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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 21st Nov 2022, 3:15 pm   #1
Jockmacrea
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Default Only 12 Minutes in an hour ?

I was given an old Brass cased Slave Clock by a friend of mine. The two coils to activate the impulse were fried! I had these rewound.
I then started to develop my own drive circuit and also found a host of information on the web.
Finally, I constructed a Crystal controlled 1 second timer driving a relay which reversed the polarity through the coils. The two coils are connected in series with no centre tap.

After a few popped transistors and corrected wiring, it worked!

Now here's the real problem,
There are two hands on the clock, one big one and one wee one, the wee one is fitted onto the shaft first and then the big one which is secured by a small circular threaded nut. when securely mounted there appears to be enough room for a third hand

However, when I run the clock, the big hand takes precisely 60 seconds to go 360degrees, the wee hand takes precisely 12Minutes to complete 360degrees.

It would seem there may be an issue with the gear train? but I cannot see where it may have been mounted. This is all very strange; can anyone suggest where I may have gone wrong. I'm sure there are more that 12minutes in an hour!!!

Even if an extra hand was fitted how can that alter the 12-minute hour??

I'd be grateful for any assistance.
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Old 21st Nov 2022, 3:51 pm   #2
paulsherwin
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Default Re: Only 12 Minutes in an hour ?

Everything is running 60 times faster than it should be.
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Old 21st Nov 2022, 3:52 pm   #3
TonyDuell
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Default Re: Only 12 Minutes in an hour ?

I think the gearing is right. 12 revolutions of the large hand gives one revolution of the small one. Large hand is a minute hand, small hand is an hour hand as usual.

The problem I think is that you need to give it one pulse per minute, not one a second
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Old 21st Nov 2022, 4:10 pm   #4
Nickthedentist
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Default Re: Only 12 Minutes in an hour ?

Ah, so it was a slave after all!. I wonder who connected it to the mains?!

https://www.vintage-radio.net/forum/...d.php?t=194476

Yes, as the others have said, change your impulse to one per minute, and all will be well.
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Old 21st Nov 2022, 4:16 pm   #5
Jockmacrea
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Default Re: Only 12 Minutes in an hour ?

Quote:
Originally Posted by paulsherwin View Post
Everything is running 60 times faster than it should be.
And I spent all that time making a dead dead accurate 1 second pulser.

Ho hum, back to the drawing board.

Thanks for the reply.
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Old 21st Nov 2022, 8:18 pm   #6
Jockmacrea
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Default Re: Only 12 Minutes in an hour ?

Quote:
Originally Posted by paulsherwin View Post
Everything is running 60 times faster than it should be.
Thanks Paul
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Old 21st Nov 2022, 8:36 pm   #7
Ed_Dinning
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Default Re: Only 12 Minutes in an hour ?

Hi Jock, looks like you will need a further divider chip on your little circuit

Ed
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Old 22nd Nov 2022, 1:07 pm   #8
Jockmacrea
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Default Re: Only 12 Minutes in an hour ?

Quote:
Originally Posted by Ed_Dinning View Post
Hi Jock, looks like you will need a further divider chip on your little circuit

Ed
Cheers ED, yep I think that will fix it.

Meanwhile I found this:-
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Last edited by Jockmacrea; 22nd Nov 2022 at 1:22 pm. Reason: added pic
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