also i coulden't be bothered with spending money on a project.

[acmefixer]

Well, no no investment, no return, I'd say. Sort of like the old data processing adage: GIGO. When I was a young neophyte, I didn't have the money to buy what I often needed. But at that time, we had Heathkits, and I would save money and buy a kit, and then assemble it,. I spent a lotta time sweating over a hot soldering iron. But it was fun and educational, too.

[dombeef]

How many coils does it have to be?

[dombeef]

How many?

[1up]

Just wind it as many times will fit. If it doesn't work, try about 11, with thin wire.

[dombeef]

Oh ok

[ReCreate]

oh,I meant 2 by you use 2 Wires,not 2 turns,yes about 10 times

[ReCreate]

2

[ReCreate]

oh,I meant 2 by you use 2 Wires,not 2 turns,yes about 10 times

[ReCreate]

What would happen if i run electricity through the coil? through the 2 wires? What would be measured at the other end? if the input is 12v?

[1up]

I don't know. Try it and see. :)

[ReCreate]

Ill try

[ReCreate]

Thats weird,i tried it in DC it gets 1.2 volts,what the input is,but in AC,its 2.2V

[ReCreate]

could i make this without the resistor or the transistor? Will it make the led light up at all? At least a little flash of light?

[1up]

Nope, they are crucial components.

[ReCreate]

I got the Toroid and the (exact)Resistor,i did not expect to find the resistor anywhere but i did,and it still has long leads!(making it easy to solder torether)

[imakethings]

yes i made it thank you 1up(author)

[geeklord]

After about my fifth try it still doesn't work. I can get little flashes if I rub one of the leads on the battery. This is agrivating.

[ReCreate]

Is a toroid Ferrite? I am in a bit of

[ReCreate]

Sheesh...I was typing and then BAM Anyways,I am in a bit of a hurry And would like it to be answered fast

[dombeef]

Huh?

[ReCreate]

I was typing and then in the middle of typing the comment just was posted

[dombeef]

So what was the sentence?

[ReCreate]

it was continued in the next comment

[dombeef]

Ok

[imakethings]

will small toroids from the florescent bulbs work?

[dombeef]

Yeah

[neumanngregor]

i used the equivalent 546c and som bc107 i got rotting in a box :)) and it dident worked with a single cell but it worked with 2 ... like a normal wire and a 1k resistor connected to the blue led ... i tryed then with a red led and same result : it dident worked. i tryed with a nicd fully loaded 700mAh ACCU and same. i used for the coil a pair from a utp cable (the cable from e ethernet connection) ... the toroid is from a old source of a pc and is same size as that in picture (nearly as big as the battery) ... did i need a better wire for the coil or another tranzistor (i cudent find the 2N3904) or is this thing wrongly build ?

[ren7624]

Haha the pic on the first step, on the battery it says 'Alcaline' not alkaline go check it out it says 'alcaline battery'!!!!

[FeedTheGrid]

Well done. Good knowledge to have! FTG

[atombomb1945]

Does anyone know what you would have to step up for this to use something like a 9v Battery?

[1up]

What kind of LED runs on 9v? :P

[i make shooting things]

i found 15 toroid's in my old x-box!!!! as well as 2 Leds with super long leads and a bunch of transistors, and resisters (most of the leads are way to short i could solder longer ones but im lazy).

[Gr82Bake]

you can find them also in old fluorescent lamps (compact). just pry off the top part.

[1up]

Awesome! Are you going to make a joule thief with one of them?

[i make shooting things]

defiantly i just need the right transistor (radio shack). im thinking of putting it in a Altoids box.

[1up]

Post pictures when you're done!

[i make shooting things]

iv triple checked every thing and i cant get it to work. the Toroid has 22 gauge isolated wire i have the right transistor and resister. all the polarity's are correct. help?!

[1up]

How many turns did you get on the toroid?

[i make shooting things]

Sweet. I rewound the coil. using much smaller wire (13 turns v.s 9) and it works beautiful i even had enough power to light 2 4 volt Leds (ill make a slide show of finished project in addition to these:)

[1up]

Wow! 2 4v LEDs? That's pretty cool! So now you're putting it in an Altoids tin?

[i make shooting things]

yep and i finished the slide show its up now.

[1up]

Cool! That looks really nice.

[DELETED_Noah feasey-kemp]

(removed by author or community request)

[1up]

Any size will work, but I didn't know they had different densities. I'm assuming the densest would work best, or an uncolored one.

[DELETED_Noah feasey-kemp]

(removed by author or community request)

[1up]

Usually OK, if you wind your coil better it should work even better.

[lager]

i didt it and its not working i used a toroid thingy i got form an old pc psu and the wire im using from old ethernet cables, the transistor is npn 8050 idk what im doing wrong this is my third try with dif transistors and its not working . any help? thanks

[1up]

have you tried using a 2N3904 transistor?

[lager]

nope :P i allways try to use the things that i canivalize from dead electronic things but ill buy a 2n3904. thanks":D

[robotmaker]

couple of ideas if the joule thief doesnt work first only enamelled or magnet wire on making the turns on the coil if doesnt work switch wires on transistor side on transistors most have leds on npn emitter base collector,but some are different,look up spec to make shore what is the pin out is,and check if you have a bad one,most likely problems will be reversed wires on toroid coil

[leech223]

I did that, used different wires, and tried a NPN and a PNP transistor. I flipped them around and it still didn't work. What gauge of wire did you use?

[leech223]

does it matter if the wire is single strand or stranded?

[leech223]

Mine isn't lighting up. I tried using thinner wire and a different transistor. I also tried it on a bread board as well as soldering the whole thing together. The LED works. any suggestions?

[1up]

Perhaps the core isn't ferrite. Is it magnetic? Where did it come from?

[leech223]

Radio Shack. in a pack of 10. "Toroid Coil"

[robotmaker]

they should work good,read my last post on joule thief not working

[leech223]

Here it is.

[acmefixer]

Someone asked about the 1k resistor. It doesn't have to be 1000 ohms, it can be more or less. If you use a 2200 ohm resistor, the battery current will be less and the LED will be dimmer. For old germanium transistors, a 470 ohm resistor might work better. With a higher value resistor, the battery will last longer. The coil has to have inductance so it can store a charge in the magnetic field and then dump it into the LED when the transistor turns off. You can use a coil of wire with an air core. I wound ten feet of 24 gauge telephone wire on a spray can lid 2-1/4 inches in diameter. I then slid the coil off and taped up the windings. The winding had about 25 microhenrys inductance, which is enough for a Joule Thief. The telephone wire has two wires twisted into a pair, one is white with blue stries, the other is blue with white stripes. With a toroid core, the wire is much shorter and the resistance lower, so it will have less losses in the wire. And the coil will be much smaller, small enough to fit into the base of a flashlight bulb. You can't do that with a large air core coil.

[dombeef]

Does it have to be that exact 1k Resistor

[dombeef]

Hey can someone make a Iron man arc reactor joule thief? lol

[dyeniper]

thanks 1up! another question what's the purpose of the toroid bread ? what does this do to the whole circuit?help pls....ü

[1up]

I'm not sure exactly why it is needed, probably something for the magnetic inductance...

[RetroTechno]

The toroid bead is the core for what is a 1:1 transformer after you wind the wires around it. For more information on what's going on, read Colin Mitchell's explanation down in the comments below the article at the link that was in Step 4.

[Iridium7]

I am trying to get a pressure switch to run on a button cell batteries. the main power to the pressure switch is a 9-volt. Is this possible? If so how can I make this run and make it as slim as possible?

[revhead]

great Instructable, very well laid out and easy to follow. just a quick question regarding a toroid bead?? I'm not to sure what they are or what they look like, but I was pulling apart and old xbox controller that didn't work and in the long lead of the controller (original xbox controller) I found these two charcoal greyish cylinders that had the lead running through it. they are each about 2cm long, are these toroid beads?? thank you!!

[1up]

On the controller cord? Yes, those should be toroid beads. They're a bit longer that what I used, but they still should work.

[revhead]

thanks, i just need to buy the transistor. hey, do you know how long one (DEAD) AA battery could keep a LED lit?? and what would happen if you connected a new AA battery to it, would it destroy the LED??

[1up]

It should power the LED for several hours, and it will be fine with a full battery.

[dyeniper]

is there anything that can be an alternative to toroid bread??? because ive tried to do this with a magnet from speakers but it didnt work out.. the lead doesnt give a bit of light.. ders no availabale toroids in our place.. pls help

[1up]

Nope, there is no alternative. Sorry. Try looking in an old computer power supply, there might be some in other electronics, too.

[cheating-master]

how can i get a (Toroid Bead) to make this?

[1up]

You can get them in many places, from old computers or their power supplies, from broken XBoxes, and many other places. Or, you could just buy some.

[Padlock]

Nice Project. Just a question though; would there be any difference if you used a small Toroid Bead, and did, say only a few wraps, then if you used a huge one and wound it very, very tight? Anyway, again, nice project. I used the design to light a green LED in my "mini" light saber. It's made out of a car cigarette adapter and a mini hot glue stick. I had only room for one AAA. Oh, and 200th comment. Sweet.

[1up]

The bigger the toroid is, the bigger charge it can hold. If you made a really small one with few turns, it might not work at all. The big one would function normally, but it could be capable of higher pulses of electricity. (More voltage) Good idea with a mini light saber. I think I'll make one of those... :)

[Padlock]

I'd like to see a giant one of these, maybe like a modified battery rack and a 40W light bulb (one of those small, bulb-ish ones), run @ 12 volts.

[1up]

You'd need a giant toroid, and a high-current switching transistor, but I think it might work.

[raykholo]

if my power supply is 2 1.5v button cell batteries and the led works fine on 6 volts then do i need to add anything to the circuit?

[1up]

You have a 6 volt LED? Where did you find that? The joule thief does not multiply voltage, it steps it up. You'd have to modify the circuit a bit for it to work with a 6v LED.

[raykholo]

maybe im doing something wrong cuz its a bunch of ordinary leds i got from goldmine-elec.com and they work fine on 3 volts too so do i still need to change anything --- 3v power, 3v led ?

[1up]

Well, the joule thief works up to 3v and can power a 3v LED, so maybe you wound the coil wrong, didn't use thin enough wire, or maybe your transistor is broken. You used a 2N3904, right?

[raykholo]

nah -- i meant i was wrong about powering the leds, i didnt make this yet or anything what i am trying to do is make it a lot smaller so if you could give me an idea for the specs of the toroid that is made then i will get an smd one of those for a pcb.... thnks

[1up]

You can get really small toriod beads, I don't know where but they are extremely small and you need to use magnet wire with them.

[raykholo]

i was thinking about getting an actual toroid like below from here in the low profile smd toroids section (first 2 links)

its already put together and is ready for pcb mount , i just need info like the inductance, amps, ohms... any ideas?

[1up]

The toroid has to be a certain size to hold a charge. the smaller it is, the more windings it must have. Just keep that in mind.

[raykholo]

works 4 me -- ill post some pics if i figure the rest of this out and make it thanks

[ggiihh1]

what is an "equivalent" transistor? can one from any type of disposable camera be used?

[1up]

I don't know what kind of transistors are in cameras, but they will probably work. Any kind of NPN switching transistor will work. Equivalent means like a 2N2222, or a 2N4401.

[geeklord]

Why doesnt this work?!?!?!?!?!?!
^{its startin to piss me off......}

[1up]

Is that bare copper wire? It must be insulated. Try magnet wire.

[geeklord]

it's enamled(that was wrong), and ive tried stranded wire too, it doesn't work. Also I don't see how this circuit works, all you doin is shorting the LED with the transistor.......

[geeklord]

I've followed the circuit perfectly, Think it might be that my transistor is a P.O.S.?

[1up]

Perhaps, but the hardest part is making the coil, and that piece is most likely to fail. Get the thinnest insulated wire you can find and try re-winding the coil.

[geeklord]

I don't think I need that thin(although I will give it a try), look at his. Also I got a few flashes from the LED that looked like 2.5-2.75 volts so maybe my coil isn't holding a charge like it should.....

[geeklord]

(removed by author or community request)

[duckythescientist]

Let me try... A. about 1.5V B. a few bucks (4$ -ish) C. they are electronically operated switches (you need to just Google it) D. caps. are usually used to smooth an already somewhat regulated voltage (for instance if a power supply uses just a plain resistor to rectify AC into DC then the DC voltage will fluctuate and not look smooth if you were to graph it in a voltage over time graph. Adding a cap. will make the voltage more even. E. It is a crystal resonator used for timing in some computer and microcontroller circuits. When correctly powered they oscillate at a set frequency which is then used as the clock speed in the device. Your watch has one that probably oscillates at about 32 768Hz. I hope I've been helpful...

[kadris3]

a: they are different depending on the mfg. they vary from 1.2vdc to 1.9vdc. way less than other LEDs. 1.6vdc is average. start low and go slow.b: Perf boards depend on size. a small one can be a dollar up to any amount. c:that's like asking who you should marry. taste is up to the beholder. it depends on that which you are making. semiconductors traditionally save electricity and provide amplification for a circuit in use. they also make oscillators and buffers. depends on what you're trying to do. d:capacitors smooth out the DC ripple in a rectified circuit. they are used as an AC ground and blocking DC. they are also used to couple various stages of electronics. e: a crystal

[Sandisk1duo]

D) capacitors don't regulate voltage, they just smooth out the choppy output, get hook up the capacitor to the led, positive to positive negative to negative, and that should fix you up, altho it might NOT even light up (work)

[geeklord]

k, i thought i heard somewhere that they did. But what kind of capacitor for what kind of output?

[Sandisk1duo]

um.... you will need an electrolyc(big, circular can) capacitor, rated for 100-100,000uf, as a rule of thumb, you need a capacitor rated for twice the voltage you are using, so around 6v, i usually don't obey the rule, but i would for this, since the led lights up in pulses, i have no clue what voltage those pulses are, they might be 3-6 volts, so use a 6 volt cap. so ya, 100+ uf capacitor rated for 6v, Computer motherboards have a bunch of 2200uf 6.3v capacitors around the cpu, if you need to find some

[fallenspirit123]

will this work with a 680uf 10v capacitor?

[Sandisk1duo]

any voltage above 3v will work

[geeklord]

I've got a lot of electrolyc 100uf 6.3v capacitors, that should work right?

[Sandisk1duo]

connect them in parallel (plus to plus) you will get more uf, making the light stay on longer when you unplug the battery, then without any capacitor

[geeklord]

so if i had 100 of those caps connected in parallel to a AAx2 battery pack and an LED on the other end, I could unplug the battery and it would stay lit for a long time???? Oh, how my mind wonders.........

[1up]

Yes, exactly. ;)

[Sandisk1duo]

capacitors are like small capacity batteries, i don't know the ratio between uf (capacitors) to mah (batteries) i predict it's about 700:1
so yes, you can power leds with capacitors, but i don't see why you would build a joule thief for that aplication

[1up]

A) 1.9 v B) Not much, get it your local Radioshack. (Maybe $5.00) C) That's hard to explain. You're better off looking that one up. Different kinds work differently. D) I don't think they do, can someone help with this one? E) Like the guy below said, a crystal.

[thermoelectric]

Answer to e) A crystal i think

[LaxLuvr]

Do you have to use a resistor or is that just so the Led doesnt get too much current?

[duckythescientist]

The resistor is necessary but for a different reason. It is used to bias the transistor on but is designed to be large enough so that the coil can switch the transistor back off.

[pyro man]

is it possible to add a momentary swith to the circuit?

[pyro man]

oops i meant switch

[1up]

Yeah, easily. Just connect it between the battery and the negative wire.

[pyro man]

thank you very much

[joinaqd]

awesome job building this dude..i need some joule thieves in my cpu since i am a robot..

[pyro man]

wow

[pyro man]

im gonna do this but before i do it i will buy (single)AA battery holder to switch out batterys easier

[fallenspirit123]

Yo Brennen we should make a whole bunch of these and see how small we can get them to be like this one by big clive

[pyro man]

(in rough voice)lets do it

[fallenspirit123]

*response* Then we are go to go! *returning to helplessly nerdy voice besides I have some SUPER tiny toroids

[pyro man]

well need like 40awg wire too!!!

[fallenspirit123]

Im gonna try to get some magnet wire so we could build this

[pyro man]

ok remember the key word ''&appos;WE'''

[fallenspirit123]

ok so you need to get some transistors (2n4401,2n3904,bc337) andI need to get some magnet wire and I have a surplus of toroids :)

[pyro man]

done! ill come over sunday...maybe

[fallenspirit123]

lol ok

[bodybuilding_mike]

my first one works great, but i tried to make a second one today, using another toroid out of a psu, but it didn't work very well, the imput voltage was 2v (i had 2 dead AA hooked up) and the voltage across the led was also 2v im not sure what i did wrong, it is built right, i i think its the toroid, how can you tell if its the right kind?, this one is magnetic, but not a magnet itself ..does that matter? also what changes when you add more turns to the toroid?

[1up]

I don't think toroids are magnetic. That might be what's messing you up. Try finding another. If you wrap the wire thighter, you can add more turns. More turns means more efficiency. (Meaning lower voltages can still work. A very good joule thief can work to as low as .5v)

[ma_pignon]

does anyone know a way to prevent the transistor's legs from being pulled off (other than soldering onto circuit board)?

[1up]

Just don't bend them too much. If you bend them outwards just once, they should be fine. If you do it a bunch of times then they will break.

[ma_pignon]

ahhhh, I guess that's my problem. I have fidgety fingers : ) btw, whenever I turn on the joule thief, I always get a high pitched noise (like those mosquito ringtones) that really gets to me after a while. Is this normal?

[fallenspirit123]

I have heard that this sometimes happens (usally when using a big toroid) and it should be normal but If I were you i would check all the connections

[1up]

Some people are more sensitive to higher pitches than others. It might be normal, and only you can hear it, but my guess would be no. I don't know what might cause it, maybe that transistor? Maybe the toroid? I don't know. Try building another.

[masynmachien]

Thanks for this clear Instructable.
I used this in a Cyborg zombie feeding on "dead" batteries.
My Instructable includes a no-soldering construction.

[geeklord]

So could i just use a transformer with the same amount of turns on each side?

[1up]

I don't think so.

[geeklord]

That seems to be all the toroid is....

[atombomb1945]

Will you burn anything out if you use a new or fully charged battery in this?

[1up]

Nope. This circuit will work fine up to 3v.

[atombomb1945]

Thanks. Anyone know if this would be susceptible to magnetic interference. Thinking about using this as a Throwie Alternative.

[1up]

It night be. Have you built one yet? Try it and see if it still works.

[junits15]

is there such thing as a ferrite bead? because mine diddnt work right

[1up]

Are you sure it was ferrite? Try getting one from an old computer power supply. Also, you might have built the joule thief wrong, or maybe the batteries are REALLY dead. I've had a couple batteries that won't even light a joule thief.

[junits15]

well i know i built ir right and the batteries were in the perfect range, i tested them and how di i tell the diffrence between toroid and ferrite

[1up]

Toroids are usually made out of ferrite. I don't know how to test if it is real ferrite or not. If you took it from old electronics and it had wire wrapped around it, then chances are that it's ferrite.

[junits15]

well it was, mabey i broke the transistor while soldering.

[Pirate88179]

Can anyone tell me how to tell the collector from the emitter on the 2N3904 transistor? I think I might have a polarity problem of some kind. Great instructable! Thanks. Bill

[Pirate88179]

Got it...duh! There is a diagram on the back of the transistor packaging. didn't see it on the first one, but pulled the base out from too much bending and when I opened the second package...there it was............. Bill

[mike_d214]

Is there a inductor element that would work to replace the torroid / wire setup here? I'm looking for something smaller on www.mouser.com

[1up]

Not that I know of. But in the original joule theif (which can be found here) uses a VERY small ferrite bead. If you make one like his you can have a small joule thief like you want.

[Derin]

i know u used the inner wires from cat5,gimme my bonus points

[Goodhart]

Hey 1UP, thanks for the reminding me of this....I finally made one, boarded it, and put it in a box...... here is the forum topic....

[Anton1995]

I don't now anything about electronics so I have some questions:Will green LED work and will this transistor work ,on the back in says C547BW66. please replay . thanks Anton1995

[1up]

A green LED will work, but I'm really not sure about the transistor. If it's NPN, it should work.

[Anton1995]

I dont know its grey on the back,is that means anithing

[1up]

Not really. :/ You're best off just going someplace like RadioShack and buying a variety pack of NPN resistors.

[Derin]

what is the equation for the resistor vs voltage calc?

[1up]

Try this site:
http://ledcalc.com/

[Derin]

thx

[GorillazMiko]

Hmm. I have many of the same transistors that somebody sent me, and he wrote "NPN Like 2N3904" on it. On the back of the transistor, this is what is says:

_{7042
-02
M635}

Would that work?

[GorillazMiko]

Here's two images.

[bob.smitty]

they should work just fine if you identify the pinout correctly.

[1up]

If the writing is true, then they should work.

[GorillazMiko]

(removed by author or community request)

[Yerboogieman]

wow. too much mountain dew and skittles again? heres some sugar free skittles and some fructose, caffeine free mountain dew.

