Byron A Jeff wrote:
>
...........
> Enter AppNote 521 "Interfacing to AC Power Lines". Conceptually it's simple
> but I have to ask the dumb question: What's the return on the AC line? ......

Byron:

The idea in AN521 is to use the clamping action of the input protection
diodes
to turn the 115 VAC mains voltage into a square wave.  The app note
shows a
5 meg resistor between the hot (black wire in US) and the input pin.  I
think
your question is what to do with the white neutral wire.  I think the
answer
is to put a 5 meg ohm resistor in series with it to the PIC ground.
This way
you are not concerned about improper house wiring.

On a similar note, when the origional fuzz busters came out the
manufacturer
gave instructions for the truckers to connect one wire to ground and the
other to a hot wire(no polarity needed).  This worked because they used
a full wave bridge rectifier in the DC powered fuzzbuster.

Have Fun,
Brooke