Circuit boffs, advise me

Posted: 6/4/2008 5:41:58 AM

From: Bristol, United Kingdom

Joined: 12/30/2006

This is part of a super secret project.

I need to know - given the technology available at the time - what would have been the smallest possible Theremin to build in the 1940s, and a rough idea of how the circuit might have looked.

Strange question, I know...
Posted: 6/4/2008 1:51:01 PM

From: Escondido, CA

Joined: 2/6/2008

I'm guessing it'd still have to be about the size of a breadbox (remember those?).

Every tube from back then was still octal socketed. The 7 and 9 pin miniature tubes came later.

You could have run the thing off of separate batteries -- that would have eliminated the power transformer.

Does that help?

Posted: 6/4/2008 4:23:36 PM
Brian R

From: Somerville, MA

Joined: 10/7/2005

If you stretch "1940s" to include the late 1940s, you could perhaps make a case for using those cutting-edge "transistors" in place of vacuum tubes... though I'm guessing the finished product would still be larger than an Etherwave.

Posted: 6/4/2008 6:43:28 PM

From: Colmar, France

Joined: 12/31/2007

Why not realize a theremin using old fashioned germanium OC71 transistors and small audio transformers?
Posted: 6/5/2008 3:47:21 AM

From: Bristol, United Kingdom

Joined: 12/30/2006

To be a bit more specific:

It's to do with a film about the Theremin, I'm soundtracking this film but also instructing actors and one of the props will have to be a Theremin, and due to the plot of the film (an act of artistic liberty that would make any Levnetter go weak at the knees) the Theremin has to be very, very small and only using parts available in Russia during the '40s. Although the size of the thing would be ample and we could simply construct a box. But it'd be nice to show some circuitry!

Thanks for the suggestions, they're really helpful. Keep 'em coming!
Posted: 6/5/2008 12:19:08 PM

From: Escondido, CA

Joined: 2/6/2008

The transistor was merely a chunk of crystal lattices "glued" together with wires tacked on in the very late 40s as indicated by Bell Labs pictures from that time period.

I'm no expert on Russian electronics, but I am pretty sure they were still using older style vacuum tubes for everything they did in the 40s.

Even in the states the transistor did not find usage until the late 1950s ... it was too unstable and unreliable :) Early missiles used very tiny vacuum tubes soldered in place. On a different note ... those tiny vacuum tubes were found to be the perfect thing to use for the preamp inside condenser mics!

I am very anxious to see this movie of yours!


Posted: 7/5/2008 2:43:36 PM

From: uk

Joined: 7/5/2008

I would go for breadbox size too. Perhaps a little smaller. Have a look at some early valve portable radios for comparison. They have tiny little valves and run on a comparatively low voltage. The battery is still the largest component though.

I'm not an expert, but schematics I've seen for valve thereminae are slightly more complicated than the average portable radio circuit.


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