Path: utzoo!attcan!uunet!portal!cup.portal.com!mmm
From: mmm@cup.portal.com (Mark Robert Thorson)
Newsgroups: sci.electronics
Subject: Car Detectors for Traffic Lights
Message-ID: <18811@cup.portal.com>
Date: 26 May 89 01:29:14 GMT
Organization: The Portal System (TM)
Lines: 4

Does anybody know how the car detectors for traffic lights work?  Are
they tuned circuits?  If so, what frequency?

More importantly, can they be activated from a distance?