Joule thief's....? Answered

Do all the components make a difference in the efficiency of the joule thief? i.e type of transistor, resistor, capacitor...

Question by ML159   |  last reply

Joule thief?

Is there a joule thief capable of powering a 3 watt LED at full brightness? Or just over 300ma output average?

Question by .Unknown.   |  last reply

Joule thief? Answered

Http:// : It was from here that I built my first working joule thief. (I've found better ones now.) Anyways, last week, I got bored and tried to destroy an LED by feeding the circuit more and more power...I got to 18V (laptop charger adapter) and it still didn't bust. Why?

Question by .Unknown.   |  last reply

Joule thief is not working. Answered

I just made a joule thief and my led is not lighting up. I put a single AA and it wont power. My led does though require 3.6v and i gave it 3.7v for a few seconds and the transistor became extremely hot. Is there something i am doing wrong? I have a 1k resistor, a 2N2222 transistor, a led that requires 3.6v and 30ma, regular wire 26 awg, and a toroid bead.

Question by Munchys   |  last reply

Joule thief is not working?

Learned about the Joule Thief from Make's Magazine and used their schematic. I'm pretty new to electronics so I don't know much about components. Applying 3 V, the LED lights up, but applying 1.5 V, no light. Green wire is 22 ga, blue wire is 26 ga. Using a 2N3904 Transistor and a Ferrite Toroid. I think I "barely" got the LED to dimly light up, but it would not stay on. Am I doing something wrong? Picture available in second comment.

Question by gera229   |  last reply

Joul thief how to? Answered

I've been reading some ibles about joul thief making, and most of them teach how to power an LED with a 1.5v AA battery.  That is great, if you want to power an LED with a 1.5v AA battery :) But what if I want to keep using old, weak AA batteries, as 1.5v batteries?  How do I make a joul thief that takes whatever the battery can give it, and outputs it as 1.5v?  I know the kind of transistor, ferrite core, number of windings and wire gauge all affect output, so how do I know what to use? Thanks!

Question by Morgantao   |  last reply

My joule thief Lights my LED for a second then dies, can anyone help? Answered

My joule thief Lights my LED for a second then dies, I could only make it flicker by scratching two of the connections. I've used three different transistors but received the same result. The transistors were kn2222, pn2222 and 8050 (couldn't find Bc547,2n2222 etc). I had 18 loops around the toroid and a 100 ohm resistor, is there anything wrong with this and can I fix it?

Question by Zithe   |  last reply

joule thief: can i use a cellphone battery charger to power a joule thief? output 5v~ 400-600mah. Answered

What resistor should i use? a 1k resistor,220ohm or a variable resistor/potentiometer B50K is ok?  masters help pls.. im noob

Question by reopoop   |  last reply

im trying to build a joule theif but im not very experienced can somone help? i need dimensions aswell?

The only place i can get the components is maplins can somebody link to the right product or give me the dimensions? thx

Question by wizzywoo   |  last reply

How would i used a joule theif and power 10 to 50 led on a circuit if i used a 5v power supply or a battery.?

I wuld like to make a banner out of leds for my wife and i am wondering if it would b possible to do it using the joule theif method but instead of a battery use a 5v power supply. wat resistor wuld i need and is it even possible?

Question by tak332   |  last reply

Can this be a coincidence? Do they look like two independent designs? Answered

I came across this kit when I was browsing the web. What surprised me is the uncanny resemblance to my design published here in Instructables. I'd like to know what you guys think about those two designs. Do they look like they are created by two independent designers? Can someone design a product so similar to another without copying the other? (The kit in the front part of the picture is taken from Eastern Voltage Research website. The photo is photoshopped by them since yesterday to remove holes on the end of the PCB which accomodate home made battery clips.) Please post your opinions! Thank you!

Question by ledartist   |  last reply

joule thief without resistor?? Answered

I want to make a joule thief,  but I don't have the 1k ohm resistor, so what can I use instead? or will it work without the resistor? Thanks for answer!

Question by aninda13   |  last reply

How to build a joule thief? Answered

      I'm building a voltaic cell and a joule thief. I searched on some instructables and followed the one on youtube by MAKE:. When I hook up a 9V for a few seconds (To not burn the LED out), it works. However, a AA doesn't work. Not even a brand new one. So, I presume that I haven't wrapped the toroid around enough to create more voltage and lessen the amperage (If that's what joule thieves do)? I posted some pictures below. Also, I'm looking to buy a voltmeter, I'm around basic level and just need to measure if the joule thief is even increasing voltage (For now at least). Here are some cheap ones I'm looking at on amazon: Some of those have autoranging, is this to automatically find the voltage/amperage? Thanks, please reply

Question by knexpert1700   |  last reply

Joule thief 12VDC 3A?

Is it possible to build a joule thief to run a netbook? I mean feeding the circuit with a 9V radio battery and to have an output of 12VDC 3A.

Question by laurieddhru   |  last reply

A More efficient joule thief Answered

I need to make a joule thief type of thing that can up the power from a 0.55V source to a simple LED. I know that the joule thief is not the most efficient circuit which is why I am asking if you know of an efficient circuit I can use.

Question by physics_dude   |  last reply

Joule thief running a CFL?

I've seen a lot of videos of people making joule thieves to power CFLs, with only one or two cells. (These actually work, right?) However, most of them require large (larger than a soda can) inductors and/or ignition coils and transformers. Is there any joule thief (or circuit) out there capable of running a CFL at full brightness, with around 6V, but at the same time being as small and uncomplicated as possible?

Question by .Unknown.   |  last reply

Jule thief transformer issues. Answered

I'm trying to make a Jule thief, I set up the circuit and tested it using a salvaged transformer and it works fine the only problem is that the salvaged transformer is kinda large. So i decide to try to make a smaller transformer using a Radio Shack T4452-1R2L choke and 26 gauge magnet wire. i managed to fit 15 pairs of windings onto the T4452-1R2L Toroid, but when i tested it the led won't light up. I tested the wires for shorts using a multi-meter and even tipple checked that it was wired correctly. Is this Toroid just not suitable for use in transformers of this kind or do i need to use a smaller gauge wire or is there something I am overlooking?

Question by FrozenKnight   |  last reply

how does a toroid in Joule Thief circuit work? Answered

Sorry for the noob question, but i can't understand how a toroid can cause a LED with higher voltage than the source to be lit.. i tried to make it without the toroid (only the transistor) but it didn't work... any explanation is much appreciated.. tq..

Question by firdaus_alizh   |  last reply

Can I make a joule thief with Pnp transistor?

I  was making my joule thief recently and I could not get success. I found out that I have Pnp transistors and that's why I am wiring them wrong. Can anyone provide me with a schematic to make it with Pnp transistor?  Thanks for your help!!

Question by aninda13   |  last reply

I need help on to make a joule thief? Answered

I had made tons of joule thief, but the biggest problem is at beginning I had faced one problem, which is whenever I make it it can light up the led after some shaking,, (shaking causes some wires to touch the other in a way that is correct I guess).  But I follow the schematics, and then I finally made on that worked better, and without any toroid bead, but now with the new transistors I bought, none of them work anymore,  my old transistors got lost. so what can I do? 

Question by aninda13   |  last reply

joule thief won't work for me, can't figure out the problem

i made joule thief as shown everywhere in instructables, I tried few different transistors, and toroids, I had like 100 tries, and can't get it to work? and: can I use transistors-in the middle of the last picture?

Question by xtony666   |  last reply

MXDL 3 watt joule thief? Answered

Can anybody make sense of the joule thief inside a MXDL 3 watt luxeon torch? I can post a rough picture of it if needed.

Question by .Unknown.   |  last reply

Joule Thief w/ 555 timer

Hello, I have a question about using a 555 timer with a joule thief. I'm trying to build a circuit for some solar powered bike lights but I have a couple of questions... 1. Am I correct in assuming that it's a bad idea to try to run a TLC555 timer chip from the output of the joule thief? Without a load, it seemed to be pumping out at almost 80 volts. 2. I tried building the circuit so that the two rechargeable 1.2V batteries would power the 555 directly, and then the output would sink and source two transistors alternately, which in turn would switch the LEDs alternately, using the output from the joule thief, which was also powered directly from the battery. That resulted in no LEDs lit and some very hot transistors... Bad idea. The TLC555 chip is supposed to run on a supply voltage of 2-18V, but when I tested it with the 2.4V coming from the batteries, it would source, but not sink... Is there any way to build this circuit so the 555 could blink 2 LEDs alternately while the LEDs are powered by the joule thief? The only alternative I can see that might work would be to power the joule thief from the output of the 555 and just blink all of the LEDs at the same time from the joule thief's output. Any help would be appreciated!

