IC Identification, help please!

[mth5044]

So I got a theremin a while ago from ebay, and I love the sound. Incase you noticed, I've been making a few threads about oscillators and ribbon controllers, so this is just another one.

I want to make this circuit for my ribbon controller, but the way they put it together makes it pretty hard to copy it. For one, the IC is glued upside down onto some kind of copper square, which looks like ground because the sleeve of the jack goes to it and all of the components are just floating above it. So I took a picture of it, and I also did my best at tracing the components to put together a schematic. Is there any way to figure out with this IC could be? It's got 14 pins. Is it just a basic oscillator? I'm guessing its also just a square wave with a filter to make it sound like a sine wave. Its such a good sound and the parts are pretty common and easy to set up.

So thanks if you can come up with anything!




It may need some explaining. The pot that is shown is like a switch also, when you turn it just a bit, the theremin turns on, then it acts as a radius dial (didn't come with directions, so this is what i call it). It determines how far the range of the antenne extends. Then halfway through the pots path, it reverses the direction of the pitch with respect to hand position. Past 12 oclock it works that the closer you get, the lower the pitch goes. There is a trim pot in there, no idea what it does. Maybe volume.

The resistor looks like it is inside the chip is just there to help keep the schematic a little cleaner. I can't seem to figure out where the power is going to the chip either.

A = antenna.

Thanks!

[Evad Nomenclature]

Are you trying to go Johnny Greenwood with the ondes/theramin type sound?
All I could think of with the theramin and ribbon controller.
Wish I could be of help, just had to comment =)

[mth5044]

I don't really like Radiohead, but I think the Ondes Martenot is freakin awesome. I think that uses a wire with a ring or something though, I'm just looking to build a ribbon controller, mainly for pitch controlling, but maybe for other things. Kind of the same idea, just not as awesome as the Martenot

[Evad Nomenclature]

Yeah...
the Ondes is pretty redonculous...
The French Connection is the one he uses... I think its a replica of the old ones... way expensive.
Badass though.
good luck!

[Paul Perry (Frostwave)]

There is at least one simple theremin circuit that uses a CD4069 (hex inverter).
The idea is, you use the inverter stages to make two oscillators - in one of the inverter oscillators, capacitance is changed by moving your hand near the 'antenna'.
I expect that three pin thing is a +5 regulator - the oscillators would be unstable enough already 

[earthtonesaudio]

Another vote for 4069.
The upper left part of the chip in the schematic looks exactly like the 2-inverter oscillator used in the Minimum Theremin.  And I'm pretty sure you have the power supply labeled backwards in the drawing, even though it looks like the builder used red for (-) and black for (+).
I would guess the trimpot is just a fine tuning control for the panel mount pot, which is a calibration control for the fixed oscillator.

The most interesting thing is that the two oscillators have been mixed through resistors and caps, rather than the usual diodes or gates.  I'm guessing it's not the most pure sine wave tone, right?

[Paul Perry (Frostwave)]

If they are 'mixed' through resistors & caps, they won't be hetrodyned at all - you need something non-linear to get the difference tone out.
Maybe there is a diode somewhere there after all!

[dschwartz]

+1 on 4069..it definetly is..check the number of pins and supply pins

[Gus]

http://www.mit.edu/~glettler/resume/undergrad/phys489_Theremaniac.pdf

http://www.physics.gla.ac.uk/~kskeldon/PubSci/exhibits/E9/

http://www.thereminworld.com/schematics.asp

http://home.att.net/~theremin1/101/101.html

[mth5044]

Alright, so I'll have to look into the 4069, thanks.

As for the power, the place where I have - power, that goes right the resistor and the resistor is soldered to the copper square. So if that's wrong, does that mean that the copper square is the + power thing? If that the case, then everything I have on that schematic going to ground, is actually going to +12v? This could be trouble.

Oh the adapter has two black wires, one with a white stripe... is the whited one stripe +? Or does that usually vary.