I've thought of that....but not sure how easy that would be to impliment into this particular design but I need to look a little deeper on it Mark Scoville wrote: I'm jumping in really, really late... sorry. Have you considered using something like a GFCI type of detector? If what you are after is an outlet that detects when current is being drawn I would think using a GFCI type circuit (Only 1 AC line thru the core, of course) might have some merit. As I said, late on this one, so if this is totally off the mark (or already been discussed) then just disregard. -- Mark > -----Original Message----- > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf > Of alan smith > Sent: Wednesday, May 16, 2007 8:12 AM > To: Microcontroller discussion list - Public. > Subject: Re: [EE] Detection of getting unplugged > > > 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. > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist --------------------------------- Give spam the boot. Take control with tough spam protection in the all-new Yahoo! Mail Beta. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist