On Fri, 11 May 2007 13:57:59 +0000 (UTC), you wrote: >M. Adam Davis gmail.com> writes: > >> On 5/10/07, Peter P. yahoo.com> wrote: >> > To sense high and low loads I have used two antiparallel diodes before. >> >> This is a great idea. Just put two diodes antiparallel to each other >> in series with the load. There will be no voltage across them when >> there is no current drawn. Any amount of current draw will place a >> 1.5v AC square wave across them. Make sure they can take the load. > >Actually you want to use diodes with low drop, i.e. Schottky, and you can, >because they do not need to withstand line voltage. Then by the time 2-3A are >drawn (250-350W in 110V land) they need cooling. The 0.1uF cap across them >removes switching noise and there will be a relatively nice square wave voltage >on them (about 0.8-1.2Vpp). This is not enough to light a LED but something >creative can be built from this starting point. As it's AC, a simple capacitive charge pump would give enough voltage to drive a LED or optoisolator. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist