eli5: How do you tell a computer what time it is? You can tell a mechanical clock to tick every second using physics but how do you do the same to a non-moving electronic device?

Question

eli5: How do you tell a computer what time it is? You can tell a mechanical clock to tick every second using physics but how do you do the same to a non-moving electronic device?

In: Technology

Answer 1

Inside every digital clock is a crystal that physically resonates like a tuning fork when it is excited by electric pulses. This resonance can also generate electricity, so when the crystal reaches its resonant frequency it affects the circuit driving it and syncs up the electric waveform to its ringing. The circuit can then count the cycles of this waveform – each X cycles one second passes.

Crystals are usually 25 to 5 ppm (parts per million) accurate, so you’d get some drift, but the computer sync up its own idea of what time it is to time services through the internet. Those use much more accurate atomic clocks.