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From: bame@hpfcbig.SDE.HP.COM (Paul Bame)
Newsgroups: sci.electronics
Subject: Re: Lap-Time Sensor for Autoracing
Message-ID: <6560010@hpfcbig.SDE.HP.COM>
Date: 13 Mar 91 19:47:10 GMT
References: <Mar.12.13.31.59.1991.9950@caip.rutgers.edu>
Organization: HP SESD, Fort Collins, CO
Lines: 10

Since the RC track is hostile to RF and audio, how about using (again)
light.  Place an IR LED on the car modulated at 40KHz and arrange one
of those IR receivers so it can only "see" the car after it passes the
point of interest.  You probably don't have to worry about the 20mA or
so the LED will require compared to the 10A draw from the motor.  You
will have to worry some about clean power to the LED/Oscillator if you
run from the same battery powering the car.

			-Paul Bame
			bame@fc.sde.hp.com	N0KCL