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7 comments

Jul 22, 2009. 9:11 PMvaak says:

It's a nice effort, but I think you need to understand the Joule Thief circuit better: - The wiring for the transistor can only work for U.S. (2Nxxxx type) transistors. European and Japanese transistors have a different pin-out and will not work as you have it. - The LEDs should be wired in parallel to maximize the coil's output. - The switches will not turn off the JT circuit, so it will continue to run (and waste electricity). Also, if your coil is properly made, you will get about 40 volts from it, which will probably burn out your transistor. - There is no need to fill the toroid with so many turns of wire - you may find that with 10 or 12 turn, the lights would be even brighter.

Aug 9, 2010. 8:49 AMVick Jr says:

Is there a formula for calculating the number of coils to use, given the properties of the transistor, toroid, etc.?

Dec 11, 2010. 9:45 AMacmefixer says:

Yes, but the joule thief is extremely tolerant of the inductance, and you should be more concerned about minimizing the resistance of the primary or main winding of the coil. Use heavier wire for the primary, and keep the number of turns reasonable, usually 20 turns is a good compromise between resistance and inductance. My favorite toroid core is the Fair-Rite 2673002402 (called a emi shield bead) from Mouser.com. It's a nice size, about 3/8"or 9mm O.D. See my blog for more info.

Nov 2, 2009. 4:34 AMbahi says:

Nice work thank you

Jul 21, 2009. 10:06 AM

iectyx3c says:

Excellent Captain Molo. You've got my vote for the pocket sized contest. Way to go!

Jul 19, 2009. 9:59 PMtoaignika says:

Very nice! I will be defiantly be getting around to this on (if I remember). A couple of questions though, does it have an on/off switch? Sorry if I missed something, and also, would there be a way to implement a flip switch to switch between the flashlight and the lamp?