Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!usc!henry.jpl.nasa.gov!elroy.jpl.nasa.gov!jato!jade!morris
From: morris@jade.jpl.nasa.gov (Mike Morris)
Newsgroups: sci.electronics
Subject: Re: A pathetically simple question...
Message-ID: <1833@jato.Jpl.Nasa.Gov>
Date: 30 Sep 89 07:07:12 GMT
References: <1989Sep28.122217.26867@watcsc.waterloo.edu> <4377@wpi.wpi.edu>
Sender: news@jato.Jpl.Nasa.Gov
Reply-To: morris@jade.Jpl.Nasa.Gov (Mike Morris)
Distribution: sci.electronics
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 31
In article <4377@wpi.wpi.edu> reynhout@wpi.wpi.edu (Andrew Reynhout) writes:
>
> 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.
Look in a catalog for an Amperite Delay Relay. They come in the same package
as the thermeonic high-voltage-depletion-mode-JFETs (a.k.a. Vacuum Tubes),
and are just a heater and a pair of bimetalic contacts. They come in
6v, 12v, 24v, 110v and 220v, and in times ffrom 1 second to 3 minutes,
normally open ort normally closed.
the part number format is obvious: