Path: utzoo!attcan!uunet!kitty!larry
From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.electronics
Subject: Re: Car Detectors for Traffic Lights
Summary: Having "fun" with IR...
Message-ID: <3205@kitty.UUCP>
Date: 2 Jun 89 01:33:45 GMT
References: <18811@cup.portal.com> <3185@kitty.uucp> <456@antares.uucp> <1741@ucsd.EDU>
Organization: Recognition Research Corp., Clarence, NY
Lines: 27

In article <1741@ucsd.EDU>, brian@ucsd.EDU (Brian Kantor) writes:
> As I recall, there were two frequencies sensed by the traffic light
> controller - one would simply extend the green and was for use by
> transit buses and such to save on gas and brakes, and the other
> caused immediate green in one direction and red elseways.  I don't
> remember the exact frequencies but they were slower than 20Hz, as
> I recall.
> 
> I'm told that's now illegal: "tampering" with a traffic signal.
> There's entirely too much law these days.

	Gee, it's too bad they don't have those kind of traffic lights in
the area of NY State where I live; I could have some fun. :-)

	I wonder if the traffic light optical sensors are sensitive to
IR, and would trip from some pulsed IR energy from a high-power diode
array?  This would certainly result in a rather unobtrusive, ahem,
"automotive accessory".  I tend to feel that any optical sensor of
this nature would respond to some really _decent_ IR energy, as
emitted from an injection laser diode.  However, a laser diode does
present some safety concerns, in addition to a directivity problem due
to lack of beam dispersion.

<>  Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp.
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