George wrote:

> That's what I suspected! I also had problems with a PIC=20
> (12C508) resetting when using that circuit, although I is
> suggested in a Microchip app note...
> Eventually I used a bc337 in between with a resistor to=20
> Vdd and the sense resistor onto the base with another res. to
> Vss from the base.
=20
=20
George,=20

I want to change the zero crossing detection circuit to what you have
suggested. Can you tell me whether the circuit shown below is =
functionally
similar what you have described?

                         +5V
   Live                   |
     o--                  |
   240V~              B | /C         =20
     o-------/\/\/---+--|             +-----------+=20
  Neutral    4.7M    |  | \E          |           |
                     |     -----+-----|    PIC    |
                     /  BC547   |     |           |
                 10K \   (NPN)  /     +-----------+
                     /          \ 10K
                     |          / (Pull down)
                     +----------+
                     |
                    Gnd       =20

Regards,                      =20
Bala

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