On Sun, 16 Apr 2006 11:45:56 +0100, Andy Wade
wrote:

Derek ^ wrote:

The traditional approach assuming the outages were brief, was to use a
cheap oscillator (an astable mutivibrator) running from a back up
battery when the mains feed was down.

Yes, that's why I was careful to say "the biggest problem with using the
mains alone ..."

Cheap clock radios are the only things I've seen that have used crude RC
oscillators to cover mains outages, and their timekeeping is utter crap
- 5 min error in half an hour!

Presumably the back up oscillator wasn't adjusted accurately if at all
during manufacture, not surprisingly. people were used to having to
set the clock.

In the '60's most audio equipment, cheap record players etc around
here (Leeds) used to emit a series of peeps at about 6-00 pm, as
schoolkids we believed it was to reset the timeswitches governing the
streetlights once per day. WCHBW

DG