The problem is that I'm trying to fix a circuit that's already been 
committed to PCB with the least ugly kludge possible.  It's like the Apollo 
13 problem: trying to turn what you have into what you need.  What I have is 
a 555 one-shot and an extra NPN transistor. What I need is a retriggerable 
one-shot whose output goes high and stays high when the input receives 
negative-going pulses, then goes low again once the pulses have been gone 
for a second or two.  I'm looking at the inner workings of the 555 to try to 
come up with a clever way to do this, but I'm running out of cleverness.  I 
don't have access printed resources at the moment, and my Googling has yet 
to expose a solution.  I'd be very grateful if anyone who has come across a 
circuit that fits this description could pass it along.

RR



> I'd do it with a PIC10F20X. It would be 1/10 size, cost 1/5 as much, and
> would be more reliable than a 555. Take about 5 minutes to write this 
> code.
>
> --Bob


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