Is it perhaps simpler to use a small pic chip for this.
A 6 or 8 pin device with internal rc is ideal for a simple
task like this.

If this chip would cut power without incomming pulses
but the motor commands come from the main pic it
would still be safe (except a multiple failure in for
example a power supply failure in which all bets are off
anyway)

Peter van Hoof

----- Original Message ----
From: James Nick Sears lists@jamesnsears.com

Thanks for the ideas.  I was hoping for a one part solution, but a  
typical watchdog chip and an SR flip flop seems like a winner.

Have a good weekend all.
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