On Wed, 10 Mar 1999 09:34:45 +1100, Tony Nixon wrote:

>
>You may need to isolate the SCR from the PIC.
>

I just finished the first prototype of a unit that controls
a Cheston heater.  It's phase controled via 2 inverse
parallel SCR's which at peak run 350 amps at 480 VAC.  To
achive the proper isolation beetween the SCR's and the CPU
I had to use a gate trigger transformer.  The CPU sits on
the primary side and the SCR is on the secondary side
connected to the anode and the gate.  To fire the scr you
pulse the xformer.  This sends several large spikes into
the gate and turns on the SCR.  Be warned all gate xformers
are not created equal and you need to do a little research
to get right one for your SCR.  (Or at least in my case
they were)



--
Richard A. Smith                         Bitworks, Inc.
rsmith@bitworks.com               501.521.3908
Sr. Design Engineer        http://www.bitworks.com