Make a SUPER Joule Thief Light!

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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!! 

Step 1: 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)
-Perfboard
-Epoxy

Scissors, solder, and other tools will also help.

Step 2: 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.

Step 3: The Toroid Transformer

Let's take a minute to discuss the ferrite toroid. It does not have to be a toroid. If you open up a radio, you will find a ferrite rod inside that has a layer of wire on it. You can take off the wire and use that. Toroids take up less space and they also look nicer. There are several different kinds.

I used a black toroid from a 1983 television. Mine had a white plastic covering on it, so I popped it off. I found out that these toroids with the plastic covering are the best to use. If you would like to make a giant one, use a giant toroid. But the most common are one inch toroids.

They are also different colors. I have used yellow, black, and green, and these have all worked fine. But BEWARE! Some do not work as joule thiefs. It is best to make a normal joule thief and test if that works before doing all the work winding a secondary to find out that it does not resonate.

Step 4: Winding the Toroid Transformer

First, take some 22 gauge wire and wind 11-15 turns. Use a smaller amount for a smaller toroid, and a larger amount for a larger toroid. Cut the wire at the end of the 11-15 turns, leaving a few inches at the end. Scrape off the enamel coating on the ends of the wire. Next, take another piece of wire and twist it with one of the ends that you previously wound. Wind 4 more turns in the same direction. Cut the wire, leaving a couple inches at the end. Scrape off the enamel from the ends. Now you should have 3 connection points: a start, an end, and a center tap. The center tap is where you twisted the two wires together between the 11-15 turns and the 4 turns. This is your primary coil. 

It is a good idea to put a small amount or epoxy over your primary winding to keep it from sliding while you are winding the secondary.

Next, take some 30 gauge wire and start winding the secondary coil. You want to make one layer with the space remaining on the toroid. Then, start winding back over the layer you just wound. Keep doing this until you have around 200-300 turns. More turns = more voltage. I suggest that you wind 50 turns at a time, cut the wire, solder a new piece to it, and wind 50 more turns. This will keep the wire from knotting and breaking and will also let you take breaks without sacrificing coil output voltage. When you are finished, scrape the enamel from the two tips of the secondary and cover the whole toroid in a good layer of epoxy.

Step 5: Solder, Solder, Solder!

Now just put the circuit together based on the diagram!

Note what end of the primary connects to the collector, and what end goes to the potentiometer. The longer end will go to the collector.

If you want to get fancy and universal, connect the AC adapter to the secondary's output leads.

The toggle switch should go between the positive input and the center tap.

Step 6: Putting Everything Together

I epoxied everything onto a piece of perfboard. But feel free to get creative! If you wanted to, you could use a rechargeable AA battery and hook up a solar panel.

REMEMBER! THIS DEVICE OUTPUTS A HIGH VOLTAGE SO IF YOU TOUCH THE SECONDARY LEADS WHILE THE DEVICE IS ON, YOU WILL GET SHOCKED! 

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

Step 7: Using It!

Now find a light bulb less than 4 watts. LED bulbs work the best. I am using a 0.5 watt LED bulb and it lights up 2x brighter than it does in the wall. Plug it in and flick the switch! If you hear a faint high-pitch humming, it is just the transformer resonating. Use the potentiometer to dim the light if you want. The dimmer the light is, the longer the run time. The run time is about 2.5 hours with a fresh battery on full brightness.

You can use this ti charge cameras and phones too! But it is best used as a light.
If you have any questions, feel free to message me and I would be happy to help out.

Thanks for viewing my instructable and happy making!

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141 Discussions

(1) If I use 2@ 1.5v aa batteries (or 2@ 1.2 rechargeable) what will I need to change, if anything, for it to work.
(2) will I have to change any components if I use this with 2@3.7 lithium batteries in parallel to try and make the light last longer.
(3) what size diameter toroid did you use.
sorry if the answers are obvious to you and others but I am very new to this and intrigued by how much you have increased the voltage so much . Thank you

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ZEPHER 6

1 year ago

can i put 2N3055 transistor without putting the above one

1 reply
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ManoelG3ZEPHER 6

Reply 6 weeks ago

Probably yes, a 2n3055 would work, but it is bigger.

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eric.dahlgren.18

Question 9 months ago on Step 7

Would you be able to used this setup to power a very small electric car (one that is normally powered by a AA battery)

1 more answer
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ManoelG3eric.dahlgren.18

Answer 6 weeks ago

If the very small electric car is normally powered by an AA battery, you can run it with the AA battery, it doesnt need this circuit.

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f.dufourg

4 years ago on Introduction

36W is 36W if a 120V power supply gives 36W of cource this is 0.3A of current.
On this circuit, the power source is the 1.5V battery. If you take 36W from a 1.5V source this is 24A as the circuit in not 100% efficient, there is power lost in the inductor, the transistor, ... so I estimate the current the battery should deliver is around 30A.

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ManoelG3f.dufourg

Reply 6 weeks ago

Therefore there is an error in those numbers, because a 1.5 V battery would never ever deliver 30A.

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PierreV16

Question 9 months ago

Center goes to the + 1, 5V. The bottom goes to the bottom of the pot, the left to B by TIP31. As yet I understand it.
My problem is the upper red (which says 350 t) and the right red (which says 200V) should also contact somewhere with it. Can You clarify something please, here I coming not out.

5 more answers
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clevelandstormsPierreV16

Reply 9 months ago

Neither end of the 350t coil is connected to the base of the transistor. If this was a slayer exciter then there would be a connection. However in this joule thief the 350t coil is free standing

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PierreV16clevelandstorms

Reply 9 months ago

If the 350t is free standing is, from where it gets than current to give 200V out?

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preschauPierreV16

Reply 6 weeks ago

The ferrite core and its windings is a transformer, the energy is "transformed" from the primary winding to the secondary winding by the varying magnetic field induced by the current in the primary winding.

No electical conection is needed.

Google: "Transformers".

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PierreV16PierreV16

Reply 9 months ago

or do you mean that the line 3507 is connected to the B of TIP31

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tjh20

1 year ago

Can this circuit be modified to power a larger LED? For instance a dimmable A19 size bulb, rated to use 9W@100mA maximum on line voltage (120VAC).

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DamithaN

1 year ago

Will it work if, a capacitor of 10f(with 2.7v rating) is used instead of 0.22uf capacitor that you have used in this project?

2017-07-15 20.18.31.jpg
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ggarcía-2

1 year ago

I found two new MOSFET IRFZ44 would it be posible to make it work as oscillator?

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ggarcía-2

1 year ago

Of course, Also I have my tiny 2n2222 as Oscillator, but this time I connected a ceramic capacitor labeled "224" between Collector and emitter, and the LED is bright constantly!!

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AS67

4 years ago on Introduction

is there a way to make a 13.4v version to jump start a car with a dead battery with (or similar) method?

1 reply
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clevelandstormsAS67

Reply 4 years ago on Introduction

Unfortunately not with this circuit. You need something that could supply several amps and this circuit will supply a few milliamps at most.