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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details.

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Old 26th May 2024, 7:58 pm   #1
Bignaughtydog
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Default Electromechanical clock buzzing with no movement.

Hi all. I recently acquired a double faced 240 volt non-operational clock. It has two electro-mechanical devices that buzz loudly which indicate the coils work but the magnetic wheel won't turn when the AC electromagnet applies a field to it. This is the same for each device.

The gears seem to run freely under hand rotation. Their is no build up of grime and no excessive play.

I have measured both coils at 1.2 and 1.4 kOhm. I think the coils could do with re-potting but with no excessive windings going astray from the bobbin.

The magnetic driven gear wheel, when firmly touched with a screwdriver and whilst under mains power, makes the whole unit silent.

These identical units look quite simple but are experiencing exactly the same issue as far as I can see.

I have attached images of one of the devices.
Thank you in advance for any feedback.
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Old 26th May 2024, 9:46 pm   #2
Nickthedentist
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Default Re: Electromechanical clock buzzing with no movement.

Hello and welcome.

What happens if you give the rotor a spin with your finger, when power is applied?

Nick
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Old 26th May 2024, 10:20 pm   #3
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Default Re: Electromechanical clock buzzing with no movement.

It looks like in the last picture, there is a small knob on the motor shaft to start the motor rotating. If the mechanism is free, it should then rotate easily.

Christopher Capener
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Old 26th May 2024, 11:09 pm   #4
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Default Re: Electromechanical clock buzzing with no movement.

These kinds of movements are not self-starting. You have to spin the motor by hand when the power is applied.
You have to spin it in the correct direction as it can run in reverse.

I think you can even make it run at double speed if you spin it fast enough!
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Old 27th May 2024, 6:23 am   #5
Bignaughtydog
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Default Re: Electromechanical clock buzzing with no movement.

Thank you for all your kind replies and welcomes

I have managed to keep one of the mechanisms going with a spin under power. However, the minute hand does 1 complete revolution in 1 second.

I connected the second device in parallel (if one dies the other lives and as I found it) with the first to power assuming it may alter things but no effect.

I made a 4 second video which turned out to be 11 meg in size so can't upload.

Thank you all again.
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Old 27th May 2024, 11:36 am   #6
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Default Re: Electromechanical clock buzzing with no movement.

I usually upload videos to my Youtube account and post a link in the forum. Do you mean the clock keeps stopping, or is it running slow (unlikely).
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Old 27th May 2024, 11:40 am   #7
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Default Re: Electromechanical clock buzzing with no movement.

Quote:
Originally Posted by Bignaughtydog View Post
I have managed to keep one of the mechanisms going with a spin under power. However, the minute hand does 1 complete revolution in 1 second.
That seems almost inconceivable! It would be 60rpm, nearly as fast as a 78rpm record!

Hopefully you can post a video by some means.

Connecting the other clock in parallel shouldn't have any effect on either (unless of course a shared fuse blows, in which case they'd both stop).
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Old 27th May 2024, 12:06 pm   #8
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Default Re: Electromechanical clock buzzing with no movement.

There are not enough gears for it to be a regular movement.
I reckon it should be pulsed and that you were lucky not to have burned the coils out.
Start with 12 volts and pulse it and if that works you will need to find or make a master clock. It is unlikely to be more than 40 volts.
The rotor looks like it is shaped so that it will always move in the same direction with each pulse.
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Old 27th May 2024, 12:11 pm   #9
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Default Re: Electromechanical clock buzzing with no movement.

Ah, a stepper motor. I completely missed that!
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Old 27th May 2024, 12:12 pm   #10
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Default Re: Electromechanical clock buzzing with no movement.

Quote:
Originally Posted by Bignaughtydog View Post
Hi all. I recently acquired a double faced 240 volt non-operational clock.
Where did the information that it's a 240 VAC clock come from?

Quote:
Originally Posted by Bignaughtydog View Post
However, the minute hand does 1 complete revolution in 1 second.
As Refugee says that suggests it a one pulse per second clock. If it gets 50 cycles per second, ie mains frequency it'll run 50 times too fast.
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Old 27th May 2024, 12:27 pm   #11
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Default Re: Electromechanical clock buzzing with no movement.

I doubt it even has a second hand because there is not enough gears for that.
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Old 27th May 2024, 12:28 pm   #12
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Default Re: Electromechanical clock buzzing with no movement.

Sorry I should have said one pulse per minute.
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Old 27th May 2024, 12:48 pm   #13
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Default Re: Electromechanical clock buzzing with no movement.

Quote:
Originally Posted by Station X View Post
Sorry I should have said one pulse per minute.
Oops
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Old 27th May 2024, 1:33 pm   #14
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Default Re: Electromechanical clock buzzing with no movement.

https://youtu.be/fM5KVdcNK80?feature=shared

Thank you for your replies and the video advice.
Please follow the link above.
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Old 27th May 2024, 2:29 pm   #15
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Default Re: Electromechanical clock buzzing with no movement.

Quote:
Originally Posted by Bignaughtydog View Post
https://youtu.be/fM5KVdcNK80?feature=shared

Thank you for your replies and the video advice.
Please follow the link above.
Thanks.
The consensus here is what you have is a pair of slave movements that would have received one DC pulse each minute from a master clock. The voltage required is likely to be considerably less than 240 so please don't continue to test it on the mains.
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Old 27th May 2024, 6:09 pm   #16
Bignaughtydog
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Default Re: Electromechanical clock buzzing with no movement.

Thank you everyone for the feedback.

Perhaps it was errant to test under mains voltage.
The wires are bulky and so mislead me in that respect.
The coil survived but if needed I could have wound a new one. I do have a few spools of wire that are close to that on the coil.

Moving forward I would need to find a voltage that would be
Sufficient to drive at the correct speed and perhaps a 555 timer circuit or similar that would pulse that voltage every second.

My thinking is that if the mechanism, as has been stated and have found to be true through experiment, is not a self starting mechanism then how would pulsing work? It would need to be hand started every time between pulses. Perhaps the magnetic wheel holds just enough rotational momentum to keep it going.
Perhaps I'm disappearing up my own whatnot with this thinking.

This is the only idea I can think of at the moment is that the mechanism is a sweep and not analogous to a digital pulse mechanism.

Hope that makes sense and thank you to all once again. I never though it would get this much feedback. I clearly posted my question in the right place.

Steve, Bulgaria.
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Old 27th May 2024, 6:15 pm   #17
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Default Re: Electromechanical clock buzzing with no movement.

Just connect whatever DC voltage you have to the coil and check whatever the "Motor" steps. It's survived 240VAC so something like 12VDC won't do it any harm.

Chances are it'll make half a step when the voltage is applied and another half step when it's removed.
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Old 27th May 2024, 9:47 pm   #18
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Default Re: Electromechanical clock buzzing with no movement.

I have had a quick look on the web.
The pulses are most likely to be 24 volts but no harm will be done if you try 12 volts first.
https://medium.com/@steveharding_763...k-37bf77035ac0
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Old 28th May 2024, 9:44 am   #19
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Default Re: Electromechanical clock buzzing with no movement.

If you only want to demonstrate the clocks running, a 555 timer might do, but it would not give an accurate enough interval between pulses for a usable clock. How about a crystal controlled clock module giving (probably) one pulse per second and then a further divider?
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Old 30th May 2024, 7:34 pm   #20
Bignaughtydog
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Default Re: Electromechanical clock buzzing with no movement.

Just found this website after a YouTube search www.electric-clocks.co.uk

The item I need is in the screenshot just out of interest ?

Here is the link to the YouTube video.

https://m.youtube.com/watch?v=vT9Idc...ZSBkcml2ZXI%3D
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