Elapsed Timer

[lacofdbc]

I am looking for ideas to build or buy parts for an equistrian timer. The commercial units utilize a beam (infra red or laser?) that the horse breaks to initiate the timing sequence and then breaks the same beam to end the timing sequence. The elapsed time is then displayed (I am flexible on how this is to be displayed...) to hundreths of a second.<p>The commercial units are very pricy, and my electronics knowledge is very dated. So any help out there?<p>Enjoy reading the forum...<p>Eric

[MrAl]

Hi there,<p>Might be able to get away with just an ir diode
based beam, with ir detector diode/schmitt trigger
and have it turn a commercially purchased
timer on and off. Most of the work would
be simply constructing the ir diode array
(maybe 10 to 30 ir diodes) and the sensor.
You can use cmos switches to switch the timer
on and off (or push it's buttons electronically).
All of the parts are high speed, so i dont see
any problem with getting accuracy down to
100th's of a second.<p>Good luck with it,
Al

[russlk]

I have designed a timer that measures up to 9.99 seconds, how long a time do you need? You can check out the circuit at: http://www.geocities.com/russlk/circuits/pinewood.htm
You have to copy and paste the URL into the address bar, or geocities will not display the page.

[thomasng558]

If economy is a consideratrion, you may wish
to use ultrasonic range-sensors (A good choice is the Polaroid Kit, $50 from Wirz.com), and then
tie them into a stopwatch chip.