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.
>



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