what can a theremin do?

the concept o a theremin seems awsome. can they be used to control other things besides speakers?maybe a servo in a robot or remote control plane. the possiblilities seem endless. if it is possible, how would one go about doing it?

Welcome to theremin world.

Some theremins (the Moog Etherwave Plus and the Paia Theremax kit) provide CV outs - control voltages related to the pitch and volume of the theremin sound which can be used to control non-audio equipment.

Or the audio signal from a non-CV equipped theremin could be processed in a computer using a program such as Max/MSP.

Here is a video of a theremin being used to control a video game.

http://www.youtube.com/watch?v=YnZeI8uLJnw

The Keck Telescope in Hawaii uses them to warp segments of the mirror. That is about as "far out" (heh, it's lightyears!) as you can get.

[i]"the concept o a theremin seems awsome. can they be used to control other things besides speakers?maybe a servo in a robot or remote control plane. the possiblilities seem endless. if it is possible, how would one go about doing it?" - OmegaFrenchy [/i]

First, It might help to define a "Theremin" and differentiate this from a capacitive controller..

A Theremin is a musical instrument which incorperates capacitive sensing as an integral part of the instrument - The sound generation is an integral part of the pitch sensor (pitch antenna and its circuitry) and sound is produced by beating two high frequencies together (heterodyning) to give an audio frequency, the volume sensor (volume antenna and its circuitry) form a seperate 'type' of capacitive sensor, which directly produces a control voltage used to control the volume of the audio produced by the pitch circuit.

Both the pitch and volume circuits are ideally suited to long-range capacitance sensing (about an arm length).

There are many other types of capacitive sensors, but most of these are not well suited to long range sensing. I believe that Lev Termen invented the first capacitive sensing circuit when working for the Russian secret service - the object, as I understand it, was to detect persons on the other side of a wall.. He then adapted this technology to build the first capacitively controlled musical instrument.

As other postings on this thread have stated, some Theremins output control voltages (CV's) for pitch and volume (the volume CV is available from most Theremins if one digs inside) and one can use these CV's or a volume CV and the pitch audio frequency to control extternal stuff..

[i]"..robot or remote control plane.."[/i]
I was principle Joystick engineer for PML-Flightlink (Inventors of the inductive Joystick back in the '80s.. The Flightlink joystick was created for remote control aircraft) for (too) many years.. One really needs repeatable, reliable, accurate control for critical applications - Using a Theremin to control an aircraft is likely to work out expensive! ;-) (not a problem if it is a virtual plane on a monitor ;-)

While at PML-FL, I developed a capacitive Joystick (this was a mechanical, not space-field device, but replaced the expensive coils in the inductive J/S with near-zero cost capacitive plates) but these J/S were never produced (despite being 1/4 the price) because they were deemed too risky.

[i]"how would one go about doing it?"[/i]

Depends almost entirely what you want to do. If you only want control of 2 parameters, you could use a Theremin.. If you need more than 2 parameters, you could wait for my 3d space J/S which should be on sale this year or early next.. Or you could use some of the available capsense kits on the market - for example: http://www.cypress.com/?rID=3422 If you are happier playing with digital / software .. You can make space-field Joystick using PSoC's, but it would work out quite expensive, and is not good enough (resolution / update speed) for musical applications (but should be ok for basic control of robot / model aircraft).

Fred.

For some other ways to generate a voltage from a capacitance, see http://www.thereminworld.com/forum.asp?cmd=p&T=4683&F=3

Fred.