Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!gem.mps.ohio-state.edu!ginosko!uunet!zephyr.ens.tek.com!tekcrl!tekgvs!arnief From: arnief@tekgvs.LABS.TEK.COM (Arnie Frisch) Newsgroups: sci.electronics Subject: Re: A pathetically simple question... Message-ID: <6027@tekgvs.LABS.TEK.COM> Date: 29 Sep 89 20:40:35 GMT References: <1989Sep28.122217.26867@watcsc.waterloo.edu> <4377@wpi.wpi.edu> Reply-To: arnief@tekgvs.LABS.TEK.COM (Arnie Frisch) Distribution: sci.electronics Organization: Tektronix, Inc., Beaverton, OR. Lines: 15 To build a reproducible time delay of several seconds to a minute - or more - a good approach is to do it digitally using CMOS. Build an inverter based oscillator out of two resistors a capacitor and two inverter sections (any good CMOS application manual will show how). Follow this with a multi-stage counter. The counter will have to be reset at power on - This will take a diode, a capacitor and a resistor. Limiting yourself to 1 uf capacitors and 1 meg resistors and using a seven stage counter IC, you should be able to get delays up to 300 seconds. I don't do schematics for free! Arnold Frisch Tektronix Laboratories