You'd expect even a fairly good quartz to deviate by more than a minute a year from temperature fluctuations. Relying on AC frequency should allow your clock t

You'd expect even a fairly good quartz to deviate by more than a minute a year from temperature fluctuations. Relying on AC frequency should allow your clock to operate for many years without gaining or losing time as long as the AC frequency is compensated, which it needs to be or someone is stealing energy.