[Derin]

u are really hyper now,no more of that >£#½${_#$½½{#$½^{& candy}

[1up]

... Kinda freaked out, but ok... 0_0

[merseyless]

... ... wow ...

[lmsiems]

Where can u get a toroid bead no old computers around=(
ive heard u can get them out of cheap radios is that true?

[bob.smitty]

some modem cables have them, some monitor cables have them too... pretty much anything that has a "bump" next to one of the ends of the cable is almost guaranteed to have a ferrite nut like that.

[1up]

I've never taken apart a cheap radio, so I wouldn't know. :( Sorry.

[sandokan]

You can simply buy it, in an electronc store. I bought mine 0.4€ Cheap But it doesn't work " dunno why ,the "system" doesn't work with ... "dead" batteries. i've just tried one and it still doesn't work " it works only with charged batteries .. then it'sn't that interesting

[bbto]

look at the tutorial:
http://www.instructables.com/id/Take-apart-a-Compact-Fluorescent-Bulb/

it's not mine but thanx "westfw"

[bbto]

i found a toroid in a fluorescent light bulb X X DDDD X X D D X X D D X X D D X D D X X D D X X D D X X D D X X DDDD

[firdaus93]

I just want to ask something Bear in mind that I'm very new in electronics so I maybe will ask stupid question. What is the electronic component is in the picture ... Component A and the one on the right Component B

[electrophobia]

both these components can be resistors or inductors. U know we aren't the manifacturer of theese components :))

[1up]

I'm pretty sure they're inductors.

[electrophobia]

So don't be sure that much ;) i have seen many resistors which formed like the component on the left picture. So is the component on the right side a resistor?? Why not!

[Derin]

It may not be one,typically wire based resistors are mounted inside stone

[Derin]

evet o benim :)

[1up]

Hrmmm... I actually don't really know. Where'd you get the pictures from?

[firdaus93]

I have it at my house. It's from my dad's stuff.

[Estwald]

Some call this the "dead bug wiring" method of circuit assembly.

[steveo_mcg]

I've just finished mine, thanks for the guide nice and easy to follow. Quick question, how bright should this be? The led comes on but it seems to be running on a very low voltage, i think my toroid isn't wound very well (scrap cat5 threads probably weren't designed for this) but i'd like confirmation before i try to wind it again.

[1up]

Could you post a photo? Sounds like you need to use some better wire. :)

[steveo_mcg]

Thanks, yeah thats what i thought so I took apart an old computer psu last night and tried a prewound one from that but i think the wire was too thick. Nothing happened but the voltage at the battery dropped to about .5v from 1.3v so i presume the circuit still worked but the wire was wrong. Long story short took the old one off and it fell to bits, there is a transformer in there with lots of nice wire in it, going to see if i can salvage that and try again, i think the cat5 is too stiff so it doesn't wind very well around the toroid.

[steveo_mcg]

New problem, i've rewound it using salvaged wire from a transformer. Now however it only lights when power is removed or applied, so if i run the crock clip round the bottom of the battery it flckers when ever a connection is made or broken however if power is left on ie constant connection nothing happens except after a while the battery gets warm.

[steveo_mcg]

Never mind solved that one, had the negative connected to the wrong lead of the led.

[firdaus93]

Hi it's me again. I tried it but I can't get it to work. Here is the picture of what I did. But I already disassemble it

[Shrog]

It's difficult to see from the picture, but it seems that you made a mistake winding the toroid. In the image below, you seem to have the two wires at the red arrow both going downwards through the hole. At the green arrow it seems that the joined wires are both coming out the same side. Instead of both wires going through the hole in the same direction, you want one wire to go over and the other under.

[1up]

- Make sure the toroid is wound right. Remember in step 2, when you twist the wires of opposite colors together? Make sure you haven't twisted the same wire with itself. If it still doesn't work, try using thinner wire. I make shooting things got his to work with magnet wire.

- Make sure the transistor is a 2N3904, and that it works fine.

- Be sure you're using a 1k resistor. (Color code Brown-Black-Red)

- If you are unsure on how to put it together from the instructions, check out the schematic in the last step.

Hope those tips help.

[firdaus93]

Can't I just buy some component because is still can't get it to work. PLZ tell me if there is an electronic component because it will make it smaller too so it could fit in my pocket.

