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From: corey@verdix.com (Corey Ashford)
Newsgroups: sci.electronics
Subject: Re: EVENT COUNTER
Keywords: counters,data aquisition
Message-ID: <753@verdix.verdix.com>
Date: 31 Aug 90 05:10:12 GMT
References: <26dd5749-39csci.electronics@vpnet.chi.il.us>
Sender: netnews@verdix.com
Reply-To: corey@verdix.com (Corey Ashford)
Organization: Verdix Western Operations; Aloha, OR
Lines: 32

In article <26dd5749-39csci.electronics@vpnet.chi.il.us>
akcs.rick@vpnet.chi.il.us (fred salchli) writes:
... some stuff ...
>when the animal runs. What I want is a circuit that will latch (I have
>tried various flip/flop configurations) until my I/O card reads it and
>then resets it. I have also tried an edge detection chip, but continue to
>have the same problem: If the switch is depressed the chip latches, but
>if the switch is not released immedietly, the chip records another wheel
>revolution when it finally is released. 

Sounds like the microswitch is bouncing when it opens.  A simple debounce
circuit like the following should help.

                     +5V
                      |
                      /10k
                      \
               /      /   |\ CMOS Schmitt trigger inverter 4584
      +------@/ @-----@---| >o-----------------------------------> out
      |               |   |/
      |   microsw     |
      |              ---
      |              --- 1 uF
      |               |
      |		      |
     Gnd             Gnd


The output will stay high as long as the switch is closed and will go
low about 10ms after the switch opens.

- Corey