Introduction: An LED Clock Without a Micro-controller

About: Self-made, well made

As it seems, I like to make different clocks. I have built and designed numerous electronic and mechanical clocks and this one is another one. My first electronics clock required several iterations and I learned a lot.

The presented design is improvement of the older design – it is smaller and cheaper to build than the previous versions. Additionally, I have documented the process much better this time.

The clock is electronic, without any microcontroller. The time is generated from a 32.768 kHz crystal and by counting the crystal oscillations the time could be shown. The numbers are constructed with LEDs in a seven-segment display formation.

In the following the BOM is introduced, thereafter the design is introduced and eventually the assembly process is shown.

Step 1: BOM

Everything through hole components (I got everything from Aliexpress)

  • 74HC393N - 8 pcs
  • 74HC32N - 3 pcs
  • 74HC08N - 3 pcs
  • 74LS47N - 6 pcs
  • NE555N - 1 pcs
  • 8-bit switch - 3 pcs
  • 6mm button - 2 pcs
  • Resistor 10k - 9 pcs
  • Resistor 1M - 5 pcs
  • Resistor 1k - 1 pcs
  • Resistor 560Ω - 52 pcs (follow the comments in the end, I used 560Ω)
  • Capacitor 100n - 15 pcs
  • Capacitor 16p - 1 pcs
  • Capacitor 8p - 1 pcs
  • 32.768kHz crystal - 1 pcs
  • Led - 128 pcs (you can use any color you like, 3 or 5mm LEDs, I used 5mm)
  • M3 screws (>5mm) and nuts - 4 pcs
  • 3 PCBs

I would strongly recommend using IC sockets instead of directly soldering the components

Step 2: Design Explanation General

Step 3: Design Explanation - 32.768Hz Signal

Step 4: Design Explanation - 1 Hz Signal

Step 5: Design Explanation - Clock Logic

Step 6: Design Explanation - Logic Schema

Step 7: Design Explanation - 7 Segment

Step 8: Design Explanation - Voltage and Power

Step 9: Design Explanation - PCB

Step 10: How to Solder

Step 11: Ready Clock

Step 12: Conclusion

I hope this instructable was helpful and interesting to read.

Maybe it can inspire other people to use counters or build their own clock.

If you would like to purchase the PCB gerber files then follow this link to my etsy shop:

Lighting Challenge

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Lighting Challenge