hismasters: 2100; Electric Gramophone

ID: 369512
? hismasters: 2100; Electric Gramophone 
26.Jan.15 17:24
79

Nicolaas van Dijk (CR)
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Nicolaas van Dijk

Hello all

I did upload the model and guessed that the year was 1936. There is a very similar model (If not exactly the same exept the brand) from Columbia, the magic notes 229 as indicated by the administrator, but the year of manufacturing is 1930. Is there a possibility to pinpoint the year of manufacturing a little more accurate?

Kind regards

Nico

 

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 2
Only a guess 
28.Jan.15 11:11
79 from 1685

Michael Watterson (IRL)
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Based on the design of my 1935 HMV Radiogram 370 I would have thought both the models mentioned are perhaps 1932 to 1934 era. Indirect heated mains Radios with gram input are from about 1931 in UK.

The 370 page has pictures of the motor interior, which has worm drive and adjustable speed governer.  Its moving iron pickup coil and arm is similar but very high resistance coil, extremely fine wire, about 40,000K! As the moving iron is built in, it does work with a bamboo or thorn stylus or a steel needle. The steel needles are usually single use  but still available.

Of course it might alternately be a cost reduced later version of the turntable. I have a bakelite case HMV with similar style arm and table, but different motor, it's very much later (post 1937 I think), so 1936 isn't impossible either.

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hismasters; 2100, Electric Gramophone 
28.Jan.15 13:46
93 from 1685

Nicolaas van Dijk (CR)
Articles: 43
Count of Thanks: 6
Nicolaas van Dijk

Thanks a lot for the info Michael.

The model I have does not have a governor. It is a motor with 4 coils and an anchor that seems solid iron or at least, a solid iron sleeve. That makes the motor synchroneous when the anchor magnetises. Perhaps that is the reason that there is no governor needed. So my model may be a little later than your 370 model, but again, just a guess.

Kind regards

Nico

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 4
Why a governer on a synchronous motor? 
28.Jan.15 15:38
97 from 1685

Michael Watterson (IRL)
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78 rpm is nominal. In practice maybe 65 to 85 was used? If you load a synchronous motor it "slips". Mine too is synchronous motor, but the adjustment is likely to suit the records, not mains variaton.

In these photos the lever and arm that the brass disc pushes against has been removed. As the disc slides to left it presses more on the arm (with its brake pad). The lever moves the arm position and thus the load point.

The spinning balls are on hinged springs and thus regulate the speed at point set by the moving arm (not fitted)

 

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 5
slip 
28.Jan.15 16:51
107 from 1685

Nicolaas van Dijk (CR)
Articles: 43
Count of Thanks: 4
Nicolaas van Dijk

Hello Michael

A synchroneous motor should not slip until is looses its synchronism, than it becomes an a-synchroneous motor. Therefore it needs a permanent magnet in the rotor, in my model seems done with the iron rotor sleeve that magnetizes and pulls the motor in synchronism. The RPM is 100% synchroneous with the frequency applied upto the torque where it looses. A a-synchroneus motor always slips and the slip is torque dependent. So I think that your model uses a a-synchroneaous motor.

May be interesting to see if there is a patent for the synchroneous motor, can give an idea about the year of the machine

Kind regards

Nico

 

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