Dear Jeff,

I developed a timer used to control the signal output one year ago. This
small timer system can be controlled both manually and electronically. The
basic idea of this timer development is to use a Monostable/Astable
Multivibrator (CD4047) to generate a basic clock frequency; and use several
Decade Counters/Dividers (CD4017) to get the timing accuracy you want. All
manual or electric control, and input or output of the timer can be built
up based on this basic structure of the timer. The cost (not include the
labor) should be within $400USD.

Also, it might be possible to use some kind of software package (LabView)
combining with other I/O device to realise the function you need if you
have these facilities. But, I have no experience of this approach.

This info is just for your reference. Please don't hesitate to contact me
if I could be of any further help.



At 10:29 6/10/00 -0500, you wrote:
>We are looking for simple digital timers/stopwatches that
>can be controlled electronically or manually. For example, an
>external electronic circuit with a manual switch or TTL signal should
>be able to stop and start the timer. We would also like to at some point
>be able to hook up photoelectonic switches. These timers will
>be used for reaction time and movement time studies as well as to
>double check some of our timing data we gather from our kinematic
>and kinetic instrumentation.
>The timer needs at least 1 ms precision and readouts. Layfayette
>Instruments has such devices, but they are expensive (about $600USD).
>It seems to me that less expensive devices are available. I am not
>against building a timer, as long as I can get the parts off the shelf
>(e.g. RadioShack) and have easy instructions.
>Anyone have any suggestions?
>Jeff Ives, Ph.D.
>Dept. of Exercise & Sport Sciences Phone: 607-274-1751
>Ithaca College Fax: 607-274-1943
>Ithaca, NY 14850 USA Email:
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PhD, MEng, BEng

School of Physiotherapy
Faculty of Health Sciences
La Trobe University
Bundoora, VIC 3082, AUSTRALIA

Tel: +61 3 9479 5771; FAX: +61 3 9479 5768

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