Topic by amklose   |  last reply

Efficient/High output Joule Thief?

Right now, I am looking for schematics for the most efficient (1 cell and 1 LED) joule thief, to use as a durable reading light. I right now favour Quantstuff's 2 transistor SJT ( but I am not sure whether it is the most efficient. I've seen several others, but since they all claim to be equally as efficient, i'll have to rely on the experience of other tinkerers and hobbyists. So: what's the most efficient or high current or high voltage joule thief you know of?                                                                                                                          Thanks.

Question by .Unknown.   |  last reply

Anyone interested in a stator joule thief? Answered

A few days ago I made a few joule thief ornaments from motor stators and rotors (pictures on my blog). I was wondering if there is any interest in an instructable detailing how to find the right wires on a motor and generally how they can be wired/rewired for joule thievery. Since my recreational project focus is capricious at best (and my blog is very young) I've put the question here rather than there. Alternatively I could write an instructable on the process of making a specific joule theif with a stator, but I would have to not include sections on different types of motor for clarity's sake. So if you have a preference for one or the other, or an interest in the idea, I would appreciate any input. Thanks, Drew

Question by andy   |  last reply

Does a joule thief consume power without a load? Answered

I want to add a joule thief to a battery so it always puts out 12 volts regardless of the charge level but i don't know if it will constantly drain the battery. I am also wondering if anyone has ever used a joule thief with a wind generator to charge batteries.

Question by AlbinoMoose308   |  last reply

can a joule thief be used for a 6 volt incandescent lantern? Answered

I want to use a joule thief to increase the lifetime of a lantern battery. I want to use the incandescent bulb, it has more power than leds. I plan to have one lantern for new batteries, and one for used batteries with the joule thief.

Question by cb92   |  last reply

Does any one know how to make an Ne-2 joule thief ??

Recently I’ve been researching on how high voltage joule thief works. The popular high voltage joule thief videos out there are known as Jeanna’s light if I’m not mistaken. I also built my own little LED joule thief circuit, it appear success after all with a 2n3904. But I want to take the concept a little bit further, so I decided to attempt on the high voltage joule thief circuit. It appear no luck, I have 120 turns for high voltage on my ferrite core (1 turn = 1 volt). I know it’s the same principle as the LED joule thief but with the LED removed. I have two 1kohm resistors and I connected them in parallel to get 500ohm resistance. I connected them all like the LED joule thief, but it seems like I did something wrong.  So I ask for further instruction. Parts that I use: 40 or 30 gauge magnet wire (high voltage windings) 20 gauge magnet wire 2n3904 transistor (Don’t know if that’s the right transistor for this circuit, but it’s for experimental purposes only.) 2x 1Kohm resistors in parallel = 500 Ohm resistance AA rechargeable battery. The thick magnet wire are 7 turns.

Question by BlackWolf1024   |  last reply

my solar setup wont work with my joule thief, it just bypasses it. why?

I got a few solar cells wired up in a series to produce around 4 volts, so to get more power from it i connect it to a joule thief i made but the power goes through it and isnt boosted at all. the joule thief works. at 1.5volts it makes around 5 volts. so i cut the power on the cells to 1 volt thinking im overloading the circuit but it is still bypassed.  i even connected a couple of capacitors to the solar cell to trick the joule thief into thinking the solar cells are a battery but still no luck. my question is why doesnt the joule thief boost solar cell power but will boost a dead AA battery?

Question by florlayamp   |  last reply

"Joule Thief" LED Night Light Kit is Now Shipping

Thank you so much for those who pre-ordered the kits! I have shipped all orders now, and the kits are in stock. New orders will be shipped within 2 days. To purchase, please go to Please see this post for the pricing and more: Thanks!

Topic by ledartist   |  last reply

How long does a "Dead" battery last in a joule thief?

How long would it take to suck all the juice out of it?

Question by Zem   |  last reply

How to make Joule Thief with Multiple LED and maintaining its brightness.

I've seen people running 61 LED or 100 LED on Joule Thief (1 AA Batt) with its full brightness. How did they do it?? I know how to build Joule Thief I have: -NPN   2N3904, 2N2222A, 2N4401   Transistors -Resistor   what I have now 1K, 560, 100.. -Toroid 12 turns and 20 turns -LEDs! -Batteries! Can anyone tell me what to do to run at least 10 LEDs with good or full brightness?

