Copper plate as antenna?

Hi, i'm new on this forum and i'd like to build the SimpleTheremin:

http://www.thereminworld.com/pics/schematics/simple.jpg

My question is:
Can i use a copper plate coming from a PCB-making blank plate to make an antenna, are there some resistance values to respect for the antennas?

I know that Zvex's Fuzz, Wah and Tremolo Probe pedal's antennas are made with a thick copper plate, but it's not really made to make sound...

Just about anything metallic will work. You may have to vary the area and/or the shape of the plate to get the response you want.

Thank you!

Hum actually my project is to put the theremin in a guitar, using a switch to use guitar's output or theremin's (because i've heard that there were some problems with EM interferences with guitar pickups, and also because it would be hard to play both instruments at the same time)

That's why i chose the SimpleTheremin design, it's the smallest i've found.
But i'm wondering about something, it's using 2 CD4093 chips to make the oscillators, but in a single CD4093 there are 4 NAND gates; is it possible to use 2 NAND gates of one CD4093 instead of 2 CD0493 with only 1 gate useful each?

That's just a matter of PCB size.. (cause those chips are 14 leads... a bit long)


Hum and i noticed that on thereminvision.com, the process is almost the same but a single CD4093 is used to make all the job (fixed and variable oscillators, mixing and even on-off switching). I will try to mix those schematics, and see what happens...

Good luck.

Maybe you could make a metal pick guard and use that as the antenna.

Hum, that's an idea, but i think the metal plate must be placed far from the pickups, behind the bridge for example... I don't really know the effects of a closer plate..

I could have used the strings as antennas, but the bridge (and so does the strings) is connected to ground (for EM shielding reasons).


For the PCB, i'll try to do a SuperSimpleTheremin, with only one chip, using 3 NAND Gates (in a CD4093).
I can't find a 20k trimpot, but i think a 25k trimmer would be ok...

Yeah, if you have to have it away form the pickups that would make it a little harder to place the thing.

Behind the bridge may be problematice because you will be close to the instrument cable and maybe the volume and tone knobs. You may be able to tune it to compensate though.

Let us know how it goes.

Okay, but take a look at this:

[img]http://frankyfuzzfire.free.fr/blackbodyzj1.jpg[/img]

The metal plate on the cutaway is a proximity sensor coming from a ZVex Wah Probe, that works with theremin effect.. and it's very close to the pickups, even if the guitar's owner (Matt Bellamy from MUSE) don't use it a lot...

First i think i'll do the circuit on my breadboard, and try different plates at different places, and see how it reacts with pickups..

I've been thinking about plates for the volume capacitor on the Tmax I'm building.... At first I was thinking of using an aluminum plate, but I recently thought that it might be easy to just cut a PC board to the shape I want. I could just solder a wire to the board on the copper side. I don't think the copper side even needs to face up. I could paint the other side some color to match the theremin case and have it facing up instead.

Parsa

Okay, but the capacitance of a capacitor is a function of it's area, thickness and material, that's why i'm a little afraid by the area it would need to have a good response with a copper sheet :s

And i think copper is the right material, more conductive than aluminium, then it could mean less material to use (speaking about volume)..

I think the dielectric effect of the air between the plate and your hand will have more influence on behavior than whether the plate is made from copper or aluminum. The tradition tube loops don't have much surface area. As long as the plate is about hand size, I think it should be OK. We're only talking about a few picofarads.

Parsa