The joule thief is a clever little circuit that is fairly widespread on the internet. It’s name is coined from the fact that it is capable of ‘sucking out’ the last dregs of energy from supposedly ‘flat’ AA cells removed from domestic gadgets. It is a self-oscillating up-convertor and the higher voltage it produces can drive an LED to good brightness. I have designed a compact pcb that fits in one half of a 2-AA switched cell holder. If you use a new AA cell the brightness available makes it a very popular and actually useful project. As to final packaging and applications, well the sky is the limit. Here on this page are some examples but brand name, (remember the ‘Duracell Durabeam) case colour, packaging, green promotions etc, that’s up to you. Build-able by beginners in about an hour.
A few ways of building the PCB into a finished product. The switched AA battery box can
provide a wide range of outcomes whist solving many packaging issues….
The neat little stainless steel reflector came from IKEA – £2 of 4, highly polished inside!
Tiny little surface mount version, with a slide on/off switch, all mounted on the back of a single AA cell holder.
Photos below include this unit with a ping-pong ball on the LED as a diffuser. Lots of light for a hallway…
UV LEDS also provide some additional interests – ‘secret’ notes using a UV ID pen perhaps or Highlighter ‘ART’?