[1up]

Sorry, there's no component that you could use for this. :( You need to wind your own.

[firdaus93]

http://www.joulethief.com/kit.php

what about this ...
I found it today
if you can plz tell me all the
parts and a better schematic
I'm sorry to ask you so much but
I'm really busy with my exam

PLZ HELP ME !!!

[1up]

Yes, you could use that; It's a different circuit, but if a joule thief is all you want, then that should work well... Most people come to this page looking for a fun project to do. ;)

[firdaus93]

Can you plz give me a better schematic and the component. I'm really busy now. PLZ

[1up]

I can't give you a component... And good schematics are hard to draw! :(

[firdaus93]

No, what I mean is give the component list.

[1up]

Step One: Parts and Tools "Helping Hands (Optional) Soldering Iron Solder A Blue or White LED (Other colors are fine, too) 2N3904 Transistor or equivalent 1k Resistor (Brown-Black-Red) Toroid Bead Thin wire, two colors"

[thatonekid]

are you using an NPN or PNP transistor?

[1up]

NPN. A PNP equivalent of the 2N3904 is the 2N3906.

[theRIAA]

what does the 2N3904 Transistor do? I have no idea what it is....

[rickharris]

The circuit operates by switching the small DC voltage on and off very quickly. The equates to Alternating current and you can step up alternating current with a transformer (That's what the rig thing is) so you get an incerase in voltage (but a decrease in the available current). The transistor operates as a switch turning the current though the transformer on and off very quickly. As the LEDS will operate on a low current but need a voltage over 2 volts mostly this means they can be operate from a single cell battery. The circuit isn't all that novel having been around in several forms for a number of years. But it does work.

[lordguildor]

Not AC Pulsed DC

[phar]

hey, just wanted to add something here, the designer does deserve some credit here, while your right in saying that the concept isnt new, the design is clever in its minimalism.. the circuit.. is called a charge pump.. it does not however "equate to ac" the principle this uses to operate is a special property of coils called CEMF (or BEMF) .. "counter-electromotive force".. the short version is that as the coil has voltage applied across its windings it builds a magnetic flux that is proportional to the voltage applied (google "eli the ice man").. once that voltage is removed the magnetic flux can no longer be sustaind and collapses back onto the coil, the speed at which this happens causes a (again proportional) voltage to appear across the windings.. .. just thought that should be pointed out as it is _slightly_ different then a step-up transformer.. and the clever use of the second winding of the coil to actuate the transistor.. common give the guy his credit :) heck i might even build one as a dirty power supply for my solar projects with a big cap on it.

[Sandisk1duo]

what will happen if you leave out the resistor, just curious

[1up]

The LED will not light. ;-) Wanna know why? The resistor is like a "threshold"; it determines how high of a voltage has to accumulate in order for the transistor to turn on. The higher the value of the resistor, the higher the output voltage will be. If there is no resistor, the voltage will be extremely low, and the LED will not light at all.

[Sandisk1duo]

so your saying that i can get a 1mega ohm resistor on there and i will have high voltage at low pulses?

[1up]

Yes, but you'll need a huge toroid, in order for enough voltage to accumulate.

[Sandisk1duo]

so is acting like and inductor? and can't you use an inductor minus the coil instead of an inductor?

[lordguildor]

An inductor is a coil

[1up]

I don't know, can you? ;-P What are you getting at?

[Sandisk1duo]

my brain: logic+mechanical abilities

[1up]

Yes. As is mine. ;)

[pepsihog]

Great Instructable. It's a 'free-running' oscilator used as a step-up voltage converter. I can slightly remember an old project with a similar arrangement but it wasn't nearly as simple. The timing would probably have made it a Radio Electronics Magazine project, only I can't find it yet. The circuit operation is pretty neat. When the battery is connected the transistor is in 'cut-off' and no current flows in the primary side of the transformer. The Vbe (base to emitter) voltage of the transistor is usually thought of as being at least 0.7 volts, but that is for saturation. When the battery brings the base voltage up to about 0.3 volts or so it begins to 'turn on' and the transistor begins to draw current through the primary coil of the transformer. Since current cannot change instantaneously in an inductor it will generate a 'Counter ElectroMotive Force' (CEMF) against the battery voltage. Since the secondary coil is in the same magnetic field transformer action will generate a similar (not necessarily equal) voltage on it. In Step 4 of the Instructable the link has a circuit diagram which shows the polarity of the transformer windings. As the primary coil current increases, the induced secondary voltage will SUM with the battery voltage for an even higher Vbe, to drive the transistor well into saturation. This gives us a very low voltage drop across Vce (collector to emitter) for minimum power loss in the transistor. At this point one of two things happen; either the core saturates or the current reaches the maximum the battery can supply. As primary current stops increasing transformer action causes the induced secondary coil voltage to fall until the transistor Vbe reaches the battery voltage. But as the transistor falls out of saturation it's collector current falls too. The difference between the primary coil current and the collector current causes it's voltage to reverse, adding to the battery voltage until the LED forward voltage is reached and the current flows into it. As primary coil current falls transformer action induces a negaive voltage in the secondary so Vbe falls even more, maybe even to a negative value. Again this reduces power loss in the transistor by keeping it in 'cut off'. Eventually the current into the LED and the induced secondary voltage fall off so Vbe rises back to the battery voltage and the cycle repeats. Cool Instructable! One point I'd make is that you should only use primary battery cells. A secondary cell (rechargable) needs some power to remain to prevent unrecoverable chemical and mechanical changes within it. If a secondary battery cell is used it's voltage would fall well below this, until it becomes UNrechargable.

[1up]

Wow. Heh heh. You must know a lot about this, huh? And that last part: So THAT'S why they say not to completely drain rechargeable batteries. ;-)

[Tool Using Animal]

Curses, I've been too busy with tests and I'd been planning to do this ever since I found a ready source of ferrite cores, found in practically every house. Fate is fickle.

[CameronSS]

Hey, buddy, you can't just make a comment like that! Tell us your source! The Joule Thief...the only circuit I ever free-formed that worked without troubleshooting.

[westfw]

I'm betting Compact Fluorescent Light Bulb

[Big Bwana]

The burnt out Globe 13 watt CFL's work great use L2 for the wire just crack the core and peel the tape and pull off the wire, and then L3 is a nice tiny round ferrite core you can wind your transformer on, it even has a plastic stand off and solder pins you can use... and this makes it nice if your trying to stuff it in a flashlight ...

[Tool Using Animal]

Double dog darn you to the depths of Hades west ;-)

[trooperrick]

I found several ferrite cores in my old PC power supply, more than you'll ever need... not sure if thats what hes talking about though...

[PKM]

When dismantling an old LCD monitor for an abandoned lumenlab-style projector, I discovered that the signal wires to the panel are wrapped around a chunky-big ferrite core, presumably to filter out RF interference.

[thread 1]

all i could find was a 2N3906 transistor do you think it will still work

[Big Bwana]

just reverse the emitter and collector for a PNP, or find a real common transistor the 2N2222 or just 2222 works great..

[1up]

It's the PNP version of the 3904, I haven't gotten them to work.

[thread 1]

thanks

[Yerboogieman]

i swear anywhere i am thers gorillazmiko, its odd

[ma_pignon]

Do the ferrite beads found on the ends of usb cables work? They seem a bit elongated compared to the ones your using.

[1up]

As long as they're ferrite, it should work. I haven't tried them, tell me how it works!

[i make shooting things]

What does the toroid coil do in laymens(sp) terms, its an Inductor? right?

[GorillazMiko]

Smart idea, and a very nice job you did. I didn't know a AA or AAA (can't tell) could power an LED. And what do those ring things do? I never actually figured that out. Nice job! +1 rating. (added to favorites)

[PKM]

The ring thing is a core for making in inductor, which is kind of like a capacitor in reverse- it stores energy in the form of flowing current, not separated voltage. I know that description is about as clear as compost but without going into electromagnetic field theory it's a little hard to describe. There's a neat parallel between capacitor-inductor circuits and masses on springs- a capacitor is like a spring, an inductor is like a mass, and the way they react to force and store energy is roughly equivalent. With two coils around it it acts as a rudimentary transformer, so in this case it stores energy from the battery and then releases it in a pulse at a higher voltage to power the LED when the battery coil is switched off.

[teaaddict314]

hasnt this already been done before?

[comodore]

Yes, on make podcast.

[Kiteman]

1up credits the source.

[Kiteman]

Nice job, but why "Finally on Instructables"?

Cat Burglar
Joule Thief Torch

[1up]

Maybe I should change that, but I meant the individual project, not built into something else.