Try it Out!

Step 4: Try it Out!

And that's it! You're finished with your Joule Thief. Touch the twisted wires coming from your toroid to the positive side of a battery, and the extension wire to the negative side. If all is working well, the LED will light up! If not, try using thinner wire on your toroid. I've included a schematic in the pictures if you prefer.

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Jollyrgr says: Mar 31, 2013. 11:46 AM

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.

rabitt says: Feb 23, 2013. 7:53 PM

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

echuzzzzcute says: Apr 7, 2012. 2:43 AM

can i use hsd965 for transistor?

Ray Power says: Oct 19, 2011. 5:05 AM

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

robot1398 says: Dec 26, 2010. 7:21 AM

can i use a bc547 transistor in place of 2n3904

-max- in reply to robot1398Jun 5, 2011. 6:24 AM

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 in reply to -max-Jun 5, 2011. 7:46 AM

i made it with bc547 and works better than 2n3904

-max- in reply to robot1398Jun 5, 2011. 2:06 PM

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

robot1398 in reply to -max-Jul 20, 2011. 7:58 AM

then how did u know the pinouts

robot797 in reply to robot1398Dec 26, 2010. 2:20 PM

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 in reply to robot797Feb 21, 2011. 3:19 AM

thanks

RONEDOGG says: Jul 14, 2011. 4:21 PM

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 in reply to RONEDOGGJul 17, 2011. 11:00 AM

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 in reply to S33PlusPlusJul 17, 2011. 11:18 AM

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 (author) in reply to RONEDOGGJul 17, 2011. 9:57 AM

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 in reply to 1upJul 17, 2011. 10:14 AM

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 (author) in reply to RONEDOGGJul 18, 2011. 9:18 AM

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 in reply to 1upJul 18, 2011. 10:20 AM

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 in reply to RONEDOGGJul 17, 2011. 11:06 AM

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 says: Jul 12, 2011. 3:35 AM

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.

jhao says: Jun 8, 2011. 11:15 PM

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

ShemySheza says: Mar 6, 2011. 5:24 AM

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

-max- in reply to ShemyShezaJun 5, 2011. 6:21 AM

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 says: Jun 3, 2011. 6:53 AM

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

-max- in reply to jtodJun 5, 2011. 6:17 AM

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 (author) in reply to jtodJun 4, 2011. 1:17 PM

Where did I say this would charge the battery?

rayfalcon says: Nov 21, 2010. 6:20 AM

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 in reply to rayfalconJun 4, 2011. 7:16 PM

I think it's a zener diode

1up (author) in reply to rayfalconNov 21, 2010. 9:49 PM

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 in reply to 1upJan 7, 2011. 12:39 AM

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

lperkins says: Mar 5, 2011. 10:55 PM

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.

rhanson294 says: Dec 1, 2010. 8:07 PM

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 in reply to rhanson294Dec 6, 2010. 12:56 PM

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

thomas53 in reply to luiscllDec 21, 2010. 7:24 AM

Or just use a battery holder

threewheela in reply to rhanson294Dec 4, 2010. 10:29 PM

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 (author) in reply to rhanson294Dec 2, 2010. 7:07 PM

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.