[time-nuts] Building a mains frequency monitor

[Will]

If you don't want to digitally log the frequency or want .00000hz accuracy then use one of the "tuning fork"? indicators. They have a row of reeds (12 or 20, long time since I have seen one) that resonate at differing frequencies from a few hz.below nominal to nominal frequency and then to a few hz. above nominal.

It gives a quick at a glance showing of the frequency. Ones I saw were used to adjust the phase of generator to AC mains before switching back to AC mains.


Cheers
Will
ZL1TAO


> Sent: Monday, April 11, 2016 at 10:31 AM
> From: "Nick Sayer via time-nuts" <time-nuts at febo.com>
> To: "Bill Hawkins" <bill.iaxs at pobox.com>
> Cc: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Subject: Re: [time-nuts] Building a mains frequency monitor
>
> 
> > On Apr 9, 2016, at 10:20 PM, Bill Hawkins <bill.iaxs at pobox.com> wrote:
> > 
> > The schematic is too simple. There is noise on the power line from
> > switching things on and off, leakage from dimmers and switching power
> > supplies, and the occasional animal that gets across the HV distribution
> > line, not to mention lightning, induced or direct.
> > 
> > A simple capacitor will reduce high frequency stuff. The purist will
> > invest in an L and C that resonates at 60 Hz. Alternatively, use a
> > synchronous motor driving a load with sufficient inertia in combination
> > with a slotted disk and photo pickup. Perhaps an old record turntable
> > will do - but not one with a regulated DC motor.
> 
> I invite you to perform the same experiment with and without the extra filtering and report exactly how much benefit the extra filtering conveys. Otherwise, it’s just Monday morning quarterbacking.
> 
> > 
> > The science fair folks got enough interesting data without all that, but
> > the precision is not known.
> 
> So, the “science fair folks” is me. It wasn’t a real science fair entry, per se. I titled it that way because it seemed to me to be a great idea for someone to use in a science fair if they wanted.
> 
> In any event, unless you’re suggesting that the data is wrong, then I would assert that the precision was sufficient. Perfect is the enemy of good.
> 
> > 
> > The link didn’t have any reference to code at all.
> 
> Really? Did you miss the 3rd and 4th pages? The ones with the Arduino sketch and the Linux monitor program? In C? That code?
> 
> > 
> > This is a way of looking at frequency variations with natural causes
> > that does not require expensive equipment, if done right.
> > 
> > Bill Hawkins
> 
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> If you don't want to digitally log the frequency or want .00000hz accuracy then use one of the "tuning fork"? indicators. They have a row of reeds (12 or 20, long time since I have seen one) that resonate at differing frequencies from a few hz.below nominal to nominal frequency and then to a few hz. above nominal.

It gives a quick at a glance showing of the frequency. Ones I saw were used to adjust the phase of generator to AC mains before switching back to AC mains.