michael brown wrote: > Don't get me wrong, I am intrigued by the idea of using a switching > supply for the rest of the circuit. Just out of curiosity, I worked out the numbers for a simple buck regulator that would convert 50V at 10uA to 5V at 100uA, just to see if it is doable. I chose a switching frequency of 100 kHz for a good balance between being easy to filter out of the audio and good efficiency. I came up with a coil value of 100mH, which is rather large. In fact, I couldn't find any 100mH coils that didn't have a self-resonant frequency that was less than 100kHz! Any ideas, or is this a lost cause? Is it possible to build a resonant converter that can work with nonideal coils with good efficiency? It sounds like things could get very complicated very quickly. -- Dave Tweed -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu