That simply wouldn’t do, so he initially tried to put together a variation of the clock circuit that [Paul Law] used in his gorgeous relay computer. In the end he couldn’t quite get it working ...

The internal heartbeat of a computer, also known as "clock rate." The clock circuit uses fixed vibrations generated from a quartz crystal to deliver a steady stream of pulses to the CPU.

The coil leads were disconnected from the clock circuit and connected to digital inputs of an Arduino. With a few random() calls, the clock keeps accurate but random time. Unfortunately ...