I noticed those cheap novelty shake lights are getting dirt cheap on ebay and im wondering if it would be possible to use the boost circuitry of this light to drive a luxeon. Anyone know how the circuitry design works?
AFAIK, it doesn't use a boost circuit. Depending on the make/brand, it uses either a capacitor, rechargeable Li-Ion or NiCD/NiMH. Some cheap brands makes use watch batteries to drive the LED close to full brightness in order for them to sell...
What legtu didn't add is that the lights don't recharge. Once the watch battery runs out, the light is no longer functional. The magnets in them are not powerful enough to recharge, even if it had a rechargeable battery or capacitor. You get what you pay for!