Picture of Make a SUPER Joule Thief Light!
A joule thief is a simple circuit that can take 1.5 volts and put out as much as 5 volts. It can light an LED super bright! But have you ever heard about getting 120 volts out of a AA battery? The Super Joule Thief can do just that! It is perfect for lighting lights during power outages or just for a desk lamp. It can even charge cameras and cell phones! Watch the video for an overview.

I entered this instructable into the Make it Glow contest, so if you like it, please vote for me!! 
Remove these adsRemove these ads by Signing Up

Step 1: The Parts

Picture of The Parts
This circuit requires very few parts:
-TIP31 transistor [HAS to be a TIP31 because it works the BEST :) ]
-10k POT
-0.1uf-1uf capacitor (I used a .22uf)
-Ferrite toroid or rod
-20 to 30 feet of 30 gauge magnet wire
-3 feet of 22 gauge magnet wire
-heatsink? (Do you want to power it with more than 1.5 volts?)
-AA battery and holder
-AC output adapter (A 2 prong to 3 prong adapter works great)

Scissors, solder, and other tools will also help.

Step 2: The Circuit

Picture of The Circuit
UPDATE!! I changed the .22uf capacitor to a .68uf capacitor and I am getting a higher and more stable output.                                                                                                                                                                                                         Here is the circuit. As you can see, the transistor acts as an oscillator and pulses the current into the primary coil. This induces a large voltage into the secondary coil. The two prongs of the AC adapter can be connected to the ends of the secondary coil, or you can solder the ends to a light bulb directly. This setup has a 10 kilo-ohm potentiometer. This controls the current that flows to the base of the transistor. More current means a higher voltage in the secondary, and ultimately a brighter light.  The .22uf capacitor seemed to improve the output of my toroid, so I left it in. You may have to change the value depending on the resonant frequency of your toroid, or you can just omit it and the circuit will still work great. It is a very simple circuit as you can see.
1-40 of 105Next »
celalboz20 days ago

will this power a 110v cell phone charger, instead of just a light bulb?

thanks for kind reply in advence.

ggarcía-224 days ago
You said Using a TIP31 you can use a 4watt Transistor. What do I need to use a 9watt or 13watt led bulb. I've heard about using MOSFET, what do you suggest?
ggarcía-226 days ago
Hi men!!!

This is awsome, I'm thinking to use it with a solar cell or with a dynamo in the bike
ThorMan7 months ago

Hello my friend!

Can you sell me this?

If yes how much?

How is the wiring to the 2 prong adapter connected? And where is the small ring tab on the two prong adapter connected?

Thorofazgar10 months ago

how long will it run on the 1.5 volt battery ?

mihir.sahu.35511 months ago

can you make a step by step video of this.... can omit capacitor have any effect and can i wind toroid cuntinously

mihir.sahu.35511 months ago

can you make a step by step video of this.... can omit capacitor have any effect and can i wind toroid cuntinously

TK1756721 year ago

Rewound it in a ceramic encased toroid (out of an old CRT monitor) still just buzz but no high voltage. i AM getting output but it is very faint. so i guess i need to replace the transistor

mosfet* with transistor

The only NPN i have that is over a tiny logic transistor is a

FJAF6812 (lol i know i have 5v logic transistors then jump to 1500V)

Lighting up an LED (no resistor) off a 1A 12V power supply -_-

TK1756721 year ago

I built one using an IRF630 but i had to use 5-12 windings on the primary and so far i have about 80-90 on the secondary so i decided to test it. i applied 6 volts to it and get a very high pitch wine (that means it is working!) but i don't seem to get anything from the secondary. i have a small neon bulb and nothing happens. i even touched the 2 leads and still nothing.

clevelandstorms (author)  TK1756721 year ago
First off, I wouldnt use a mosfet because this circuit is not meant for a high current output. A normal bjt should be fine. The most likely problem is that the secondary is shorting to the ferrite core or the windings are arcing over. This has happened to me. I covered my toroid in enamel before I wound the coils.

I will attempt putting some tape on it and re-winding. :( and will the mosfet work? it is all i have that is over a tiny logic transistor
Also i seem to get a very tiny anount out of the secondary beacause i tried connecting a piezo speaker

Just did it with a flyback and it works fine (tiny arcs compared to my 555/2n3055) but that means my driver is fine so i am going to have to re-wind the secondary :(

Insulated and the same thing happens.

I'm starting to build this. How do you think 22 gauge wire would go with building this instead of 22 and 30? Would it increase or decrease voltage? Also, how would a 2N3904 transistor work instead? Would I need a beefier one or a smaller one if I can't use that one? Lastly, how would a 1uf capacitor work instead of a 0.68?

