mechanical-7-segment-clock

A large mechanical 7-segment clock using cheap stepper motors.

Each digit requires its own controller board. The seconds digit acts as the master keeping time using the DS3231 RTC and sending I2C commands out to the other digits. The rest of the digits act as slaves receiving numbers via I2C and displaying the number. The minute tens digit needs I2C address #3 hours digit dress #2 and hours tens dress #1.

BOM

• 28x 28BYJ-48 5V stepper motors
• 28x ULN2003 darlington arrays
• 16x 7HCT 4094 8-bit shift registers
• 28x 608 skateboard bearings
• 4x Arduino nano
• 4x 4 pole screw terminals
• 1x Adafruit ds3231 RTC module
• 56x M4x10 bolts (for anchoring stepper motors to the housing)
• 56x M4x25 bolts (for attaching the stepper casing to the backboard)

Printed parts

• 28x Stepper housings
• 28x Levers

Additional parts

• 1x Backplate
• 28x Digit faces

Assembly

Stepper motor housing assembly

Assembly of the stepper motor housing can be seen by clicking on the image below. Required parts

• 1x 608 skateboard bearing (yellow)
• 1x 28BYJ-48 5V stepper motor
• 2x M4x10 bolts

Printed parts

• 1x Lever (red)
• 1x Stepper Housing (blue)