RCA Theremin Replica Made With Vintage Parts

By Jason - 5/22/2011 - Tech and DIY

YouTube user camasquil has uploaded a video of a replica 1929 RCA Theremin. According to the video notes, he used vintage era parts in the reproduction. How does it sound? Check out the video and hear for yourself!

Tags: DIY, Video, RCA Theremins

26 Comments

24 Comments

coalport 5/23/2011 7:59 AM

Impossible to tell how the RCA replica sounds because the audio (complete with birdsong and kids shouting in the background) is coming off the built-in electret mike in the camera. Also the builder of the instrument does not know how to play it!

There is a high-pitched squeal throughout the video which can be clearly heard at the beginning before the player brings the theremin volume up. I suspect this is coming from the instrument.

captain_ants 7/7/2011 5:43 PM

Hello Jason and Coalport,

I've acquired all the parts for an RCA Theremin except for the coils :) this will be a project to be attempted during Hands OFF! 2011 (http://theremin.tv). how far we get in it's construction over the long weekend I don't know but it should serve as useful learning lesson for those who are interested in how to build a Valve Theremin of their own... :)

here's a photo of one of the valves :)
[img]http://a8.sphotos.ak...[/img]

I didn't realise how massive the Valves are in these beasts until now :D

MarkT 7/8/2011 3:03 AM

Thats great work in progress Jason!

Captain Ants, drop me a line, I may be able to help you out......

captain_ants 7/8/2011 6:56 AM

Cheers Mark :)

what's your email address?

you can contact me via

office at theremin dot tv

Ants

Chobbs 7/8/2011 12:47 PM

Great project! Captain_ants- I may be able to help out with the coils.

Good Luck

captain_ants 7/8/2011 1:57 PM

Nice one Chobbs!

Coils is what we're missing :)

pictures of everything else will be posted up shortly.. :)

Cheers!

Ants

captain_ants 7/12/2011 6:15 PM

I have now added the images of the parts we have so far to the Official Hands OFF! 2011 website...

Hands OFF! 2011 RCA Theremin Project images click here (http://theremin.tv/hands-off-2011/rca-theremin-project/)

enjoy :)

captain_ants 7/12/2011 6:57 PM

by the way can anyone state for certain what the values of the six coils on an RCA Theremin are?

ie the size of each coil, along with the value of inductance.

what's the #AWG and number of turns

cheers! :)

Jeff S 7/12/2011 10:42 PM

Sure....this should get you pretty close...

RCA Theremin Component Values and Cabinet Dimensions (http://www.thereminw...)

Jason 7/12/2011 11:52 PM

Nuts... it looks like a bunch of those links are broken. I'll try to get them fixed up asap.

MarkT 7/13/2011 2:41 AM

Are those values correct? They seem different to:

RCA Coil values (http://mysite.verizon.net/arthur_harrison/RCA/rca_theremin.html)

The RCA I looked at a few years had coils on formers of 3" and 1.75"?

mikebuffington 7/13/2011 9:44 AM

Coil forms are 3" OD and small ones are 1.5" OD. Art's values are incorrect. The small coil forms from the Radiola 60 are the same size as the ones in an RCA, but the material is different. Also, the mounting locations have been changed, but the metal strip the coils are mounted to on RCAs came from the same supply as Radiola 60s, but have been modified. Close examination of both will make it clear.

Chobbs 7/13/2011 10:47 AM

What is the inductance of the second winding on the large volume antenna coil?
8 windings of #22 on a 3" form is not going to be anywhere close to the 8.9mH listed here... rca measurements (http://www.thereminworld.com/article.asp?id=27)

captain_ants 7/13/2011 6:19 PM

is there a mathamatician in the house? :D

here's a reminder of what mike did with his coils :)

http://mikebuffingto... (http://mikebuffington.net/?p=528)

how many turns is that? :)

Chobbs 7/14/2011 2:18 AM

Ha I was already trying to count the windings from his pics. looks like 8 maybe 9 if the long bit at the top(in the close up pic) is a winding and not extra to solder to the lead.

mikebuffington 7/14/2011 7:36 PM

The number 8 is ringing some bells--my theremins are on the other side of the world to me right now. The important part is that you're not supplying too much current to the 120 when it's at full volume.

captain_ants 7/26/2011 3:13 PM

Big cheers to Chobbs!

for making and posting us the Coils required for the Hands OFF! 2011 RCA Theremin project :)

Well Done Sir! :)

I shall photograph and post up the images later... but in the meanwhile I shall be raising a glass to Chobbs and his stirling achievement! :)

Thankyou! :)

Now it's up to us to try and build the thing :D

I'm sure we'll be posting up several questions during the course of the build this weekend... Looking forward to see how near we can get to completion in such a short time... but the challenge has been set and the gauntlette thrown down :)

captain_ants 8/1/2011 8:50 AM

Dan Burns of Dan Burns Theremins had a play with the soldering iron on this project. :)

images and video links to follow :)

by the way Chobbs, he was very impressed with the coils! :)

Chobbs 8/1/2011 9:45 AM

Thats good to hear...So i take it that the "RCA replica made with vintage parts" was a success.
- I was just wondering how it all turned out. Cant wait to see some images and read the wrap up.

captain_ants 8/1/2011 12:19 PM

Hello Chobbs, although we managed to have a few hours to solder the RCA we were unable to complete the task.. we will however continue to solder away over the next few weekends and cmplete the task... regular updates of course :)

mikebuffington 8/1/2011 6:39 PM

I think I spent about 70 hours over 4 days just soldering the components and wires. I was skeptical, but hopeful, that the project could be completed in a weekend.

A big question, though, I want to raise, is what are you going to do about the missing transformer in the Radiola 60 SPU?

captain_ants 8/1/2011 9:10 PM

no worries, we have a solution that will take the UK power supply :)

Chobbs 8/3/2011 6:41 PM

Any pics of the parts/ progress? Didnt see them in the hands off flickr set.

captain_ants 8/4/2011 3:48 AM

Will post up photos of the RCA Build onto the Hands OFF! website as soon as I get them.. including the images of Chobbs's wonderful Coils :)

the enclosure will be made from an old Writing cabinet :)

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RCA Theremin Replica Made With Vintage Parts

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