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From: reynhout@wpi.wpi.edu (Andrew Reynhout)
Newsgroups: sci.electronics
Subject: A pathetically simple question...
Summary: time-delay circuit schematic request
Message-ID: <4377@wpi.wpi.edu>
Date: 29 Sep 89 14:47:51 GMT
References: <1989Sep28.122217.26867@watcsc.waterloo.edu>
Reply-To: reynhout@wpi.wpi.edu (Andrew Reynhout)
Distribution: sci.electronics
Organization: Worcester Polytechnic Institute, Worcester, MA. USA
Lines: 14


   Help!  This is an amusingly simple question, but I've been working on it
for some time now, and can't come up with an answer...

   I need a circuit that will, on application of power, cause a delay of 5-20
seconds before allowing current to flow through (a different part of the circuit)
   Basically, it should take, say, 12v, wait 10 seconds, then trip a relay.
It's for an alarm circuit.  (I didn't see much point in paying $159 for $30 of
components and a few hours of work.)
   I tried a deceptively complex setup with a FET and a timing cap and all sorts
of other nasty things, but I can't get ANYTHING out of it.

   Any help would be greatly appreciated...
   Andrew