Historic Journal Reveals Rare Flip Clock

[mrsteve7]

Some time Googling yielded the below explanation. It's a matter of the current increasing when voltage is increased, exceeding the coil's design parameters and heating it to the point of failure. Also, we have our empirical evidence so eloquently described by flipclock_nl: "... the casing around the gears was plastic and had 'somewhat' changed shape, let's put it that way".

Quote:
A motor is basically a coil wound in a specific way. When you put a higher AC voltage(V) on a coil(L) it will generate more current(i) in the same time(t) (dV = L*di/dt). Since you're putting twice the amount of voltage on it, twice the amount of current (2i) will run through your motor.

A coil is basically wire. Wire has resistance(R) and uses power(P) (P = R * i^2). The wire was not engineered to handle the increased amount of power it was designed for: (2i)^2 = 4*i^2 as opposed to the designed i^2. If the engineers who developed the motor had a 20% safety margin, you're going past that by... well, a lot. This would result in burning the wire since the wire can't disperse the heat it generates.
End quote

It seems to me we have a reverse idiom here: 'You takes your chances, you pays your money'

Mackey: The 20% design margin mentioned is interesting and would explain being able to operate Japan 100v on 120v

[davidm]

I understand the relationship between power, voltage, resistance and current, I've been doing electronic repairs on radio broadcast equipment, video, audio and more for over 40 years.

I said previously on this thread: "I know you'd think it would burn the motor coil out, but would it?"

There does not appear to be any voltage rating on Mackey's Caslon 101 only the 50/60Hz selector, which implies that it can run on 120v or 240v

Would someone with a few basic non radio 120v flip clocks measure a few motor's coil resistance using the method in my previous post and post the results please?

[Mackey]

mrsteve7 Thanks for doing the research. Unfortunately this weekend I have to work on my son’s car so I might not get to do any testing. We’ll see...

[mrsteve7]

Further thoughts:
Why then would seemingly all subsequent Copal motors (to Mackey's) be explicitly marked with a voltage if this were not a design factor of the motor coil (e.g. 117v, 240v)
Why not just Hz?
Why do we not see markings of a voltage range such as '100 - 240Vac' ?
Why would a manufacturer unnecessarily use a heavier gauge wire, or more of it, in the winding (to handle higher current) if it weren't necessary on the basis of cost when mass producing?

For davidm's curiosity:

Note: one leg lifted on motor for the measurement

[flipoclock]

Thanks for the photos and measurement, will see if I can do some of my own tomorrow.

I would have plenty of parts motors which could be repurposed for a test of sorts when needed...

[davidm]

mrsteve7 Thanks for the measurements of around 3kΩ on those two 120v Copal 2's, that answers the question on Copal 2 motors.

The resistance of the windings on the Copal 2 240v motors is around 11kΩ

The power of both motors on their correct voltages by the formulas is close to 5 watts.

So if you ran a 120v motor on 240v it wouldn't take long before the smoke came out as the power goes up 4 times!

And if you ran a 240v motor on 120v it would be surprising if it ran at all as you would have a quarter of the power!

It would be interesting to know the motor coil resistance of Mackey's early 101 to see if it's the same as a 240v copal 2 motor.

It's still a mystery to me as to why you can change the frequency to 60Hz on that early Caslon 101 but also run it on 240v!

[Mackey]

It's still a mystery to me as to why you can change the frequency to 60Hz on that early Caslon 101 but also run it on 240v!

Well, actually ... there are a few countries/places that run 220V with 60Hz ... most notably South Korea. That might be the answer right there. Others: Peru, Montserrat Islands, St. Kitts & Nevis Islands.

And in fact, I did notice that the HJ Copal Caslon did not hardly want to run on 110, but started up rather quickly on 220V.

On my 110v caslon 101 the resistance measured was 6.36 kΩ and on the HJ Calson it read 17.75 kΩ

[davidm]

there are a few countries/places that run 220V with 60Hz ... most notably South Korea

Well that explains it, and Wikipedia states that the Korean peninsular was occupied by Japan in 1910 before being divided after the 2nd world war.

There's more history to that flip clock than I'd have thought.

[Mackey]

...
There's more history to that flip clock than I'd have thought.

That's started to become a major reason I like looking into those clocks. I like to think about the era in which they were made and the look at the history. I'm not a "real" history buff .... Let's just put it this way .. I was a very good student "Magna Cum Whogivesacrap" and all that .. and the only test in college that I ever flunked was in a history course. But since now I don't HAVE to study history, it's become a thing for me. Most videos I watch now are history related, plane crash reenactments (I do not know why), trials and crime mystery type (or history of the gangsters of the 20s and 30s). I just like thinking about those that have gone before. I've got clocks from the beginning of the industrial revolution, the Great Depression and of, course from the psychedelic 60s and the drug and disco fueled 70s. Whenever I look up a flip clock advertisement, I also check out the front page to see what was happening (typically Apollo stuff and lots of Watergate related stuff as well as Vietnam, of course).

Anyway, I do appreciate the expertise that you all bring to this forum. It makes this a much more interesting hobby.

[NoTime]

I realize I'm resurrecting an old thread here but I wanted to add a piece of data that I was looking for and couldn't find anywhere.
I just got a 100v clock from Japan and asked myself the same question about running it on 120v power. I had a suspicion that the 100v and 120v motors were the same, just with a different sticker to match the country they were intended for.
Well, I was wrong.
The resistance of my 100v motor is ~2.4kΩ.
Measurement taken on a 120v motor earlier in this thread by another member is ~3kΩ.
So, there is a difference.

[Mackey]

So, there is a difference.

I ran my Copal 228 that is rated for 100V on 120 and found it kept great time, but after a while the clock became noticeably warm. Since then, I've used my 120 to100 V converter and the clock runs cool. I've no intention of running 100v clocks on 120 volts going forward.
Thanks.