The Spooky Action Of Mechanical Frequency Meters

My brother was a lineman in Texas for Swepco and said he had seen a few installed in some of the older sub stations. As for you current draw concerns, they were switched so they were only on when being read

Todd Corley

Now I would have tried it out before taking it apart. :-/

Dr Andy Hill

😮 it’s a harp, in reverse! That’s really cool :-) Thank you for sharing 😍

Ewen McNeill

At that low power consumption, it would almost be worth installing it 😆

Antony Curtis

I've only every seen purely mechanical versions of these -- the unit would be clamped to a machine case and the vibration caused by the rotation would set up the resonance in the readout fingers. EDIT: AvE showed one off on his channel last year. https://www.youtube.com/watch?v=weDiELpXlpk

The first company I worked for, circa 1979, had a power line frequency issue causing them problems with one customer. The microcomputer used power line frequency for the system time. This system would not keep accurate time. After much investigation they found the grid was feeding power at two different frequencies, both close to 60 Hz, but not identical.

Steven Ruhl

No.

Fran Blanche

A tuning fork as two prongs that sympathetically vibrate together. These would be tines, like in a music box - but they are absolutely not Radium paint or luminescent.

Fran Blanche

I was thinking the same thing

David Peaker

Is that radioactive lume on those tabs?

nj Phil

The individual tines are actually tuning forks, and they DO have some radium paint on the end for a glow-in-the-dark experience.

Chuck Kirchner

I have a slightly older one that reads from 57-63 cycles per second (that's how I know it's pre-1965). The neighboring tines vibrate more than the ones on your unit, and I suspect mine wasn't made to the same specs. Mine is also in a much cheaper plastic case with yellowed plastic window. I don't know if this link will paste here, if not you can view a video of mine in action on my PetrosArgy youtube page. https://youtu.be/G5ZWTlkIu1o

Peter Argyropoulos

One of the most fun episodes yet! Thanks, Fran, and Merry Christmas!

Rick Lett

perhaps you should check it with your geiger counter...that white paint at the end of the acutators looks like it could be raduim

I would think the way the coil is wound might be just lazy winding, but the plates I would think are there to shape the specific magnetic field generated by the electromagnet.

Fran Blanche

You always come up with ingenious things to show that I never imagined existed.

John McCormick

Really ingenious

The similarity to a guitar pick up coil is probably not surprising :) guitar= mechanical vibrations to electric frequency. This thing electric frequency to mechanical vibrations.

Was placing it into the 50's style wise, but good reasoning.

I guess the market for used frequency converters is different on your side of the Atlantic. Here in Sweden you can buy used NFO Sinus for maybe the equivalent of 100 US dollars, which is ridiculously cheap for such a quality product. With one like this, you could have swept the entire scale up and down. On the other hand, I can not buy an old mechanical frequency meter for money, they were only available in power plants. Someone who wants to swap one for a bunch of BCD switches that I have left over, as Fran showed in the previous video ...

Emil Almberg

I noticed that the coil appeared to be skewed in thickness towards the outside. That would make the field stronger further out the tine while keeping the winding length to a minimum - might also be related to the fine tuning of the resonances. Wonder also if the angled brackets mounted along the tine exit were done because of some mechanical resonance dampening effect. Just a few thoughts. Thanks!

2:25 The number in the side is a NATO stock number. https://www.iso-group.com/Public/Search_Results.aspx?ss=6625-00-993-3466

Jac Goudsmit

I just love these electro mechanical devices- such precision engineering as well as ingenuity in their iterations. Thanks for showing these delightful devices, one of the reasons for enjoying your channel so much. Thank you Fran.

Mike Hughes

The primary market for these meters was for adjusting the speed of portable generators. Centering the scale on the desired frequency made it more likely that the actual frequency would fall within the limited range of the meter. I'm sure meters for 50 Hz service were also produced.

HarveyB

I have seen purely mechanical versions on generators that worked from the engine vibration so you might be able to make that work without even using an amp!

HarveyB

The "on the cheap" way to do this would be a signal generator into an audio amplifier to a step-up transformer (i.e. mains transformer wired "backwards"). It's only a couple watts, so even a 10VA transformer would be plenty. The thing *I* want to see is a 60Hz + 70Hz waveform to get two tines to move. Finally, of note, is that it goes from 55 to 75 Hz making it wholly useless for 50Hz mains when it could have been 45 Hz to 65 Hz just as easily. :/

Jason Olshefsky

Neat indeed! My favorite use of this technology was it's use in high end radio control models where the vibrating reeds were used as relay contacts. A friend had an RC airplane with 4 channels of reed that allowed pitch, yaw, roll and throttle control with a radio transmitter small enough to be held in his hands! Truly amazing miniature tech for the 1960's! It worked on a CB channel and sent 8 audio tones, one for each direction of each function!

HarveyB

As a bass player, my first thought would be to set it on my bass amp cabinet, turn it up, and start playing stuff on the A string. See if it will mechanically couple.

Hertz = 1965 or later. Prior to that, it was cps.

What a neato meter, and such a simple but ingenius way of it's operation!! An audio frequency generator (or a badly tuned bass guitar), plus an amplifier and a small mains transformer in reverse should work for making it oscillate at higher frequencies.

Anton

Amazing. The ingeniousness of these pre-MCU analogue technologies is really inspirational. It reminds me of a doctor's dictum to their medical students that goes, "Think of horses before zebras". To me it means that not everything needs a complex solution with software running on a micro. Today there would be a PIC or AVR, or whatever, running a clock and some firmware in memory, and an analog-to-digital converter to bring in the the line signal to measure the sine wave. Thanks for showing us this impressive little meter from a pre-MCU era, Fran. Another elegant idea realized in a cool product from back in the day.

Peter Knazko