Make has a great weekend project that shows you how to make a Joule Thief, this is a device that allows you to run an LED from a single 1.5 volt battery. For a similar project check out the rusty nail LED project.
Via: Make
Other than the toroid coil here is everything that you would need:
1K Resistor
NPN Transistor
Blue LED or White LED
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This is a really cool circuit. The ones I’ve made have ran for days on a “dead” batteries.
Andy sells a kit at his site for a buck: http://www.solarbug.com/solar-kit.html
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I’ve seen circuits similar to this, it works my the transistor causing the transformer to oscilate
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This just gave me an idea for a circuit: A “reusable” joule thief. Such as the joule thief either is used to recharge another battery, or stores the remaining power in a large capacitor for later use.
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How about a MOSFET-based circuit- less loss, right?
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Very interesting and helpful post.
I add your blog in my Google Reader! 😉