At 04:11 PM 30/08/2012, you wrote: >On 31 August 2012 05:02, Paul Anderson wrote: > > There are 110 volt LED bulb replacements, but they are pretty expensive= .. > >One could easily enough [tm] build an LED driving from mains supply >that provided power to a reservoir capacitor when Vmains is under say >10V near the zero crossing points. There are power supply ICs that do >that, but it should be possible to do a minimalist version with 2 >transistors * and a few Rs Cs and Ds. * - A FET as main pass element >as bipolar as gate clamp maybe. FET gate is whispered on by mains but >clamped off by bipolar when mains is above target max. feed with 1/2 >wave or full wave as desired. > >May need a bit more glue to ensure it ALWAYS fails FET off when there >is any doubt :-). There is no doubt in my mind that it would always fail off-- just in some cases there may be a bit more smoke than others. --sp =20 --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .