The Coolidge Corner Theater Theremin

Posted: 7/20/2005 6:38:35 PM
Naveed

Joined: 7/20/2005

has anyone on this site built this theramin? i am a first time builder and decided tyo start with this simple looking design but i would appreciate some help with some of the instructions.
Posted: 7/21/2005 2:01:18 PM
Naveed

Joined: 7/20/2005

i'm asking these questions in the hopes that someone who has sucessfully built the coolidge theremin will help me.

1- what part of the 2n1264 transistor(parts q2 and q3)is the shield connection?
2- i can't find any 38" whip antennas (parts j1 and j2), would a shorter one work? and if yes, how much shorter?
3- my variable capacitors (parts c3 and c4) have three connecting pegs, but in the circuit diagram they only connect in two places, is this a problem? and if yes, what do i do about it?
4- it says to build the theremin in a metal box, but i bought some lucite instead. will this affect the performance of the instrument?

i'm sure i have more questions, but i can't think of them right now.'
Posted: 7/22/2005 12:07:38 AM
TomFarrell

From: Undisclosed location without Dick Cheney

Joined: 2/21/2005

Oh wow, I had no clue the Coolidge had any connection to Theremins, I love that theater... that's so cool.
Posted: 7/22/2005 1:28:28 PM
Naveed

Joined: 7/20/2005

thanks for the help
Posted: 7/22/2005 2:50:20 PM
Jason

From: Sammamish, Washington

Joined: 2/13/2005

Instead of whip antennas, you might try retracting antennas like the ones on a standard portable FM radio. Then you could adjust the response just by changing the antenna length.
Posted: 7/24/2005 3:09:02 PM
Naveed

Joined: 7/20/2005

thank you jason for answering one of my questions. as for the rest, does anyone here have any clue about how to build the coolidge theremin? the coolidge people haven't returned my email yet and i would like to start building my theremin soon. it's a lot of time money to spend on finding parts (and by the way, if you live in canada, radio shacks don't carry any of those parts) to not be able to build the theremin. i realise that buying the parts without knowing how to build the thing was a blunder on my part, but i would really like some help.
Posted: 7/24/2005 5:48:41 PM
user

From: Winston-Salem, NC

Joined: 6/30/2005

Y'know, I've found that getting help online works best with a little patience and a realization that nobody really has to answer questions.

Do you have a link to the circuit that you could provide?

The Etherwave is in wooden case, so I doubt that a metal case is a requirement. However, I think there is about a 3.5 inch square metal foil on the base of the case for a ground area. I'll have to look at the schematic later to be sure. From my memory, the shield connection in a transistor is a lead that connects to the metal case. There will be a 4th lead. Is there a diagram with the packaging?
Posted: 7/24/2005 9:12:27 PM
Naveed

Joined: 7/20/2005

this is the URL of the schematic;
http://www.coolidge.org/tour/theremin.html

my transistors just came in a plastic bag. i will attempt to draw the transistor here i hope it shows up well in the post.

the [ , B , and C are the labels for the wires ( the . stands for a wire) and the < is supposed to be a squarish protrusion from the side of the transistor

bottom view:
B
___
/ . \
[ |. .| C
< ___/

side view:

_____
| |
| |
---------
| | |
| | |
| | |
| | |
| | |

do you think that the wire labelled [ might be the shield connection? or the little square protrusion maybe?

also about the capacitors, it looks like two of the connecting posts are attached to the same piece of metal, do you think this means that i can just ignore the one i don't want to use?
Posted: 7/24/2005 9:14:11 PM
Naveed

Joined: 7/20/2005

sorry, those diagrams didn't show up well. the spaces inbetween things just dissapeared
Posted: 7/24/2005 10:16:03 PM
Jason

From: Sammamish, Washington

Joined: 2/13/2005

Are you sure the 2 pins on the variable capacitor are connected? Maybe you could test it with a multi-meter to be certain. Often, a 3-pin variable cap. will actually be 2 variable caps in one (see this page for an example: http://www.scitoys.com/scitoys/scitoys/radio/three_penny/three_penny.html)

Perhaps you could show us a photo of you parts so we could help you better. Maybe upload them to flickr.com or something?

I looked around tonight, and those transistors appear to to be OLD :) This happens a lot with old theremin schematics - the parts become difficult to find.

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