Steve,
We designed our own beam emitters and track sensors to meet the specs of
the high speed drag racing circuit. The response time is set to allow a
light rain or loose airborne track dirt to enter the beam and not false
trigger the sensors.
We manufacture our own since many sensor manufacturers generally do not
have specs on their sensor of this type unless their products are used in
some type of high speed application (either detecting very small objects or
very high speed 300+ MPH). We have measured many commercially available
products and found the repeatability was terrible, especially photocell
types and early IR components.
Total response time for the RACEAMERICA model 5140A Track Sensor receiving
a coded signal from a RACEAMERICA model 5040A Beam Emitter, (this is the
hardware shipped with our Timer AC4 Autocross timer) is 3 milliseconds with
a repeatability error of plus or minus 175 microseconds maximum. This
means if a car was crossing the finish line beam at 40 MPH, 2.1 inches of
the car enters the beam before the sensor triggers. Dirt or rain moving at
a speed of 9 MPH would need to be 1/2" wide to trigger the beam (pretty
good size rain drop!).
Side Note:
I must say, I'm impressed with the technical knowledge level and
familiarity with timing techniques of the autocrossers out there. Most
automotive racing groups we are involved with are very technical on their
cars with a basic understanding of timing used to measure their vehicles.
Dennis Laczny
RACEAMERICA Timing Systems
http://www.raceamerica.com
>Thanks. I understand what you are saying. What kind of timing heads to you
>folks sell and what is the variability in these.
>
>Thanks again,
>Steve
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