Circuit Diagram - How Digital Clocks Work | HowStuffWorks How Digital Clocks Work. Here's a circuit diagram for the power supply and time base. As we saw in the article on electronic gates, the power supply is the most difficult part! To create the rest of the clock you will need: At least 20 resistors for the LEDs in the 7-segment displays (330 ohms would be fine.)Author: Marshall Brain Simple Digital Clock using LM8650 IC Circuit | Homemade Apr 15, 2019How to set the time in this digital clock. 1. Initially you would need to keep switch S6 pressed 2. Next press S4 to set minutes. 3. Press switch S5 to set hours. The output signal for the above explained ON/OFF control of appliances may be acquired from pin17 of the IC.