I agree with your observation about the need for a resistive load. I'm having difficulty getting my head around how the control circuit (some type of CPU) controls the load. so in series: live_in --- control --- live_out --- load --- neutral i think that control probably has to have a triac that it is phasing on and off in order to dimm/turn on/off the load. at the same time it's got to use that same line to power itself. i can't get my head around that part. i think i'll do some searching for how dimmers power themselves from the live line. hopefully one of them has a CPU in them so then it'll all be clear to me. thanks, roines William Chops Westfield wrote: On Wednesday, May 26, 2004, at 18:39 US/Pacific, roines reenig wrote: > I think we have drifted a little bit from what I attempted to describe > initially. I was wondering about that. You were mostly interested in how to get power at (for instance) a lightswitch, when you only have access to the "hot" side of the connection, and the load, right? Most things that do this (ie X10 dimmer switches, or regular dimmers, for that matter) rely on the load being essentially a slightly resistive path to the return (a 100W lightbulb has a resistance of only 130 ohms or so, so it's pretty easy to get 50mA worth of 5V out of there somehow. That's why they "only" work on resistive loads. Sneaky, eh? BillW -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics --------------------------------- Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics