Hi all, wonder if anyone can suggest what is going on here.
I have a couple of electronic time switches, nice range of settings they have too :-) They use an internal battery to keep time when the mains fails.
Funny thing happened; within a month of each other (at about guarantee ending time), they started losing time very badly - almost an hour a day eventually. Unplugged them both, left them to one side, set the time correctly to have a look just how bad the drift was, where I could see them properly. Funny thing happened, they both started keeping good time again!
Looking inside, the clock board has 3 ceramic caps, a crystal and chip epoxy bonded to the board. Small rechargeable battery feeds into it. I think either the ceramic caps are rated a bit too close to the battery voltage and leaking a bit when at charging voltage, but okay on battery only.. or something odd is happening with the battery or it's charging circuit. Not done any tests yet (not that important to fix). Guessing the former, I could just connect a resistor in the clock supply to take the voltage down a bit, but any suggestions as to what might be the cause of the fault - probably too subtle for me!
Monster