Picture of high voltage joule thief!
3v glw 005.jpg
3v glw 011.jpg
this is how to make a high voltage joule thief!
the ones i made were 90 and 180v but the more
hv turns you do the higher the voltage(about 1v per turn)
this circuit runs best @2.4v-3v

Step 1: Materials.

you will need:
toroid core(ferrite)
2n3904(sometimes others work too)
512ohom resistor
winding wire(0.15mm approx)
0.2-4mm as well!
neon glow lamp (i used maplin rx70)

For Safety procedure Try to Put Fuse in HV LEad

:D really? hv output is very, very low current so it can't blow fuse

eyal_hadar made it!8 months ago

is that the same?



מצלמה ישנה 038.JPG
imakethings6 years ago
what is the output voltage?

Mine is 100v can shock Human

Step 1 "the ones i made were 90 and 180v but the more hv turns you do the higher the voltage(about 1v per turn)"

Try to Short Circuit hahahaha

cool (y)

legionlabs2 years ago
This is a perfectly good circuit, but you don't actually need 2 coils.

If you use the original joule thief design, add more turns of thinner wire, and choose a good value for the resistor, you can get the same voltage range. This way you save yourself a little work and wire.

Quite by accident, I got a standard joule thief to produce 100v from a 1.5v cell with about 50 turns of wire, a 2N2222, and a 500ohm resistor. More turns of wire should increase the output voltage.

To those getting 0v output: you probably connected the wrong ends of the coil together. If you were to connect the "start" of one wire to the "end" of the other, that would be correct. Otherwise, your transistor won't oscillate and you get no output.

The usual precautions for working with higher voltages apply.

That's actually a bad idea. it exposes the transistor to the high voltage output which will kill it after a while. its better to build it this way and put a varistor on the output to prevent it from getting burned out if you turn it on without a load.

Quite correct! Still quite fun for a 0.07$ transistor though!

can you post the specifics and schematics for you 100v joule thief? it sounds very cool. an ible would be great!

Effluxmind1 year ago
Nice! Joule Ringers are interesting little circuits. I use one when I need > 30 volts for finding negative pins on fly back transformers.
For some reason I can't get mines to work, I measured the voltage it was out of range on my multimeter set it to AC, but it doesn't light up an neon or so. It lits up a LED without a sweat. The parts I use is a toroid core, 85 turns of HV, 10 turns on the LV 1 and 5 turns on LV 2, NPN 2n3904 transistor, 500 ohm parallel resistor. I've tried 5 turns on the LV 1, but it doesn't seem to work. I use 2.4 volt as an power supply.
baven3 years ago
Hello there i got problem with this circuit. I got exactly same setting as you with same turn ratio same resistor and transistor and voltage too but when i insert the batterys i get no voltage on the hv output. Any suggestions where could be the problem ?
Hello, have hit the very frustrated stage?? Have built a tiny 8t Bi-fil version which worked fine -same transistor as in your set up......I have since made your version and have had no luck-only that the transistor starts to head gradually.....I'Ve used [2] different ferrite's and thicker wire----?????????? Anyone have any suggestions

:-Have done some research as some ferrites have low or high Hysteresis -understanding that some saturate with magnetic field and some enhance field strength /Flow.....?
NatureTM3 years ago
Thanks for the example. Multimeter shows 500V, however not enough current to light the neon bulbs I have on hand. Skin test doesn't produce a shock feeling either. I'm going to school for CE and just finished my "circuits" class. Armed with my incredibly basic knowledge, I would guess this power supply has an extremely 'high internal resistance.'
wateenali3 years ago
hi there thanks for this great tutorial.I made this circuit and it generates high voltage but the current is too low and it unable to lightup the led bright i cant understand i check the voltage on the meter and it is more than 500v.Please help to solve this problem.
thers no current the thin your hooking it to drops it drasticly giving 3-6 v off
raja264 years ago
I have tried with a thick wire for high voltage output and a much thicker wire for low voltage input.. It works very well.. I didn't connect a resistor though, it can run two 3V LEDs with a single AAA of 1.2V..

The only problem I've got is the heat that builds up in the transistor(2N5294). My another doubt is, whether we could modify the setup to run a dc motor, like simple rectifiers or something.. Thanks for the great instructable. Been searching for a guide to increase DC voltage.
Alex1M6 raja264 years ago
Adding a resistor to the base might help with lowering the amount of heat the transistor produces.
raja26 Alex1M64 years ago
Hi Alex, Thanks for replying. I have figured it out by myself. But can you just tell me how I can run a DC motor with it.
Alex1M6 raja264 years ago
Could you try placing the motor in place of the LED? If it does not run use a 3v input with two AA battery's in series.
raja26 Alex1M64 years ago
Thats not possible, because the motor runs with just the battery itself, so when using the Joule thief setup it should be working normally. But the output from joule thief is a pulsated DC. I have to convert it to pure DC for making it work. I just want to know what type of capacitor and inductance to use it as a filter for the DC output.
Alex1M6 raja264 years ago
Oh, in that case you might want to try adding a capacitor across the motor terminals. Try different values and see what results you get.
I believe a simple ceramic disk capacitor will do.
Thanks for the relpy Robot Lover. I'm a zero in electronics, so I don't know about these ceramic capacitors and all. All I can do is try some Random Capacitors.
Alex1M6 raja263 years ago
Hi, Sorry about my comment. I just assumed you had electrical knowledge, I tend to do that sometimes with people.

