Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!rutgers!cmcl2!ccnysci!sukenick
From: sukenick@ccnysci.UUCP (SYG)
Newsgroups: sci.electronics
Subject: Re: How could I make a delayed one-shot?
Keywords: delayed, one-shot, simple, chips
Message-ID: <2603@ccnysci.UUCP>
Date: 12 Aug 89 14:52:54 GMT
References: <4689@merlin.usc.edu>
Reply-To: sukenick@ccnysci.UUCP (SYG)
Distribution: na
Organization: City College Of New York
Lines: 14

>use to make a delayed one-shot like this :
>[12 volt pulse that triggers on falling edge: 1st one shot .1 to 1 sec;
> then activates 2nd shot for .5 sec]
>(Note : when the one-shot generates its pulse, the input to the delay circuit
>	will go from low back up to high.  The one-shot pulses a solenoid, the
>	input is from a microswitch )

why not.....take the 12v pulse throgh a resistor to a 5 v zener;
then into a 74LS221 (or 74ls123) dual monostables (and the output
to a transistor to drive the solenoid). You've got one chip
with both timing elements, you can select the type
of edge triggered response (falling or rising)(one has a schmitt trigger
very stable timing without some of the flakeyness of using the
555 as a one shot.