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Article #2797Re: How much protection do I need?
From: Larrie Simon Carr
Date: Mon, 13 Apr 1992 05:54
Date: Mon, 13 Apr 1992 05:54
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In article <bc338569.82.703134685@longs.LANCE.ColoState.Edu> bc338569@longs.LANCE.ColoState.Edu (Brian J. Catlin) writes: >I am planning on building a digital tachometer for my truck. For the input, >I would like to count the number of times that the ignition coil is pulsed. >Since there are likely to be some rather large power spikes, I would like to >know what kind of circuitry I would need to protect my TTL-level circuitry. The best way would be NOT to connect your circuitry to the ignition coil, but to inductively couple (wrap a few turns around the main ignition coil lead). Clamp the output using zeners (collection of diodes) and run it into a inverter? I have seen designs where the input was a antenna that picked up the RFI from the ignition system. Doing this reduces the designs restrictions such a solidstate ignition compared to a old-fashions points system. -- Larrie Carr Engineering Science (604) 291-4451 Simon Fraser University (604) 298-1050 British Columbia, Canada larrie@sfu.ca
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Newsgroups: sci.electronics Path: arc1-ca.pugleaf.net!sparky!uunet!wupost!micro-heart-of-gold.mit.edu!uw-beaver!ubc-cs!newsserver.sfu.ca!larrie From: larrie@beaufort.sfu.ca (Larrie Simon Carr) Subject: Re: How much protection do I need? Message-ID: <1992Apr13.055439.21301@sfu.ca> Sender: news@sfu.ca Organization: Simon Fraser University, Burnaby, B.C., Canada References: <bc338569.82.703134685@longs.LANCE.ColoState.Edu> Date: Mon, 13 Apr 1992 05:54:39 GMT Lines: 21