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From: akcs.rick@vpnet.chi.il.us (fred salchli)
Newsgroups: sci.electronics
Subject: EVENT COUNTER
Keywords: counters,data aquisition
Message-ID: <26dd5749-39csci.electronics@vpnet.chi.il.us>
Date: 30 Aug 90 21:55:06 GMT
Lines: 24

I am a grad student working in neurophysiology, attempting to both
perform detailed data aquisition/analysis and streamline both as well. I
am currently researching mammalian circadian rhythms and am using
locomotor activity as an assay. Rodents are placed in cages with a
running wheel, the running wheel is coupled to a microswitch and the
signal is recorded on a strip chart recorder. This is not quantitative,
making statistical analysis difficult if not impossible, and also messy.
     
What I have been trying to do is build a computerized system. However, I
have not had much success building a circuit which will reliably latch
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. 

If anyone can help me with a design or a chip which can accurately
perform to my requirements I would be greatly indebted. Leafing through
application sheets has not yet yielded the right configuration, and if I
work my way through all of them I will get my PhD in 2025. Thanks!

P.S. I have thought about putting a delay in the aquisition software, but
in order to get the greatest revolution, I must sample at a rate of at
least 5Hz.