🚀 go-pugleaf

>... Rodents are placed in cages with a
>running wheel, the running wheel is coupled to a microswitch...

>... 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.

What exactly are you trying to do?  If you're after a count of wheel
revolutions, I would suggest you try an optical solution.  The metal running
wheels with which I'm familiar have a single crosspiece on each side for
support.  By positioning a photodetector properly, one could simply count
optical occlusions and divide by two to get wheel revolutions.  Obviously,
it would be important to arrange the optical path so as to minimize
interference from non-wheel-related activities of the rodents.

It should not be difficult to interface this type of circuit to the printer
port of a PC and sample the input at a rate far in excess of 5 Hz, so that
latching would be unnecessary.  If your hardware configuration precludes
this, you might consider a microcontroller such as the 8749.  These are
quite inexpensive, entirely self-contained, and easily programmable.  The
8751 even includes a built-in serial port.

-----------------------------------------------------
Gordon S. Hlavenka            cgordon@vpnet.chi.il.us
Disclaimer:                Yeah, I said it.  So what?