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Old 11th May 2018, 11:39 pm   #1
Phil G4SPZ
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Default Ferranti model 39 electric clock (1932)

Ever since I acquired a 1952 Ferranti Model 12, I've become rather fond of these well-made clocks and have been looking out for an earlier model. A recent purchase of a cheap job lot of four old clocks included this rather nice Model 39, released in 1932, together with a Model 54 from 1934. Pictures of the Model 54 will follow once I've finished repairing the (cracked) case, but it's identical apart from having a square dial. The Art Deco influence on the styling is clear.

This clock has the earlier geared movement (no worm gears like the 1952 movement) and apart from replacing the dangerous mains lead, lubricating the rotor bearings and polishing the dial, it needed very little work. The walnut case has been treated with scratch cover and a good wax polish.

I think the reliability of synchronous clocks is largely down to (a) good quality rotor bearings, and (b) a gear train that is under virtually no stress. Obviously a well-designed stator coil is part of the story too.

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Old 12th May 2018, 12:57 am   #2
Hampus
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Default Re: Ferranti model 39 electric clock (1932)

I like the style of that clock, I do have a liking for 1920 and 1930s design. It goes well with the beautiful wallpaper.
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Old 12th May 2018, 3:42 am   #3
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Default Re: Ferranti model 39 electric clock (1932)

Wow, Nice clock.

I am also very fond of mains synchronous clocks. The American ones also have the armature (to call it that) and all the small gears in one sealed housing they called "The Rotor" .The output shaft from that, often rotating at 1 rpm. But of course most of these are for 60Hz, but for many they made 50Hz versions.

I found though that I could open the rotors and just change one of the gears to correct the ratio (I had a clockmaker make the gear for me) so I could use American vintage clocks here in AU on 50Hz with a stepped down voltage. One of my favorite types from the 1930's, is the GE minutemaster cyclometer clock, I have restored 3 of these so far, photo attached. They also have an internal lamp to illuminate the drums.

The other trick, a clockmaker in the USA sells power supplies to put out the correct frequency and voltage for the particular clock. Which can be handy for clock collectors.
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Old 12th May 2018, 5:03 am   #4
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Default Re: Ferranti model 39 electric clock (1932)

I really must get round to restoring some of the shelf of electric clocks I have here..

Quote:
Originally Posted by Argus25 View Post
I am also very fond of mains synchronous clocks. The American ones also have the armature (to call it that) and all the small gears in one sealed housing they called "The Rotor" .The output shaft from that, often rotating at 1 rpm. But of course most of these are for 60Hz, but for many they made 50Hz versions.
That's often called a 'Warren' motor in the UK, after the inventor. Some years ago I bought a brand new Japanese time switch in a charity shop, it's badged 'National' (as in 'National Panasonic') and has a Warren motor to drive the dial. I'd never seen a time switch with such a motor before, but there is, of course, no reason to do it that way.
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Old 12th May 2018, 7:36 am   #5
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Default Re: Ferranti model 39 electric clock (1932)

Thanks for the info on the Warren motor. There's a bit about them here.

I've seen a different type of (smaller) geared synchronous clock motor used in things like early central heating time switches.

That Minutemaster clock is quite striking, Argus! Pardon the pun Has anyone tried running an American synchronous clock from a US-style 12V DC - to - 110V 60Hz AC inverter? The very low-power type sold for use in cars would be more than adequate, although the output waveform and frequency stability might not be good enough.
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Old 12th May 2018, 9:37 am   #6
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Default Re: Ferranti model 39 electric clock (1932)

Clock motors don't care about waveform, just as long as there is as much energy below the line as above.
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Old 12th May 2018, 9:51 am   #7
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Default Re: Ferranti model 39 electric clock (1932)

Yes, good point. I have a 150 Watt inverter, so I'll try running one of my clocks from it to see how much it gains or loses over an hour.
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Old 12th May 2018, 10:24 am   #8
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Default Re: Ferranti model 39 electric clock (1932)

Quote:
Originally Posted by TonyDuell View Post
That's often called a 'Warren' motor in the UK, after the inventor. Some years ago I bought a brand new Japanese time switch in a charity shop, it's badged 'National' (as in 'National Panasonic') and has a Warren motor to drive the dial. I'd never seen a time switch with such a motor before, but there is, of course, no reason to do it that way.
See here too for another Japanese implementation: https://lespook.files.wordpress.com/...resident-a.pdf

These Warren motors have 2-pole rotors so spin at 3000rpm on 50Hz, hence the need for the oil-encapsulated reduction gear train.
I prefer the lower-speed (200rpm) rotor approach as they're so much easier to restore.

Nice clock, Phil. These pre-war Ferrantis just go on and on. Their coils seem more reliable than those in the more compact postwar ones.

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Old 12th May 2018, 1:24 pm   #9
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Default Re: Ferranti model 39 electric clock (1932)

Quote:
Originally Posted by Phil G4SPZ View Post
Has anyone tried running an American synchronous clock from a US-style 12V DC - to - 110V 60Hz AC inverter?
The fellow in the USA who is the master of AC synchronous clocks is the Horologist, Mr Ken Reindel. He sells low power inverters to run clocks. He is also a master at mechanical clock repairs and machining clock parts:

http://www.kensclockclinic.com/catal...ise-inverters/

You should look at his website:

http://www.kensclockclinic.com/

He machined some alternate Rotor gears for me.

By the way, there is a way to run a 115V clock motor, or small transformer, from 230V without a step down transformer. (The obvious way, aside from a step-down transformer, that most people know about, is either a series resistance , or series reactance such as inductor or capacitor of the right value). However, these latter methods have to have a value of resistance or reactance suited to the exact load of the clock motor. The little known other method, I mentioned in a recent article on a computer power supply, but the genius of the method attracted little or no attention, or any remarks about it (good things get overlooked all the time). All it requires is two capacitors and a bridge rectifier and it is relatively load independent. See page 4 of this article for how this is possible:

http://www.worldphaco.com/uploads/Th...WER_SUPPLY.pdf

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Old 12th May 2018, 10:28 pm   #10
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Default Re: Ferranti model 39 electric clock (1932)

Quote:
Originally Posted by Hampus View Post
I like the style of that clock, I do have a liking for 1920s and 1930s design. It goes well with the beautiful wallpaper.
Thank you very much! Although I must give the credit for the choice of wallpaper to my wife. Sadly, her attitude towards vintage clocks is less than enthusiastic
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Old 23rd Jun 2018, 4:54 am   #11
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Default Re: Ferranti model 39 electric clock (1932)

Talking of Warren motors, I picked up one of those plug-in timer 'relays' the other day. You know, octal plug on the bottom, knob on top to set the time. I was surprised when I opened it up that it was electromechanical, not electronic. I was even more surprised when I saw it was a Warren motor (sealed aluminium housing containing the rotor and gear train with a wound stator fitted round it).
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