RCA - Signals / Waveforms etc - "Real" .

Posted: 11/17/2012 11:49:58 PM
Amp-rat

From: Connecticut, USA

Joined: 11/17/2012

Mr Chobbs, can you recommend a good transformer for the output, to allow me to use a modern speaker and/or impedance match for a modern amplifier input?  I would really appreciate any input (no pun intended). I am currently working on a 1930 Lev built unit and really want to hear it play.  

 

I was looking for a 1500:8 interstage tranny, but need a little guidance.

 

TIA,

Andrew

https://picasaweb.google.com/lh/photo/bs1BPxbJgx5fiiES1su2NeKuPbc9xo-mXlfH6N6t1Og?feat=directlink

Posted: 11/18/2012 3:33:12 PM
Chobbs

From: Brooklyn,NY

Joined: 12/1/2009

Hey Andrew,

Wow! that looks like a fun project.  That is one true historical artifact-  'It belongs in a museum'   (to quote Dr. Jones)  Amazing - Where/ how did you get it?

I got some used tx's at oldradioparts.com-  have a look. it is incredibly cheap but kinda overwhelming also there is a $25 minimum. You'll have to make a list and email him to see what he has in stock.   Im pretty sure it is just 1 old guy and acres of parts in boxes. it may take a few days to hear back.    great supplier, though... especially  if you are getting a bucket load stuff. 

Also check out this hammond output tx.  I think it'll do the trick.

If you are interested,  I have a 'spare' RCA 106 loudspeaker  (no cabinet) I may be convinced to part with - especially if it'll be paired with such a special instrument.   Good luck- Please document and share your progress with this project.

 

 

Posted: 11/19/2012 1:37:49 AM
Amp-rat

From: Connecticut, USA

Joined: 11/17/2012

Customer received it from family estate, had been in storage for ~60 years.  They brought it in on a whim when they had their Korg M1 serviced*.  The unit as received would not power up. 

I immediately realised it was special, and with some internet research, and several phone conversations have determined that it was most likely built by Lev Theremin himself.

I have a custom cabinet maker that I use for special jobs, I would love to work a deal for your rca 106, it would be so preferable to have the correct speaker with the instrument.

Back in High School, I cut my teeth on restoring and repairing vintage AM radio's,from the 20's ~ 50's.  This is the neatest piece I've seen in years.

Photo's are here: https://picasaweb.google.com/bellaudiolab/ThereminElectronics?authuser=0&authkey=Gv1sRgCNvG3dnc-5OmmAE&feat=directlink

 

*I own and operate Bell Audio Lab, LLC.  www.bellaudiolab.com  if you'd like to look me up.

 

 

 

 

Posted: 11/19/2012 2:01:57 AM
Chobbs

From: Brooklyn,NY

Joined: 12/1/2009

Ill say it again..... 'wow, looks like a fun project' 

Im totally jealous. That is something special.     I love the no-chassis design.

  The osc coils look like RCA's.  Id love to see a schematic, if you can get the chance to draw one up.    also measure inductance!

Posted: 11/19/2012 7:36:40 AM
FredM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as WaveCrafter.com . ...................................

Joined: 12/7/2007

Yeah -

That looks like an extremely exciting project!

I (and I am sure most people here) would love to follow your progress on this - I personally would love to see schematics and component values (particularly coil inductances) and snapshots of the waveforms into and out of the mixer..

Welcome to TW, Amp-Rat .. Thats certainly a grand enterence you have made!

A few of us here have probably gone a slight shade of green!

;-)

Fred.

Posted: 11/22/2012 1:09:42 AM
Amp-rat

From: Connecticut, USA

Joined: 11/17/2012

Fred, if you shoot me a email address I will send you the measurement in a pdf file.

Posted: 11/22/2012 1:26:44 AM
Chobbs

From: Brooklyn,NY

Joined: 12/1/2009

post them here!

Posted: 11/22/2012 5:19:07 AM
Jason

From: Sammamish, Washington

Joined: 2/13/2005

Certainly.  It would be a wonderful service to the Theremin community to document the details of this rare find. If you'd like to mail us and docs, we can post them on the site for you.

Posted: 11/22/2012 5:34:51 AM
w0ttm

From: Small town Missouri on Rt 66

Joined: 2/27/2011

WOW!!!!!!!!!!!!

I sure does look like a Lev built, and in great shape to boot!

This is the most exciting thing I've seen in a very long time. Maybe ever.

I have a few vintage parts. Please post what you need.

Posted: 11/22/2012 12:53:19 PM
FredM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as WaveCrafter.com . ...................................

Joined: 12/7/2007

"Fred, if you shoot me a email address I will send you the measurement in a pdf file."

<---------------- See top of my avatar   ( fred [the_symbol_at]  fundes  [_a_dot_] co [ _a_dot_] uk )  

Thanks "Amp-Rat" ;-)

My email is embedded at the top of my picture (Avatar)

>> Edit: Ignore what I say in the following.. I was talking ignorant nonsense!

"I sure does look like a Lev built, and in great shape to boot!" - w0ttm

Im no expert - but I think the clincher will be if anything Lev ever built was done in that chassis-less style.. I think this is unusual (something which was mostly done by hobbyists who never had access to metal punching tools) -

I know that back in those days (well - certainly in the '60's) plywood was the hobbyists circuit board - easy to cut holes in, and brass wood screws served as tagging points to solder components onto if one couldnt afford tag board (in fact, nails were my favorite - wrap some TCW round them and when soldered they made a great mounting post - and cheaper than brass screws!)..

Not sure if this applies elsewhere in the world - but in SA at that time, stuff like tag board and new tube sockets were expensive.. Almost everything I used was salvaged or improvised from what I could get for peanuts - and everything built was done with access to only basic tools.

Whatever - Lev built or not, the excitement remains..

You must be logged in to post a reply. Please log in or register for a new account.