[time-nuts] 60 Hz frequency and phase measurement

[Adrian Godwin]

I'd normally use an optocoupler.

But it doesn't need to be an 8-pin dip with the mains and low-voltage pins
0.3" apart - it can be a neon lamp and a photodiode, or a photodiode near a
mains-fed lamp. Even an incandescent has a very strong modulation of the
light. You just need to avoid leds that have smoothed DC, and flourescents
with HF ballasts.


On Wed, Jul 3, 2019 at 7:00 AM Bob Albert via time-nuts <
time-nuts at lists.febo.com> 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.
>     On Tuesday, July 2, 2019, 10:01:03 PM PDT, jimlux <
> jimlux at earthlink.net> 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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