Allowed range of the 60Hz mains frequency

OK thread.. not many electronic threads on SED....

As an aside; With a 'scope and DDS Sig. Gen. you can measure the local phase and watch it drift around. (I set my 'scope to AC couple and then dial the freq. of a square wave from the SG till the edge stands still.)

George H.

If I really wanted to see something like that I would try to receive the

60kHz carrier from WWVB(NIST) and divide it by 1000.

Your explanation makes it even worse. Every engineer knows (exactly) what "infinite" and "exactly" mean.

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** My method is to use an audio gen plus frequency counter and create Lissajous patterns on an *analogue* scope in X-Y mode.

Set the gen to 500Hz or 600Hz and tweak the frequency to stabilise the pattern.

With some patience, try 5000Hz or 6000Hz instead so you have 0.01 Hz resolution on frequency measurement.

FYI:

for a really psychedelic experience, try feeding the X and Y inputs of a scope with L and R stereo music signals.

...... Phil

Goniometer.

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** Wow.

..... Phil

Now that the mains waveform at some places only slightly resembles a sine way, the Lissajous pattern can be quite interesting :-).

You must be close to Colorado. Here on the east coast I don't think I'd be able to see the carrier. I could pick it out of the noise with a sharp filter maybe.

--

Rick C

Not a popular sport in Sydney. You have to get quite a bit closer to the equator for that to be an option, and Sydney backyards are rarely big enough to accommodate a crocodile worth wrestling, even if you could be bothered getting one shipped south.

Boxing kangaroos are in equally short supply.

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Bill Sloman, Sydney

In extreme cases there can be large deviations. I recall my sister telling about the great NE blackout. She worked in a radio station in Oklahoma. During the blackout their electric clock lost several minutes, although I can't say just how many. Then for some time after that it gained slowly until it was correct again.

Bill

It used to be that the power companies in the US were required to maintain a very tight long term stability. That meant that for the long term an electric clock was very accurate. For the short term not so much. A few years ago the requirement was relaxed, and the long term stability is not nearly what it used to be. I have a clock that synchronizes its time to the power line. Since the relaxation of the requirement the clock has been gaining, on average about 30 seconds in 3 or 4 months. The short term stability is much lower.

Bill

That claim is dubious, at best, since the OK isn't on the same power grid as the NE. Not even next door.

If you can pull the signal out of the noise, the carrier is no problem. Any receiver is capable of reconstructing the carrier, no?

In this day and age when cheap timepieces - like my $5 watch - manage an accuracy of a few ppm, deviations of several seconds per day doesn't even approach 'exact'. Commenting on that isn't being pedantic.

The comment wasn't about $5 watches, moron.

Both mains clocks and personal watches are about timekeeping with the same end purpose - to help the user know what time it is, how much time has elapsed and so on.

Some used the MM5369 from National Semiconductor to divide a NTSC colorburst crystal to the desired line frequency, so those clocks were immune to changes in the line frequency. With GPS receiver/antenna packages available for under $10, it's possible to build a very accurate clock for a reasonable price. Lookat the GPS modules for drones. The Ublox Neo 6/7 series output 1PPS, as well as the NMEA code.

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)

e

sajous patterns on an *analogue* scope in X-Y mode.

ttern.

lution on frequency measurement.

scope with L and R stereo music signals.

I got a $3 LED clock kit from AliExpress a couple of years ago. It's based on an AT89C2051 chip and I bought it mainly because I was curious about how accurately it could be made to run by tweaking it. I never did go beyond lighting it up once.