Joule Thief Flashlight.





Introduction: Joule Thief Flashlight.

It's not the first, nor the last. but this was made almost completely from parts that were lying around.

I only bought the transistor and the case.

Toroid - computer motherboard
Toroid wrappings - Computer ribbon cable
LEDs - I have a jelly jar collection :)
Resistor, 100 ohm - left-over from previous project
Switch - Computer power switch

I credit all technological plans to 1up's "how to make a joule thief" instructable.

First, I took the standard radio shack dual AA case and removed the (-) teminal and the back plate. I stuck the terminal where the plate went and hot glued it in place. Next I wound the toriod, soldered the LEDs together in parallel, soldered everything together, and fitted it into the case in the other AA battery slot. By cutting holes in the case with my dremel the LEDs and the switch poke out nicely. After it all fit in, I sealed it all in place with plenty of hot glue. The glue keeps it all from moving and shorting.

Unfortnately, the switch has no latch mechanism, so the switch must be held down the entire time light is needed.



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    Whats the case that ur suing

    Please anyone help me. I cannot find anywhere how I can make joule thief flashlight with 3.7V cellphone battery or laptop battery. Everywhere people use 1.5V battery. What is the sheme for 3.7V. I have made a flashlight with 5 leds and 3.7V nokia cellphone battery, but it last for ~10 hours. After the voltage drops around 3V it gets dimm. So,..any ideas about the .....toriod....resistor value? Thanks in advance.

    Simple yet effective small flashlight, the joule thief is truly an impressive circuit! The case you chose is also very sleek and low-profile. :)

    That said, I would build this... but I don't have any Toroids laying around :/
    Oh well, Perhaps another time.

    if you have old power suply for computer you can get a feright bead go to this site its one that is pritty simple

    or here if you cant find one

    forgot to add link

    very neat design i like it,mine use 2 white led's and one red led in the back lol :)

    how much would you charge to make me one with an on/off switch that i can leave on?

    Probably very close to the cost of one with a momentary switch.

    Great instructable! I built one!


    Excellent! Always happy to inspire.