Main Content

A couple of months ago I built a two digit mechanical 7 segment display which I turned into a countdown timer. It came out quite well and a number of people suggested doubling up on the display to make a clock. The problem was that I was already running out of PWM IO on my Arduino Mega and didn’t have enough available for the second or third digits. I was then pointed in the direction of these PCA9685 16 channel PWM drivers which operates over an I2C interface. These made it possible to drive the 28 servos I needed all using the two I2C pins on an Arduino. So I got to work building a clock which now uses a DS1302 real time clock module to keep the time and two 16 channel servo drivers to control the 28 servos used to make up the display, all powered by an Arduino Uno.
If you enjoy this Instructable, please consider voting for it in the Clocks Contest
To build your clock, you’ll need the following supplies in addition to some basic tools:
Arduino Uno
DS1302 Clock Module
2 x PCA9685 16Ch Servo Drivers
28 x Micro Servos
Ribbon Cable
Male Pin Header Strips
Female Pin Header Strips
3mm MDF
Black Spray Paint
5V 5A Battery Elimination Circuit
12V Power Supply
For this project you’ll also need some 3D printed parts. If you don’t already have a 3D printer and you enjoy making thing then you should definitely consider buying one. The Creality Ender 3 Pro used here is affordable and produces pretty good quality prints for its price.

3D Printer Used

Link to article