Joule Thief Flashlight.

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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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    26 Comments

    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.

    2 replies

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

    http://www.evilmadscientist.com/article.php/joulethief

    or here if you cant find one

    forgot to add link

    http://www.pablomontanez.com/littleupdates/2012/01/12/joule-thief-no-toroid-no-coil/

    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?

    1 reply

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

    Excellent! Always happy to inspire.

    SInce you talk about DT I presume your are UK based? If yes then Rapid Electronics (beloved supplier to most DT departments) sell a AA switched box with a small slide switch included just like the one you have used. It's probably available eleswhere too.

    Great project, I'll be trialling it soon, I've got a jar full of ex-digital camera AA's.

    What is "DT" exactly? Although I am puzzled now, I bet the minute you say it, i will smack my forehead and say: "Duhhhh."

    You should have read my new instructable! Haha. No injuries or chipped razors,

    It's a standard Radio Shack 2 AA lidded battery case. It actually was the perfect size.

    Nice packaging and way to show actual implementation. The hot glue really helps those freeform circuits survive actual pocket conditions and serves to help waterproof in some instances. I was slightly disappointed it was a slideshow. They aren't available in pdf format and I think your work is good enough to refer back to later. Even so, as long as the internet stays up, it is available.

    1 reply

    Thanks! Although, I believe an -ible is for an original idea, while a slide show is a fair expression of an inspired idea. This is by far the most rugged flashlight I have made, by the way. Very drop proof and functionally sound.

    Idea good. Instruction minimal at best. Try to put more effort into this. Disappointing.

    3 replies

    not everything at Instructables HAS TO BE an Instructable. try to put more effort into your comments. Disappointing.

    I disagree with you. When there are a bunch of pictures with no instructions on a website branded specifically to "instructables", then it becomes a image forum. Go post on Flickr if you have no instructions.

    I'm very sorry to all. Mrsplooge -you have a very valid point Berserk87 and hominid - I will improve the comments, just for you. I will also try to add more instruction. I didn't go into detail because it has been done, many times in fact. I actually did it precisely from another -ible.