Thats what I have right now is a hall sensor and that feeds to a small gain stage. The issue is, for an AC waveform, that the output mimics the AC and rides on a 2.5V (half Vcc) offset. Its the matter of detecting when a very small current is flowing. Of course, now the issue is that someone else brought up...the new Cali laws that require SMALL current flows for wall warts (ie...switchers and not just cheap linear warts) the ability to detect them may be even more difficult. I've convinced my client that this may either have to change in his overall business plans or we may need something more mechanical rather than non-contact electronics. Its been one of these projects where it sounds so simple on the outset and grows in difficulty during the design stage. So, for now....I'm leaving in the Allegro hall sensor and op-amp and just see if I can function with that or just....leave that piece out. Its not the most critical part of the design. William Chops Westfield wrote: On May 14, 2007, at 7:50 AM, Alan B. Pearce wrote: >> duh.....Sensirion also makes those, > > Looking for alternatives before I commit to designing the LEM ones in. > Allegro micro has some hall-effect based current sensors that I believe are fully integrated: no fancy PCB design required: http://www.allegromicro.com/en/Products/Categories/Sensors/ currentsensor.asp -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist --------------------------------- Be a better Globetrotter. Get better travel answers from someone who knows. Yahoo! Answers - Check it out. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist