Sam Goldwasser wrote:

Bill Jeffrey writes:

The topic of the thread was remote-reading electrical power meters -
you could Google it. The gist of the topic was that there are many
ways in which a remote-reading power meter can work. Most cause no
harm or interference of any kind. But one of them involves
"modulating the zero-crossings" in the AC waveform, a signalling
method which can be triggered and read from a remote location.
Apparently, this technique can cause extra zero-crossings to show up,
and a clock which counts time by counting zero-crossings will gain
time. There is an easy fix, IIRC.

So the question becomes, has the power company retrofitted the power
meters in your neighborhood recently?

I'm glad my semi-antique (30+ years) clock radio still uses a synchronouc
motor. Full cycles are all that matter!

Yup. But they are gettign harder to find. Electronics is cheep!

How did a signally scheme like that ever get approved? A large precentage
of AC powered clocks must count zero crossings.

Actually, the post that I read may have been referring to the signalling
scheme used by the X-10 products - a short burst of 120KHz at the zero
crossing. IIRC, the "easy fix" was to add a 0.001 cap across the clock
circuit, which would probably reduce the level of 120 KHz to an
insignificant level. Haven't yet found the post I am referring to, but
there wasn't much more than that.

But, didn't he say he thought there was a crystal in the RCA?

Yes, he did. I assume that the crystal oscillator is there simply to
take over in the event of power failure. For "normal" operation, the
power line frequency (or at least aggregate number of cycles over 24
hours) is much more accurate than any cheap crystal oscillator.

So the next question for the OP is, have you recently installed any X-10
equipment?

Bill