Have a look at the image I have attached it will show you a ceramic capacitor in parallel with the motor and give you an idea of what to look for.
raja26 Alex1M63 years ago
Wow, thanks for this quick help.. By the way, what will be is capacitance?.. This is a fair picture.. Much needed help indeed..
raja26 Alex1M64 years ago
Yeah, thats what I'm looking for but is capacitor alone is enough? Don't we need inductance?. I don't know much about capacitors so please specify some value for that one 1.2 V AAA battery.
PKM6 years ago
Do you know what the waveform of the output looks like? Are the edges sharp enough to drive something like an ignition coil? I'm thinking of something like this- battery powered Jacob's ladder FTW :)
12V (author)  PKM6 years ago
the first picture is when under no load and the second is with a neon wire ended lamp.
iiiiiiiiiiiiiii 002.jpgiiiiiiiiiiiiiii 001.jpg
ramatern 12V4 years ago
OK, now I'm interested. What I'm looking at is a sine wave. Why can't I get an inverter to give me a nice sine wave like that? Can I adapt this to function as an inverter? ;-)
PKM 12V6 years ago
Awesome, O-scope traces- I was half expecting a response along the lines of "WTF are waveform edges" or "no" or something. Still, that looks like a "no" because it's near sinusoidal with a load on it. Oh well.
Xellers PKM6 years ago
555 timer
12V (author)  PKM6 years ago
i do know of another circuit that is a load of dc pulses
but i haven't got o-scope traces because mine broke so i have to make another circuit.
when i made a circuit i will take more o-scope pics.
Adam Manick PKM4 years ago
That is not battery powered. You plug it in. And yes you can get nice arcs from this circuit with a little improvement.
NcssR4 years ago
hey guys,at this joule thief works a c945 or bd 139 or sdt9208 power transistors
Mudbud4 years ago
I can not find a 512ohm resistor anywhere! what else can I subsitute?

P.S no Im not going to get one online, I'm not old enough. :)
sdobbie4 years ago
Would an n channel enhancement mosfet work instead of the transistor. I have a p60nfo6 mosfet and a k3567 mosfet.
I used a 100 volt 3 amp mosfet, had to change resister to 33 ohms and a 9 volt battery. the battery life is short pulling one amp.
andy5 years ago
I have followed the instructable and found the voltage I'm getting to be a lot lower. I got the circuit resonating at about 24ohms on the resistor, but I always seem to require a capacitor between the Hv outs. The highest voltage I got was 30v out, changing resistor values decreased voltage significantly +/- 10ohms dropped to about 15v and further than that pretty much nothing. Changing capacitor values changed frequency but voltage was effected lesser than by the resistor (+/- 5 volts at the most) 33uF seemed to be giving the best result, any less and the oscillator wouldn't fire. Toroid was 100 turns against 10 tapped in the middle (5/5). The torioid is almost exactly the size of 2 stacked pound coins, 10/12ths of an inch across and 4/12ths of an inch deep. Curiously using a 1.5 volt source (as opposed to three) only dropped the hv out by 5v to (25 volts out). Also the wire I am using is significantly thicker than that shown, at 30SWG (0.315mm). Does anyone have any idea's what could be happening? Would increasing my Hv voltage (by three times) just require (3 times) more turns on the Hv coil, or is it more complex than this? Any help/explainations appreciated, Thanks
rayfalcon andy4 years ago
try to use a 2200 uF in your project and see how many am/ volts you get then However DO NOT get into the path of it trust me i have done it, my parents picked me up off of the floor.
andy rayfalcon4 years ago
Capacitors on the output severely reduce the output voltage for me. I think it's because the toroids are from an old (PC) power supply. I think what is happening is that there is a limit to the speed at which the toroid allows the circuit to oscillate, in effect capping the maximum value. A torrid a friend gave me a long time ago is not limited by this effect, and produces upwards of 100 volts however it requires a very high turn ratio, roughly 3tap3 to 300 turns. Even in this case the capacitor ruins the resonance and drops the output to around 20/30 volts. I suspect the issue is the type of toroid core (powder/solid etc).

