30 March 2015
Every Digital Electronics’ Lead The Way (see
sidebar) student has had to build a traffic light
controller for a lab assignment. Usually, they
are required to build a digital circuit using
discrete digital components. The student is
then required to use the digital circuit to
illuminate Light Emitting Diodes (LEDs) which
typically draw 20 milliamps. Some digital
circuits can provide this small current directly
without the use of drive transistors or relays.
More sophisticated students might make use
of an Arduino board to design an even better
circuit. The advantage of using an Arduino
board is that the design allows the use of
proximity sensors to detect the presence of a
vehicle in a turn lane, and have the Arduino
program change the timing of the lights
accordingly. The Arduino has input lines to
change the timing of all the light outputs.
Those who use an Arduino board for this
purpose can find many methods of
programming it on the Web.
A COST-EFFECTIVE
TRAFFIC LIGHT
CONTROLLER
By Alan Grambo
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