BATC Forum

I'm working on a project to build a working replica of Lev Termen's 1925/26 Dal'novideniye CCTV system. I can only find very limited information about the technical design of the imager and projector. It uses a mirror-drum system and what appear to be mirror galvos, but the projector modulation method is not obvious. Does anyone have references where I might find deeper info than in Smirnov's article, where he shows two images and suggests the system was 100 lines, interlaced. I asked the copyright owner of the original image if it's possible to get a higher-resolution copy, and if she has any other photos, papers, or anecdotal info about the system, but she explained that she doesn't have anything and suggests I talk direct to Smirnov. In Russia. In 2024. Oooooo. Well, I'm on lots of lists already, hey-ho...

After Termen demonstrated it to Stalin and chums, they said "ta very much" and took the project off him so they could put it to good use, before packing him off to play the role of an international electronic instrument entrepreneur and performer, while working for the Soviet intelligence service in the USA, so the trail goes cold after that. Smirnov's article is at Smirnov_Andrey_Sound_in_Z_Experiments_i ... Russia.pdf and the photos are on P29 of the PDF.

Any information that might help in my replica project would be hugely helpful. Particularly about projector modulation techniques (Directly-modulated Carbon arc or ultra-fast voice-coil mirror galvo or whatever) and vacuum photocells with sufficiently fast responses (and high enough sensitivities) that are likely to have been available in Russia in the early 1920s

Neil G4DBN

Theremin seems to have based his approach on the use of a cylindrical mirror to improve the scanning performance of the 1907 scanning camera patent by Rosing, which was featured a few times in Scientific American during 1911. That used rotating geared polyhedral mirror drums aligned with one transverse to the lens axis and another along the axis, focussing the image on to a black plate with a small hole that then illuminated a photocell using a pool of sodium or potassium amalgam in an evacuated envelope. https://mastodon.radio/system/media_att ... b95b3d.png

Glinke's book says that Theremin used a newly-developed selenium sensor made by A N Boiko, and moved from an initial 16 line scan to 23 then 64 interlaced and finally 100 interlaced, but gives no details.

There are examples of using a voice coil, mirrors, lenses and a knife-edge to modulate light amplitude from Edison onwards, so I suspect Theremin would have followed that approach in his projector implementation, but it is only surmise on my part.