On 7/2/19 10:09 PM, Bob Albert via time-nuts wrote:
I have tried to measure the power line frequency with spotty success. My
best results came from a period measurement, as many periods as the counter can
accumulate. Due to noise, one is never sure at quite what point the source is
measured. Perhaps a brick wall filter would clean it up for a more reliable
measurement.
Of course, at 60 Hz the period is 16-2/3 milliseconds. So the counter should
properly show a 1 followed by a row of 6s, with the last digit bouncing between
6 and 7 most of the time.
If there is a filter used, it will not only remove noise but also short term
variations. But generatlly speaking you don't want to measure those, unless
you are trying to evaluate a rotary generator.
Getting this reading can be a challenge.
The idea would be to look at the phase variations over time across a
neighborhood and see if you can see effects from people turning on and
off loads (air conditioners and sags causing light flicker brought up
the discussion).
It's a whole lot easier for someone to ask "can I put this little
recording box here" than "can I plug something into your wall socket"
The idea is that you get cheap GPS receivers as the time hack and record
*something* at a suitable rate after some low pass filtering, and then
post process. 1kHz sample rate for a day is 86 Megasamples, so it's
not an enormous dataset that needs to be recorded.
Maybe it's just time [sic] for an experiment - stick a wire on an ADC on
a Beagle or Arduino and make some recordings.
On Tuesday, July 2, 2019, 10:01:03 PM PDT, jimlux <[email protected]>
wrote:
On 7/2/19 4:09 PM, Dana Whitlow wrote:
I've always noted that casual attempts to pick up 60 Hz with small antennas
etc see more harmonics and other trash than actual line frequency. But if
you're in an office environment, why not plug something in? It's quite easy
to build a simple passive diode clipper/filter that will plug into a wall
outlet and
which will provide a sort of soft (but clean) squarewave at a voltage level
convenient for lab instruments and with good protection against big spikes
and
other trash riding on the line.
Safety approvals are one obstacle (of course one could use a AC wall wart).
Actually, it's because someone asked me about a science experiment where
you'd place them in a neighborhood outdoors.
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