Each servo motor requires a PWM signal to control its position, and with 28 servos needed for the clock, the Arduino Mega’s capacity was quickly exceeded. To overcome this limitation, Klements ...

Making a servo tester using an Attiny85 micro chip, Attiny45 also works for this project. This diy servo tester is as good as ...

This tester revolves around an Adafruit 16-channel servo driver and an Arduino Uno. The servos show up on the screen in groups of four, and can be tested four at a time with the pots.