TRAFFIC_LIGHT_CONTROLLER

Published:2009/6/22 22:49:00 Author:Jessie | From:SeekIC

Oscillator U5A-B drives a 4017 divide-by-10 counter. The first output of U1 appears at pin 3, which supplies a positive voltage to U2, a MOO 3010 optocoupler/triac-driver IC, turning it and triac TR1 on. That lights I1, the red lamp. The second output appears at pin 2 and passes through D1 to the second MOC 3010, U3, thereby lighting the yellow lamp, I2. The third output at pin 4 turns on UJ4 and the green lamp, I3. The fourth output at pin 7 travels through D2 and into U3 to light the yellow lamp, I2, again.If you would like the traffic-light system to follow the normal sequence of green, yellow, and red, make the following circuit changes: Disconnect pins 10 and 15 of U1 from each other. Remove D1 and D2 and connect pin 2 of U1 to pin 1 of U3. Then connect pins 7 and pins 15 of UI together. Use U2 to drive I3 (the green light) and U4 for I1 (the red light).



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