On 2/22/07, Jinx wrote: > > > I am looking for suggestions on the cheapest way to build a circuit > > that will sound an alarm if current is being drawn in a 110VAC circuit. > > I want it to be cheap, cheap and be powered by the 110VAC. > > A transformerless supply, a PIC with a comparator (or a plain PIC > and FET might probably work) and a Hall Effect sensor, or some sort > of detector coil, if you want to sense the current from outside the wire. > It'll be cheap-ish but maybe not cheap cheap. There was a thread a > long time ago about someone wanting to detect when the washer- > dryer was on (I think the above was the solution), and [EE] Appliance > Current Sensor from August 2005 Much, much easy and of course without any PIC: search for a REED contact (it's a gold plated contact in a compact glass case, with a gas inside). Turn arround the glass a wire about 20-30 times. The number of turns and the wire diameter will gave you the realay sensing current. Voilla you have a homebrew current relay. Use the contact as you wish to bleep-bloop or whatever. Vasile -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist