On Thu, May 29, 2008 at 7:22 AM, slippyr4 wrote: > Hi All, > > I'm hoping someone can give me some help understanding this circuit- i'm > just a hobbyist with no training in electronics and i'm struggling with this > one. I think you're looking for something that isn't there.. This is a simple "trickle charger" which modern NIMH cells hate, and NICAD cells tolerate. The charger can overcharge if left on too long, which causes free oxygen and hydrogen inside the cell. The hydrogen escapes, and the oxygen combines with things. The resistor value is set to give a charge current that's roughly a tenth of the amp-hour capacity of the cells used. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist