Crazy Clock v0.8.1

by nsayer.
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2 layer board of 0.85x0.48 inches (21.62x12.09 mm).
Shared on November 23rd, 2014 02:48.

Ticks randomly, but keeps “perfect” time.

A single AA battery will run it for 18 months-ish. Connect ‘clock’ terminals to a lavet stepper motor style clock movement.

NOTE: This version has incorrect crystal loading capacitance. It runs ~120 ppm fast. There is a more recent design that fixes this.

Firmware.

BOM:

  • R1 - 10k
  • R2 & R3 - 100R
  • C1 - 10 µF
  • C2 & C3 - 22 µF
  • C4 - 0.1 µF
  • D1 & D2 - BAT54A
  • L1 - 47 µH
  • IC1 - ATTiny45
  • IC2 - NCP1402 3.3V
  • Y1 - 32.768 kHz, 10 ppm

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