Traffic indicator works from 12V or 24V

摘要

This circuit is a lot more complicated than the conventional thermo-mechanical switch unit used in cars but has been included to show the amount of logic required to provide the same function.Three optical interrupters are operated by a slotted disc attached to the steering wheel.When blocked,their collectors are held high by the 10k OMEGA resistors and because the outputs of IC5a & IC5d are normally high,the inputs to the gates of IC6a,IC6b,IC6c & IC6d are high,so that their outputs are low.The outputs of IC4b & IC4c are also low;hence the output of IC3c is low.