Of course, there’s nothing unusual about using 7-segment displays, especially in a clock. However, [Edison Science Corner] didn’t buy displays. Instead, he fabricated them from a PCB us… ...

His clever solution is to use an Arduino Uno R4 and take advantage of the onboard DAC. To turn on a segment, he connects a segment to a GPIO pin set high while sending 3.5 volts out of the DAC ...

Output devices: Motors, solenoids, bulbs, buzzers, relays, LEDs, 7-segment displays. Circuit diagrams show connections. Relays: Electrically operated switches ...