Detailed 7-Segment 24-Hour Clock

Power from the battery (VCC) and ground (GND) feeds the timing source, where a crystal oscillator produces a very fast, steady tick. That tick goes into a divider made from flip-flops, which repeatedly halves the frequency until it becomes a clean 1-pulse-per-second signal. Each 1 Hz pulse advances the BCD counters for seconds, minutes, and hours, and every digit's BCD lines feed a decoder that turns them into the seven segment signals used to light up seven segment displays.

Click inside components to learn how each part of the clock works.