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 < [email protected]> 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 < > [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. > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
