Joule Thief - Use LEDs With Only One AA Battery!





Introduction: Joule Thief - Use LEDs With Only One AA Battery!

About: Check out for some projects.

 Making LED devices portable can be a little bulky due to the batteries. The Joule Thief solves that, by boosting a single AA battery's voltage to a high enough level to light a LED.

This ible will entail how to solder a joule thief together from They cost $7 each.

The kit from thejoulethief is interesting in the fact that it deviates from the standard bulky joule thief design to a small and compact pcb layout with a few extra components for efficiency.

Step 1: Open Source

Attached are the Eagle schematic and board files. 

Step 2: Gather Parts

 Make sure you have all of the parts. Here is the listing:
 Qty 2. Transistor
2.2k resistor
Qty 2. 1k resistor
LED (your choice of color)
Qty 2. wire pieces

Step 3: Inductor

 I first chose to put in the inductor. The inductor looks like a fat resistor. There is a spot on the PCB labeled "L1" where the inductor should go. 

Insert the inductor, bend the leads so that it says put, and solder it in.

Step 4: Resistors

 Time for the resistors.
R1 is the 2.2k resistor (red red red).
R2 and R3 are the 1k resistors (brown black red)

Note that you should mount the resistors vertically to save space.

Insert, bend leads, and solder!

Step 5: Capacitor

 Grab the capacitor, insert in the spot labeled C1, bend and solder.

Step 6: Transistors

 The next step is kind of tricky. The transistor leads are normally in line, however to insert them in the PCB you will need to bend the leads into a triangle shape (see picture).

After bending the leads, carefully push down the transistor into the pcb until it seats nicely. Solder.

Step 7: LED

 The fun part! Put the LED in, make sure you note the orientation. The flat spot on the LED goes towards the flat spot on the silkscreen.

Step 8: Wire

 Here is the final step. Strip the wire ends, and solder it into the pads on the PCB.


Next it is time to test it out!

Step 9: Testing

The silkscreen marks which wire is positive and negative. Put the proper leads to any AA battery, dead or new, and see the LED light!

This is a great way to get compact LED lighting, using a minuscule circuit and one AA battery. The circuit operates off of "dead" AA batteries, making it a great way to reuse your old AAs. 

Pick up a kit at and have fun!



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    42 Discussions


    4 years ago

    I can't open eagle docs and I can't tell where to connect the input +/- or where the output+/- come from on the schematic provided. please help

    Just a question before building it: What can I do if I want higher output voltage? Which part(s) should I change?

    I'm not sure what program to use to open 2 Eagle schematic & board files. Can you please advise? Thanks Mark

    1 reply

    Now there is a new circuit out that uses only a tiny four legged IC, a tiny inductor, a battery and an LED. No toroids, transistors, resistors, etc are required with this "Joule Thief." Check out:
    A simple schematic is provided...

    Finally! A kit! I could never get the toroid version to work. Just got little flashes.... Anywho, Ill have to get one of these.

    3 replies

    I have wound Hundreds of torrois Jts hers one that will power a CFl blub or 500 christmas tree bulbs from just one 1.5 volt battery for 5 days straight !

    100lights from jt-christmas.jpgmy 110 volt jt-fusionchip-gadget.jpg

    I found a IC based boost regulator at Pololu that I liked. The circuit on this page uses 2N2222 which I haven't seen before. That will cause a loss in efficiency but should be a lot easier to find than the transistors of the classic Joule Thief.

    Again you are wrong . Joule Thief was coined by Big Clives . Also the circuit you posted does not run off a dead AA battery and requires +27 volts . This is a very old energy hog led blinker oscillator . DA

    Because this is not My schematic nor a joule thief . That was my point . I have no idea who this person is who posted this "joule thief project " but as i had said this is not a joule thief and yes it works but it is a boost converter thats all man . IF yo want to see real work visit overunity dot com and see the jule thief thread . thanks .

    Screw Wiki's there not the facts son . I am one of the inventors of the lowest powered light device in the world and have been very educated for over 40+ years in Electronics so i know .

    Unless you are 'Big Clive'  I don't think you have permission to call the the 'joule thief'.  Big Clive was the one who coined this name.  Before he called it the 'joule thief' he called it the 'vampire torch'.

    If you are Big Clive, thanks for designing such a nice kit!

    Otherwise, please don't take names from other people's projects.

    5 replies

    Sorry dude BIG clive didnt patent joule we all can make and use it...thatz why inventor like big .c publishes this invention in public

    It was patented In 2010 and the circuit described is not a Joule thief but a boost converted used in many solar garden lights . a REAL joule thief uses Ferrite bifialar transformer and ONE transistor and current draw is less than 1 milliamp on a silicon transistor of a volt of .725 . germanium Jt's can run as low as .2 volts and in the MICRO amp range while lighting up several Bright White Leds .

    Sorry I did not know, but the Joule Thief may have been coined by Big Clive, but it seems like Evil Mad Scientist popularized it (with no mention of Big Clive). 

    The EMSL does refer to Big Clive as "the original site"
    Clive credits "Z. Kaparnik" in EPE magazine.  I suspect the origin lies even further away...  I don't think that anyone has trademarked the name...

    This seems to be a different circuit, though (two transistors, single-winding inductor.)  Probably like or this one published (with lots of explanation) in Electronics Design

    Can anyone reach Big Clive's web site about the joule thief? It doesn't work for me.