Non-electric Television.

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Non-electric Television.

Postby Stephen » Tue Apr 10, 2007 4:08 am

Imagine a television camera and display with respective optical scanning elements driven by purely mechanical means, such as by a spring motor with a mechanical governor, just as used in old acoustical gramophones. Imagine that instead of a photoelectric sensor behind an aperture the camera uses one end of an optical fibre for light "pick-up". Imagine that instead of an electrically modulated light source the display uses the other end of the optical fibre. Assume that the optical scanning element in the display is of the lens disc or mirror drum type, that is, of the type designed to scan a modulated point of light over a display screen.

This sort of television system would then require no electricity at all for operation. Since the display uses a lens disc or mirror drum, the display transfers most of the light picked up by the end of the optical fibre in the camera to its screen.

Of course, there would be no sort of synchronisation but for the mechanical governor and possible inclusion of a clutch and/or friction brake for phasing, but it would seem possible to at least transmit bright daylight scenes some distance by such means. One could speculate that it might have been possible to demonstrate television in the late 19th century over at least a short distance using a crude optical fibre or rod as a carrier medium.
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Non-electric Television.

Postby Stephen » Tue Apr 10, 2007 4:51 am

It would also be possible to record and reproduce images non-electrically. Imagine that one end of the optical fibre extends to a photographic film strip recorder instead of a display. The end of the optical fibre then generates a variable density "video" track on the moving film strip. For reproduction, a light source such as an oil mantle lamp illuminates the developed video track on the moving film strip and one end of an optical fibre receives the modulated light. The other end of the optical fibre serves as the modulated light source in the display.

If the moving film strip is a continuous loop of film that goes through an exposure-development-resensitising process, we have a non-electrical "optical amplifier" that could allow brighter display images and/or transmission over greater distances of optical fibre. This is just a non-electric variation of the "intermediate film process" television camera used in the 1930s.
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Postby DrZarkov » Tue Apr 10, 2007 5:54 am

That is really steam-punk :D

I think this TV will have two problems: 1. The picture will be quite dark 2. running with 750 rpm the spring motor must be very big (or very short running time), so I recommend a steam-engine or a wind-mill.
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Postby Stephen » Tue Apr 10, 2007 5:59 am

The easiest solution for providing non-electric power might be by means of a water wheel--coupled to the scanning disc and mechanical governor by way of a leather belt, of course. :)
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Non Electric TV

Postby Phil Hunter » Tue Apr 10, 2007 6:31 am

How about a heat engine ? - there are rare examples of gramaphones powered this way.
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Real mechanical television.

Postby Stephen » Tue Apr 10, 2007 6:37 am

That is a great idea, Phil! I just found a link to such a gramophone with pictures at http://www.dself.dsl.pipex.com/MUSEUM/C ... ophone.htm .

Undoubtedly such a televison system with a heat engine-powered camera and display would constitute real "mechanical" television.
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Postby DrZarkov » Tue Apr 10, 2007 7:11 am

The best method would be a Stirling-engine (http://en.wikipedia.org/wiki/Stirling_engine) I think. There are small Stirling-engines available from several webshops. Not cheap, but safe ;-)
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Re non electric television

Postby Phil Hunter » Tue Apr 10, 2007 11:12 am

Irrespective of the propulsion method used (some form of gas ) would be the best method of powering the unit and of lighting it.
Before the advent of mains electricity in the UK smaller workshops were more economically powered (via the internal combustion powered "gas engine" ) as the most effective means of motive power (and subsiquent gas derived light) available.

Alas because of the relative timescales between pure steam power and steam derived electricity ( and the eventual supply of elecricity via a unified UK National Grid ) gas engines were trapped in a (relatively) narrow timescale and latgely forgotten.

I had the honour of working on the restoration of a gas supply to a (preserved) workshop powered by a gas engine in the late 1990's.

I am certain that I have some information of high power gas lighting ( using UK based "Towns Gas" ) in my archives.

I like the reference to a film medium process - just like Bairds "intermediate" system.

In the 1930's can you imagine the notion of a risk assesment (that today would have to be carried out prior to filming using Baird's intermediate 240 line system and it's cyanide derived processing bath) during the 240 / 405 line trials ?
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Non-electric Television.

Postby Stephen » Tue Apr 10, 2007 11:39 am

Optical fibres or rods were known before the 20th century and in fact were commonly used as dental illuminators. It seems that we have all the elements for a hypothetical working 19th century television system using Weiller mirror drum type optical scanning elements driven by hot air or Stirling engines powered by Towns Gas or oil connected together by glass fibre. An intermediate film process illuminated by a gas or oil mantle lamp could provide optical amplification for a longer transmission distance or a brighter display.

It would be fun to build such a system to demonstrate the principle of a completely mechanical television system.
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Postby Phil Hunter » Tue Apr 10, 2007 12:01 pm

A pure mechanical television system would be an achievement in itself . (however sucessful)
Am I correct in thinking that the optical link would be short and be direct between the (however driven) scan and recieve discs - so no sinc would be needed ?
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Postby DrZarkov » Tue Apr 10, 2007 5:14 pm

Yes, you need synch, because the glas fibre onle replaces the photo-transistor<->LED driver. The problem is that you need other ways of synchronisation. You can norm the speed of the scanning mirror, for example using a brake system like in a grammophone, but maybe controlled by a tuning fork to make it working more exactly.

A comletely different way would it be to use a lot of glas fibres, one for each pixel. That would not be very elegant, of course.
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Gas radio.

Postby Viewmaster » Tue Apr 10, 2007 6:16 pm

In the 1930's the Gas Board marketed a "Gas Radio". (An example is in the Leicester Gas Museum.)
It wasn't a true gas driven radio though.
The gas was used to heat thermocouples to generate the volts required to drive a normal valved radio.
It was quite heavy and big....it never caught on! :)
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Postby DrZarkov » Tue Apr 10, 2007 8:02 pm

In the early 20th century there was in Germany the "Flammophon", a grammophone using gas for reproducing the sound! A gas valve was controlled by the needle, the gas-flame changed, modulated by the needle. Hot air expands, so the air was directly "modulated" with sound by the changing flame.

The sound was not better than a normal grammophone, and it costs more, so this idea was not very succesful. But maybe a "club-standard" monitor would be possible with this system, the flame could be modulated by a magnet, which needs of course electricity. I wonder why nobody tried it in the age before neon-lamps.
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Postby Stephen » Tue Apr 10, 2007 11:28 pm

DrZarkov wrote:A comletely different way would it be to use a lot of glas fibres, one for each pixel. That would not be very elegant, of course.

That is what John Logie Baird suggested in his British Patent 285,738 that he filed on 15 October 1926. As you say it is not an elegant approach. I can also imagine getting tangled in hundreds of fibres whilst trying to sort them out.
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Postby DrZarkov » Tue Apr 10, 2007 11:49 pm

What did Baird not invent? :D
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