Question by jaesungauzakim   |  last reply

Is it possible to charge a mobile phone from a lemon? Answered

Im thinking, lots of electrodes in one lemon, joule thief and a capacitor maybe...?

Question by dalbyman   |  last reply

Joule thief from Answered

The joule thief from this website was the first working one I built, mainly because I'd favoured one without a tapped inductor. Anyway, I pulled it out a couple of days ago, and started poking around with it. I noticed that if I put a 10uf  (or maybe it was 1uf or 100uf, sorry, I don't remember) capacitor in parallel with the 0.001uf capacitor, the LED would start to flash. this would not happen with any other value however. Why does this happen? P.S: I've heard that this joule thief is poorly designed. Is this true?

Question by .Unknown.   |  last reply

6 volt LED lantern joule thief

I'm about to embark on a project to build a joule thief to power my new 6 volt LED lantern. I'm going to replace the lantern battery with the same volume of half dead AA batteries, which I have a bowl-full. My mice and cameras reject the AAs when they are only half done. The joule thief should finish them off. My question is if I might be just as well off to wire my AA four battery packs in a series/parallel circuit. First start parallel, then series as the batteries run down. This would give me a high/low control for the light, too. The joule thief will only draw the batteries down so far, and the LEDs have a low voltage threshold. Since the light is engineered for six volts, I'm just wondering which way to go.

Question by cb92   |  last reply

Wave JT Kit - LED Chaser with Joule Thief - Sale

Wave JT is an LED chaser/Larson scanner/sequencer what runs with just one AA battery. Joule Thief circuit boosts the 1.5V (or less) from the battery to 5V to power the microcontroller and LEDs. The kits are available at $19. PCB alone is $7. *** Summer Sale Price *** > see the instructable > go to my website for purchase

Topic by ledartist 

Could I use a joule thief to power 2 super bright blue leds?

Using this instructable's instructions, would it be possible to run 2 blue led's off 3.3 volts? I'm using a 3.3 volt logic system and I need to have 2 blue led's light. Also, how do I know what resistor to use for this? And could the led get too much voltage and be blown? Sorry I have so many questions. I've just never used a joule thief!

Question by 4lifenerdfighter   |  last reply

12v joule theif from 1 AA Answered

I need to make a joule theif that can output 12v to power some rgb leds. any help would be great. but preferably in the form of a schematic. i have all of the parts needed.?

Question by aduy   |  last reply

I want to make a joule thief to power a 10W LED (833ma @ 12v) from ~2 AA batteries, suggestions on toroid ? # of turns ?

My transistor inventory: Part #          Package TIP122       TO-220 TIP32          TO-220 2N2222      SMD 2N3904      TO-92 2N3906      TO-92 C1815        TO-92 BC546        TO-92

Question by yaly   |  last reply

Where can i find a ferrite toroid for my joule thief? Answered

Where can i find a ferrite toroid for my joule thief? Iv'e opened almost all the devices in my house!!! Just wanted to make a simple joule theif. I dont have any CFL's to open.

Question by TheMasterThingMaker   |  last reply

"Joule Thief" LED Night Light Kit & PCB

UPDATE: Everything is shipping now. My instructable is here: "Joule Thief" LED Night Light  Check out the new color changing Joule Thief! KIT Pricing is $10.50 for the kit. Kit 5 Pack Save by ordering 5 packs for $39! PCB Pricing is $4.50 for the PCB. Shipping is $5 for USA, $17 for the rest of the world. *** NOTE: The color of the PCB will be green instead of purple shown in some of the pictures. *** Payment To order, please go to my site - Click on "Add to cart" button and check out via PayPal. Please send messages or leave comments here if you have questions. Thanks!

Topic by ledartist   |  last reply

I need help on my joule thief circuit that won't function. Answered

I've been attempting to construct a Joule thief circuit but it appears the circuit won't function, even with the essential parts that I scavenged from a CFL bulb. The parts are: 112dl transistor, LED, ferrite core, 1K ohm resistor, 1.2volt rechargeable AA battery and magnet wires, 14 turns on the core and  I attempts to switch the connections on the wires, it appears no hope. I've watched all the tutorial videos on YouTube but appears to be failure. If you found a solution to resolve this issue, please explain it specifically. Thanks !

Question by BlackWolf1024   |  last reply

LED Artist kits now available at The Maker Shed!

