Can someone describe in detail how "auto-set" clocks work? I'm not talking about Atomic time-signal clocks, rather, the AC models that get the approx. time instantly when plugged in. Is an internal wristwatch type of circuit feeding the main display?
I bought a $15 Sony auto-set alarm clock that was 3 minutes fast out of the box, then a few hours later became accurate within about 20 seconds, but never got much better than that. User manuals mention a factory preset time and lithium batteries, but seem deliberately vague about the mechanism.
Jack