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Author
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Topic: ELMO 16-CL
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David Pannell
Phenomenal Film Handler
Posts: 1072
From: Horsham, West Sussex, UK
Registered: Nov 2004
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posted February 04, 2009 06:09 AM
Here's the thing!
Trying desparately to keep my options open, whilst Jean-Marc investigates an RCA machine for me; in that I am looking for an Elmo 16-CL which I can convert to 16fps for showing silent films, of which I now have many.
Although I love using my Ampro machines for this purpose, they are somewhat noisier than the 16-CL which I already have, but it is only 24fps. There is a frequency change facility for 60Hz, but that only has the effect of running at 20fps on 50Hz mains.
My intention would be to turn down the motor pulley on a lathe to achieve the 16fps speed as a permanent set-up. I don't want to do this on my existing 16-CL as it's a fiddle to remove the rear cover with its 4 screws every time I want to change the speed.
Therefore the answer seems to be another 16-CL. It doesn't matter if the amplifier or any part of the sound system is kaput, as I wouldn't need it anyway.
SO, if anyone knows of such a machine going cheap or being thrown out, please let me know.
Many thanks in anticipation.
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Dave.
Valves and celluloid - a great combination!
Early technology rules OK!
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David Pannell
Phenomenal Film Handler
Posts: 1072
From: Horsham, West Sussex, UK
Registered: Nov 2004
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posted February 06, 2009 03:48 AM
Kevin is essentially correct.
However, it is possible to use a rheostat on an a.c. brush motor to vary the speed quite effectively - in fact that is how the speed is controlled on many older projectors, eg. Eumig P8, Elmo E-80 & F-80, Ampro Premier and Stylist models, etc. etc. It is usually achieved by inserting the rheostat in series with the armature winding which varies the current in the armature, whilst keeping the field windings constant. A contact breaker assembly is sometimes employed, again in series with the armature, as in the case of Ampros, to act as a governor, to keep the speed constant. In theory, a brush motor would run at infinite speed if it wasn't for friction, windage, losses, etc.
Kenwood mixers used the contact breaker governor method for speed control!
The advantage with a d.c. motor is that it is more controllable speed-wise, and doesn't need a governor to keep the speed constant.
The motor in the 16-CL is a synchronous induction motor, and therefore is a "frequency conscious" device. Voltage change would have little or no effect until it was reduced to such a level that it simply wouldn't run.
There are 3 ways to achieve speed change here:
1. Alter the gear ratios
2. Alter the pulley size(s) (simplest method)
3. Use a variable frequency convertor
So here I am. Looking for a spare 16-CL to alter the pulley size.
Cheers,
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Dave.
Valves and celluloid - a great combination!
Early technology rules OK!
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