Traffic light control unit - has counter operating into decoder with decade selection switches for period of operation selection

摘要

A traffic light control unit is based upon solid state devices and allows the periods of operation to be readily programmed. An oscillator input (1) is successively shaped (2) and divided down down (4) to provide a 1Hz input to a two decade counter (6). A decoded (8) provides outputs from three pairs (12, 13, 14) of decade selectors. AND gates (15, 16, 17, 18, 19, 21) combine the outputs to provide time selected switching of the triacs (23) controlling the three lights of a traffic signal. The periods of actuation are readily reprogrammed by changing the selector switches.