Bus stop indicator (CD4516, CD4514, 555, KD9300)

The figure shows the bus stop indicator circuit. The circuit is composed of 555 monostable delay circuit, counter IC2, decoding display IC3, delay audio circuit, etc.

The monostable delay circuit is composed of 555, Rt, Ct, etc., and its delay time is td1=1.1RtCt. Counter IC2 is a reversible counter CD 4516 that can be preset with a 4-bit binary number . IC3 is a 4-bit latch 4-16 line decoder. The audio circuit is composed of music integrated circuit IC4 ( KD 9300) and speakers.

When the switch AN is pressed, the delayed pulse output by IC1 is added to the counter IC2. IC2 counts by adding 1 (subtracting 1), and its output Q1~Q4 enters IC3 for decoding. The decoded output is then passed through the IC5 delay circuit. Feedback to IC3 for control, delay and display for a period of time td2 where td2=1.1R AC A. At the same time, the output of IC5 controls the audio circuit IC4 to output audio signals to drive the speakers to emit audio signals.

Every time the car enters a stop, press AN and the above process will be repeated to facilitate passengers getting on and off.