Question about Theremin Component

I'm studying electronics and I love the concept of the Theremin's antennae as devices to control anything - not necessarily just sound-producing oscillators.

I want to try and build the equivalent of the Pitch Antenna, simply a device that varies voltage on a circuit when one's hand moves about. How hard is that bit? Is there a circuit diagram or project somwehere to built only that part? (I've tried to be considerate of the forum and do my own searching but I haven't found much.)

Thanks for any advice you can give!
E.G.

[i]”I want to try and build the equivalent of the Pitch Antenna, simply a device that varies voltage on a circuit when one's hand moves about. How hard is that bit? Is there a circuit diagram or project somwehere to built only that part? (I've tried to be considerate of the forum and do my own searching but I haven't found much.) “ -ElGuappo[/i]

Check this thread for link to a digital module (PSoC):
http://www.thereminworld.com/forum.asp?cmd=p&T=4674&F=1

Andrey Smirnov has a web site with loads of excellent circuits for experimenters – There are voltage-output sensors given here: http://asmir.theremin.ru/tsensors_sch.htm

Then there is the Glasgow Theremin (http://www.physics.gla.ac.uk/~kskeldon/PubSci/exhibits/E9/cir2.gif) – but I strongly advise that you use the details only as a rough guide – it is not a great design IMHO.. The pitch circuit produces a voltage which appears on point ‘A’ and this voltage is amplified / shifted by the following op-amp , the (voltage) output of which drives the VCO (via a 1k).

This should do for starters.. ;-) .. I will happily give advice (my email is embedded in my icon) – I have a different way of doing the job you want to do, and will be selling a module within the next few months. At this time I cannot publish my schematic, but may be able to let you have a copy in exchange for a signed confidentiality agreement and a reasonable donation to www.streetkidsrescue.org.

Fred.

That russian link is right up my alley! He has a kit called a t-sensor which looks like just the guts I'm after. Do you know if they sell/ship those?

Thanks a lot for all the info!

e.g.

Not sure if these are available as kits - but I doubt that they are! The biggest 'problem' is getting/winding the coils.

If you want a kit, your best bet is probably to look at the low-end Silicon Chip Theremins.. The volume antenna circuit on these can be used as a voltage-output sensor - you can buy the PCB and get the needed parts seperately.

[b]{EDIT ->}[/b]I will add a link to this posting ASAP. I have a schematic somewhere showing only the required components, and will post this to E-14 (and provide a link here) ASAP. [b]{<- This has now been done - see below}[/b]The advantage of the S/C circuit is that it uses standard 455kHz I.F. Transformers, so one does not have the hassle of winding coils.

http://www.element-14.com/community/docs/DOC-24802 has schematic for CV output section of S/C / Enkelaar Theremin.

See related data for Enkelaar / EPE / S/C Theremins here:
http://www.element-14.com/community/groups/theremin-general-resources?view=documents

The best resource on the S/C Theremin is undoubtabley this on on TW :
http://www.thereminworld.com/silicon_chip_theremin_modifications.html and I advise that component values etc detailed in this article be the ones you use - also has instructions for setting the volume, which apply for setting the CV.

It is worth remembering that every Theremin with a volume antenna has a voltage (or current) output.. If you want voltage output, look at the volume circuit, not at the pitch circuit!

Fred.

Thanks for all the information, I appreciate it!

e.g.