Bus stop indicator circuit diagram

IC 1 (555) and RtCt form a monostable circuit, and the timing time td1=1.1RtCt. When AN is pressed, the timing pulse output by IC1 is added to IC2. IC2 is a preset 4-bit binary reversible reader CD4516; IC3 is a 4-bit latch 4-16 line decoder. Press once for each station. AN, then IC2 and IC3 perform the calculation of adding 1 (or subtracting 1), the output Q1~Q4 of IC2 enters the decoder for decoding, and then the decoding output is fed back by the IC5 delay circuit to control IC 3 .