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Topic Title: Chloride gent slave clock from the Royal Mail.
Topic Summary: Workaround
Created On: 10 August 2014 10:02 AM
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 10 August 2014 10:02 AM
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unshockable

Posts: 848
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Yesterday I was helping the chippies to move a doorway and after moving the cable and placing the single socket above the door I had a look at the large Royal Mail clock the interior designer had picked to go there.

I presume the many slaves daisy chained off the one master? Can anyone suggest a workaround? Is there a modern driver I could use without removing the mechanism.

Thanks
 10 August 2014 12:35 PM
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slittle

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I think most of the old master clock systems simply gave a pulse every minute. Certainly the one I used to maintain at a Fire HQ did.

Shouldn't be too hard to come up with a timer to do that. You just need to make it pulse fast for setting otherwise it takes forever.

Stu
 10 August 2014 12:55 PM
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AncientMariner

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Some Master/Slave Clock systems pulse every 30 seconds.
Also the polarity of the pulse swaps for each pulse. This then means that the Slave Clock can use a polarized electromagnet to ratchet the mechanism round. (Same idea as the polarised bell found in telephones of the 1970s)

Edited to add that the ship I'm standing on the bridge-wing of in my photo, had such a system.

Cheers!

-------------------------
Clive S Carver GCGI IEng MIET
 10 August 2014 01:09 PM
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sparkingchip

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My high school had such system and if my memory serves me right the slave clock minute hand clunked forward in thirty second increments rather than having a smooth progression.

Andy

This was noticeable because of the size of some of the clocks and their hands, the tip of the hand moved over a inch and the hand would quiver having advanced.
 10 August 2014 01:31 PM
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John Peckham

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I know these clocks well having done the Post Office clock course as part of my training. From my distant memory they were connected in series with 8 in a loop and received a 30s 24V pulse from a large pendulum clock known as "Clocks Pulse GMT 34". Later a lot of the pendulum clocks, which were a work of no expense spared engineering excellence , were replaced with a box of electronics to deliver the pulse.

I have an old small one in to which I fitted a quartz movement. I can remember scrapping loads of these placing them a bag at a time in to the wheely bins so as to not upset the dustman. I wish I had enough foresight to keep them. Later in my career we started to dispose of large buildings in London full of these clocks that were left in the buildings. On one site in London on the main sorting floor there were 8 No. about 3 foot in diameter clocks I think marked GPO GR that were left in the building for demolition! I would not mind betting your interior designer was the recipient of one of these clocks?

You could devise a bit of electronics to deliver the 30s pulse but probably easier to replace the movement with a quartz movement.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 10 August 2014 01:51 PM
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sparkingchip

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I presume in its simplest form the main clock regulated by the pendulum ratched over a cog every thirty seconds to operate its own hands and a contact on the cog sent a pulse to the slaves.

Andy
 10 August 2014 02:22 PM
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Zs

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Unshockable,

I've made a few clocks and simply buy a not very nice clock of the same or similar dimensions, take out the workings and use them behind a 3mm mild steel face ( I etch them with all sorts of nasty stuff and blue them with a blow torch or the like but that's by the bye) if necessary cut new funky hands or do a job on the ones that come with it. It's easy.

When taking the bought clock apart, just look out to keep the hands and their washers all in the same direction when you put it back together. You'll be needing to re use the same hands though, so watch out for the size of the central rod.

I usually use a company called tick tock clocks on line for the workings and just buy a kitchen clock or something. They'll tell you if it ticks loudly. ( delivery is a bit patchy so keep on at them). They are ok but not brilliant. In truth, Ikea clocks aren't bad.

Might be a bit more than you bargained for though...get the designer to sort it out for you?

Edit. I remember seeing a clock system circuit on designs for a new Hospital that I looked over last year at the Desk Job. OMS will probably know who still makes them.

Zs

Edited: 10 August 2014 at 02:46 PM by Zs
 10 August 2014 04:31 PM
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alancapon

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I expect this is similar to the Post Office Clocks that John mentioned. There is more information on this here: http://gpoclocksystems.byethost22.com/index.html


Regards,

Alan.
 10 August 2014 04:59 PM
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John Peckham

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Alan

Thanks for that. That takes me down memory lane looking at the photo of "EIs" and the picture of my old Tool Wallet No.3 with tools. I can remember being asked on a promotion board by one of the 3 ancient interrogating engineers " why does the clock behind me go clunk every thirty seconds?". I being a cheeky young know all engineer ( same now but older) saying, "It does not sir that is a Clock 96B it is not a pulse clock it's got a shaded synchronous pole motor". I was then asked to explain how a shaded pole motor worked.

I would love a set of the old PO Engineering Instructions (EIs) for nostalgia sake if anyone knows of a source. They covered all sorts of plant and equipment in detail.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 10 August 2014 05:57 PM
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Jaymack

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This clock system was very common in industry, not only for synchronising the time throughout the buildings, but to sound the siren for meal times etc., by using the electrical wiring throughout. (No radio relay then) At one plant I had to extend this system to a new building, I used the internal telephone line system, to relay the signal to a contactor for a new clock and klaxon.

Regards
 10 August 2014 06:12 PM
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unshockable

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http://flic.kr/p/oEnHx5

And I did take a photo of the back. Thanks for the interest. The designer is actually great and hands on but didn't really know what he was buying.

Simon
 10 August 2014 06:59 PM
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Zs

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Check your PM now
 10 August 2014 07:05 PM
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sparkingchip

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That's a blow, it will be out of guarantee if you remove the cover!

Andy
 10 August 2014 07:27 PM
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AncientMariner

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If you go the route of fitting a new movement, consider using a Radio Controlled one.

You have not said what diameter your clock is, but small ones and small high torque one are easily available. (I fitted one a couple of months back).

Cheers!

Clive

-------------------------
Clive S Carver GCGI IEng MIET
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