rniniver

In an AC application usually a TRIAC is used, in this case a DIAC into the
TRIAC control from an OPTO output will do the trick.   You have control dwon
to a zero crossing at 60Hz.  If you want to USE an SCR this will require phase
control
and opposing above and below rectified wall these require a signal to PIC on
+/-
peaks or Zero crossing if you a running asymmetricly.   In the SCR case a
direct drive "pulse" from a OPTO thru a resistor will fire the SCR into self
sustaining
conduction until a zero crossing occurs at which point the SCR has no
conduction path and will shutoff.   You can look up simple ideas in the
DIGIKEY catalog
that show some of these...

Eric Borcherding