Old transformer Inverter thingy

[keithinuk]

Could anyone help me out with this object.

It has on it: Volts 260-250-240-230-220-210-200, Bell & Howell Co Ltd.
For use with 750 watts Projector, but on the box it says, Made in Great Britain by Kodak Ltd London

So its a voltage regulator of some type, I know of Bell & Howell, but that's no help.
I would think that its maybe 20's, 30's, but cannot find out any information on it, so far, at the moment all I know is that its a power supply for a projector, that can be regulated, I didn't know you needed to.
This is the type of item that I usually pick up, as I have no use for it what so ever, but I liked the look of it.

[keithinuk]

Once I looked up Kodak I found what looks like one, it for the KODASCOPE projector, still nice though.

[TrevorG3VLF]

I doubt if it is an inverter or regulator. I would think it is an auto transformer to set the correct voltage since bulb life is very sensitive to voltage.
If it is a regulator, it will have a saturating inductance (gets hot) and a capacitor.

[Refugee]

It looks like a rheostat to me and may well be added in series with a 110V projector.

[Tractorfan]

Hi,
It looks to me like a simple rheostat to adjust the supply to a projector running off DC mains. It would have been operated out of the case as it will get quite, if not very, hot. I imagine the slider would be set to the incoming mains voltage and the output should then be correct for the projector. Maybe it was for a travelling cinema, hence the protective case.
Just a thought.
Cheers, Pete

PS. Refugee beat me to it by a minute!

[McMurdo]

We have one (not bell & howell) for a projector. It's just a rheostat. Ours contains asbestos

[emeritus]

Yes, it does look rather like a rheostat. A traditional tungsten cine projector lamp runs at a higher temperature than a conventional GLS lamp and typically has a rated life of only 25 hours. The life of a tungsten filament varies dramatically with voltage, so possibly this is intended to ensure that the projector lamp, possibly 110V, is not over-run.

16mm movie projectors were often offered with 110V lamps where a brighter picture was required. Not only does a 110V lamp of a given wattage, output more light than a corresponding 240v lamp, but the shorter, fatter filament of a 110V lamp, being more compact than that of a corresponding 240V lamp, is a better approximation to a point source and is more efficient in an optical projection system. In the 1960's the 110V variants of Bell & Howell 16mm projectors were used with an external step-down transformer, but a transformer would not have been an option where DC mains operation was required.

[keithinuk]

Thank you for the replies, most of them were very helpful.

[McMurdo]

I think ours may be labelled 'speed'.

[mike_newcomb]

Hi,

A) am unclear why there are references above to *DC* mains, when I thought it appeared to be for AC mains. Can anyone elaborate please.

B) Are you sure it says:-

Made in Great Britain by Kodak Ltd London

or is it:-

Made in Great Britain *FOR* Kodak Ltd London

Regards - Mike

[Tractorfan]

Hi,
The reason DC was mentioned was because at the time that unit was made (possibly 20s or 30s) a lot of domestic supplies were DC. Also the supply voltage wasn't standardised as it is nowadays. Therefore, if it was for a travelling cinema, for example, then it would have to cope with the various supplies found in different parts of the county, or wherever. It would also work on AC mains if need be. The fact that it's a resistance device would point to it being used primarily on DC as well as AC. A rheostat is inefficient due to the energy wasted as heat, but at the time there was no other heap and simple way of regulating DC without going to the trouble and expense of rotary transformers and the like.
It is very similar to theatre lighting dimmers of the period which were in use up to the recent past (My secondary school had then in the late 60s!).
Hope this is useful.
Cheers, Pete

[keithinuk]

The brass label on the box has, Made in Great Britain by Kodak Ltd London W.C.2

Maybe it was made under license.
Kodak Ltd in the UK started in 1898.
Kodak used the WC2 post code from 1917 at the Kingsway London address, but the post code was originally just C.W. from 1911.

You say, domestic supplies was DC, at what voltage?

[Herald1360]

Various, depending on the supplier. 200V dc wasn't uncommon; some odd voltages were around in villages supplied by t'mill or t'pit.....

[Tractorfan]

Hi,
Indeed, as Herald 1360 says, the supply could vary from anywhere between 200 and 260volts, which is why this device was designed in the first place methinks, as it's marked in volts rather than "speed".
When electricity supplies were finally standardised as to voltage & frequency, it was possible to use the same equipment anywhere in the country without needing any regulators.
I read a fascinating article about a famous theatre organ made by Moller that used to travel throughout the UK in the 20s & 30s in several large lorries and was installed at various venues for recitals and shows. They had to carry SIX different blower motors to cope with the supplies found at each site; either AC, DC or polyphase! The current demand would have been too high for a rheostat.
Hope this is useful.
Cheers, Pete

I had an old Bell & Howell 8mm projector with a 110V bulb, on the top was a rheostat 'calibrated' from 110 to 250V. When running it was like a small electric heater.

[keithinuk]

Thanks for all your input guys, now I know what its for, its still pretty much a useless item, but that's what I seem to buy these days.

[Tractorfan]

Hi,
Maybe there's a cinematographic museum somewhere that would welcome it.
Cheers,Pete

[keithinuk]

My wife would love to have a little knick-knack museum of her own one day.
We normally collect what we like the look of and its pretty much eclectic, but we both have our own main collections.

Some of my collection.

http://www.wytewych.com/theshed.html