Two of my kits: USB Blinky and Colour Night Joule Thief kits are now available at The Maker Shed ( USB Blinky @ Maker Shed: Colour Night Joule Thief @ Maker Shed: Please check them out!

Topic by ledartist 

Joule Thief Toroid not helping to step up, Why? Answered

Hey fellas..I am having problems with joule thieves especially with the toroid part.... First time I wound my Ferrite Core and the joule thief ran smoothly... But recently I had to unwind it to try other wires which didn't work.. So i again wound up the toroid just like the first time when it used to work but unfortunately this time it didn't work... I have checked everything and found that the only problem is that the toroid is not helping to step up the voltage.. When i applied 9V across it, the LED glowed but for 1.5V it didn't. So there is a problem with the toroid.. But what it is and why is it happening I don't know..I mean for the same core and same style of winding once it worked and now it doesn't, Why ?? Can anyone help me ??

Question by Arijit Chatterjee   |  last reply

Joule Thief in between Peltier/TEG and DC Motor?

As per the title I've got a Peltier cooler chip sandwiched between 2 heat sinks acting as a Thermoelectric generator (TEG) which when sat on my wood burning stove generates about .5V (which is a bit disappointing).  The idea was to cheaply recreate one of the EcoFans, so the plan was to connect the TEG to a low voltage DC motor.  The obvious issue is the low output from the TEG itself - I need to maximise the heat dissipation from the top heatsink to create the temperature difference, but even solving that I'm going to struggle to consistently get more the 1V from the TEG. Before I go to the hassle of sourcing and making a Joule Thief (like the 1up instructable) is there something fundamental I've missed that means either the TEG won't work with the JT, or a 1.5V - 3V DC motor won't work with the JT? Appreciate any help is establishing the feasibility of this idea, or suggestions to an alternative solution :-)

Topic by thankyousam   |  last reply

high capacity joule thief/dc-dc converter

I'm trying to make a dc-dc converter with the following characteristics: Output = 5V regulated at up to 30mA = 150mW Input 1V (or lower) from a slightly flat AAA. Assuming a pessimistic circuit efficiency of 50%, then the input current would need to be 150mW / 0.5 / 1v =  300mA which I think a AAA is capable of supplying. I'm using a variation of "led torch circuit 2" from, but I've replaced with the 1n4148 with a schottky diode and replaced the 2 LEDs and 29R resistor with a 5k6 and 1k resistor respectively; this should limit the output of the circuit to just under 5v. I have a 150R resistor to provide a 30mA load to the circuit. When the input is 2.4V, the output is 4.62V which is close enough to 5v for me.  But if I decrease the input voltage to 1.14V, then the output voltage falls to 2.7V which is not enough. I have tried half a dozen hand wound transformers with various turns ratios, wire thicknesses and shapes (slug and toroid) but am unable to achieve 5v out (at 30mA) from 1v in. Does anyone have any suggestions as to what to adjust, or perhaps a better circuit?

Topic by GrotBox   |  last reply

Joule Thief. I know how they work, but is a joule thief self-regulating and self-limiting? Is a varying input (DC) okay?

Joule Thieves. I know how they work (my one works fine) , but is a joule thief self-regulating and self-limiting? Could I hook it up to a 12V source? Is a varying input voltage okay? -- Will the voltage/current across my white LED (should be 2.6VDC absolute max) be too high or surge? I would like to know if it would be suitable to use on my motorcycle to drive an additional LED or two for a headlight supplement. The voltage varies between 11.5VDC and 18.2VDC. I have a basic handmade circuit, with a hand-wound toroid and a generic transistor, usually running from a stable 1.1 to 1.6VDC, I have tried it with a 9V cell and it seems to work alright, but I want to be sure before modifying it/or my motorbike. Any help much appreciated! 8-)

Question by xerxesx20   |  last reply

what is the cheapest way to make a AA joule thief HV?

After trail and error i have made a joule thief with the following: 2n3409 transistor, 1k ohm resistor, led, and an air coil. what would i need in order to boost the power up to say 100v or more? the cheaper the parts the better, at least for now. I've read some what about micro controllers and using 2 555 times, but i am unable to use anything that requires a computer. everything needs to be simple enough to be used via a bread board. I am desiring high enough frequencies and voltage to jump a small spark gap. i am aware the spark is waste, but that is the point.

Question by freenergyfuture   |  last reply