I know what you mean about the high voltage, I once accidentally shorted a camera flash capacitor with my fingers, it was like being punched in the arm, and left a nasty little path of dead skin into my finger. I have been very cautious of high voltage since then.

I have never had good efficiency with this circuit, even the successful coil burns 60 to 70% of it's power depending on source current and voltage. Having said that it could drive a "low" voltage (fires at ~110v, stays partially lit right down to 70v ) Nixie tube for a couple of days on an 1000mAh 1.5 volt cell, which was fairly impressive. Currently I am looking into more efficient circuits. A 555 timer based version seems promising.

rayfalcon4 years ago
what? No high voltage warning lmao little bit too late to worry about it now, after i already got the chit knocked outta me.....I had to test it to see if it was actually "high" voltage ( not really) but i accidently got into it while adding finishing touches to mine ( i forgot to take my battery out ) You need your warning up there so no one can say hey you didnt tell me and such and such got hurt ;-)
Great instructable 10 + rating and 5 stars
mattccc6 years ago
will someone try to make a florscent tube driver with this
OK I am actually going to try that. The only difference is that I am using a 120 volt to 12 volt step down transformer.
omnibot mattccc5 years ago
12V (author)  mattccc6 years ago
i might if i can find some bigger parts.
gizander5 years ago
I have a bunch of 0.5mm wire left over from a previous project...will it work instead of the 0.2-0.4? thanks...
Yes. but it may have a different effect than this project is intended to have.
Can we use a 6-0-6 :240 transformer instead of the toroid windings
Yes, you probably can. I used a 120 volt to 12 volt step down transformer, so im sure it will work.
joinaqd5 years ago
hey can i make an electric shocker out of this?(like "Plasmana's Worlds Smallest Shocker!" ?)Can i get shocked if i touch HV wires? 
I think it would be the World's Smallest Electrocution device. You'd probably die if you touched them; voltage won't matter but current will. Anything above about .05 Amps or 50 milliamps of current will kill a normal human being.
you mean 5 mA, (not 50 mA)
phephq joinaqd5 years ago
not usually. ive been shocked about 5 times by 120v AC current, and that usually can give out 20 amps before the circuit breaker kicks in. Either it takes more time, or the path needs to pass through your brain or heart. I've also been shocked by a large inductor (used as a transformer in a desk fan) when attaching it to a battery I know that 50v can produce a shock sensation, so I'm pretty confident that this could work as a shocker. To be safe though, ~~don't try it~~. who knows, being shocked all those times could explain a few things about me... To be less safe, I'd use it to charge a photo-flash capacitor, which only holds a small amount of current.
12V (author) 5 years ago
it barely produces 1ma! it does not hurt if you touch it but the neon extinguishes.
joinaqd5 years ago
 lol thanks for fixing the schematic...what does the feedback wires do anyway?
Last night I made three (almost) normal joule thief's and put them in cool gadgets, now I found this and would like to make it, but I was wondering about a few things first.
Is this thing dangerous, like a TC or is it fairly safe, like a Van de graff generator (I made a large one, there tons of fun :-)), because it is so low current that it would just give you a harmless little zap.
Thanks a lot,
A G33K

Shagglepuff5 years ago
Awesome idea! But I have two questions: 1)If you use a 9v battery, will each turn add 9 volts or something? 2)If you hook up another high voltage joule thief to the output of this, can you multiply the first joule thief's output voltage too?
1) I don't think that varying the input voltage will have such a straight forward effect on the output, I found that moving from a new 1.5 volt cell to a couple running at about double that (increase of 1.5 volts) increased the output by 5 volts, but my circuit is isn't behaving as described in the instructable (please see my other comment for details).

I think that the Hv output is incredibly noisy, even with smoothing caps I could imagine the resultant output (from doubling up) would varying wildly.It may be *possible* but there are going to be much easier ways of doing it. More windings on the Hv coil for example, or a different circuit.

Hope this helps,
joinaqd5 years ago
hey dude you wired them differently in the pictures than in your schematic. In the schematic, the centertap is connected to the base of transistor, but in the picture the centertap is positive...so which one is CORRECT?!?!!!
12V (author)  joinaqd5 years ago
i need to change the diagram
i have only just noticed
ct = +2.4v
thanks for telling me!
joinaqd5 years ago
be sure to use different colored wires next time im maaan confused
BOOM56016 years ago
Would 2 1kohm resistors in parallel work instead of the 512 ohm?
Yes, good luck :)
mattccc6 years ago
can i do this with a ferrite rod
Biotele6 years ago
I am curious if neon are as efficient as LEDs. How long do they glow for?
12V (author)  Biotele6 years ago
i haven't tested it yet also what type of batteries?
Biotele 12V6 years ago
compare LEDs to neon with the same type of battery.