22 should work fine but that transistor is WAYY too tiny for this build :P as for the capacitor it has to be a film capacitor it can't be a small round one (electrolytic) since they have a positive and a negative.

When I searched film capacitor and looked onto images, it came up with those square capacitors (That's what I call them :P), however, it also came up with some square capacitors that are slightly rounded like those circular disk capacitors. That's the kind I have when I said a 1uf capacitor. I don't believe those have a positive and negative.

I just said film because that is what i call them :P but you can use any non polarized capacitor.

I personally am using a .47 uf "box" film capacitor rated for 300V (only one i have that is not electrolytic)

amueslim1 year ago

how about the transistor may i change to the other type....? please help me

clevelandstorms (author)  amueslim1 year ago
Yes you can. What type do you have?
AS671 year ago
is there a way to make a 13.4v version to jump start a car with a dead battery with (or similar) method?
PhilKE3FL AS671 year ago

When clevelandstorms says several amps he means around 650 cold cranking amps, meaning in cold temperatures. Car batteries are rated in Cold Cranking Starting Amps or CC: 650 CC or 700 CC for cold cranking amps.

Let's look at using an old standard 4 Watt 120 Volt night-light bulb. This bulb requires about 33 mA at 120 Volts. The circuit we make would still have to supply 4W but, from your 1.5V battery, which means about 2.67 AMPS of current. Which, to say the least, is requiring far more than we normally require from a single AA battery! The thing to remember is POWER, how many Watts does it take? P=I*E or in words, Power (Watts) = Current (Amps) times (*) Electromotive force (Volts) so 4W = I * 1.5V => 4W / 1.5 V = 2.67 Amps yet at 120 Volts 4W / 120V = 0.033 Amps or 33mA. This means to get the 33mA at 120Volts the 1.5 Volt battery (if supplying 1.5 volts) needs to supply about 2.67 Amps of current, and as the voltage drops the battery has to supply MORE current to produce the same power, Watts, to keep the bulb going.

Simply stated, to use this circuit to run an LED night light is, sort of, counter productive. Don't get me wrong, this is a wonderful demonstration of running a very small 120Volt device from a 1.5 Volt battery. But, if all we want is a night light, then using the standard Joule Thief circuit without that large coil (with its shock hazard) to simply run an ultra bright 3V LED directly would be far more efficient. You'll get about a week or more of operation from a dead (~ 1.2 Volt) AA battery instead of only 2.5 hours on a new AA battery for the 120Volt LED night light. It would be the same for charging a cell phone, if we could do it directly with a simple Joule Thief we'd get far more power transferred to the phone battery and far less power wasted just running the conversion circuits.

clevelandstorms (author)  AS671 year ago
Unfortunately not with this circuit. You need something that could supply several amps and this circuit will supply a few milliamps at most.
arghya91 year ago
i tried it many times,but it did not work. plz plz plz help me.

Note, the two shorter coils need to use the opposite ends of the wires: The starting end of one wire and the ending end of the second wire get tied together and they go to the + side of the battery. The diagram above makes it look like only one wire is going to the + side of the battery but it is actually two wires from the two short coils. I usually wind the two wires together then take the starting end of one & the ending end of the other, solder them together and that goes to the + side of the battery. Hope that helps, it is usually the easy mistake to make using the two ends which are together but this produces a non-inductance circuit and so won't work. Look at: to see how he shows which wire to use.

asdfrtyvbn1 year ago
hi!thank you for your nice project.can you tell more about output frequency and how can i change it?
dudes1 year ago
Awesome design
clevelandstorms (author)  dudes1 year ago

Thank you

infanati1 year ago
im a little confused with one part of your schematics
the arrow at the end of the base of the transistor connecting to the resistor. Is that supposed to be ground?
clevelandstorms (author)  infanati1 year ago
That's the variable resistor's wiper terminal
bneo991 year ago
About this :


It can't kill you, but it is quite uncomfortable.

Did you accidentally shocked yourself?
clevelandstorms (author)  bneo991 year ago
Yes and not accidentally! I had to see exactly what voltage was outputted and if it was enough to give a jolt. I'm basing a pen shocker on this idea
You're trying to make a pen shocker from this idea? Is it also a joule thief?
Has there been any improvement in the high pitch noise or any idea on how to inhibit it?
Coat the toroid in epoxy. Also, if you use a higher value capacitor, the noise will be less. This is not really a problem for most toroids.
This is a nice project and a well done instructable!

Just a cautionary note: I think that it's important to consider the type of load that you put on the output - I confess that I haven't built this yet myself, but I will say that (without looking at the output on a scope), you would want to be careful of the frequency, and the shape of the waveform when powering anything other than a resistive load. You could damage some devices if you're trying to power them with something other than 60 Hz in the U.S..
1-40 of 105Next »