building a pseudo-tannerin/theremin

[cedric]

so if i went ahead and made a square wave outputtin'-machine (using a 555 - yeah i've read through colin's site ), how will i be able to control the pitch by using a piece of metal/copper, and by touching it?
making a different note on the different lenghts of the metal plate.

- ced

[Tim Escobedo]

http://www.geocities.com/tpe123/folkurban/synthstick/synthstick.html

Beware, resistive videotape is getting harder to find.

[Steve C]

FYI, Bob Moog is supposed to be on the Tech TV channel 3-16-04 at 7pm talking about the theremin and some other stuff.

[Bucksears]

A little OT, but did anyone catch 'The Simpsons' last night?
There are creepy squarewave noises coming from the attic and Homer, heading for the attic, gets mad and says "THAT'S it. You can scare my kids all you want, but you will NOT play my Theremin!"

[Paul Perry (Frostwave)]

For simplicity, it is hard to beat a pot wiht a handle attached!!
and for smoother action, a RC oscillator with a tuning capacitor (the old radfio type, if you get a 3 gang one, you can get over 1000pf, which is enough, I have also seen phase shift audio oscillators using 2 gangs of a radio receiver condenser.

[Mark Hammer]

Yeah that WAS a good Simpson's episode, and a joy to see theremins get respect.

Very odd instruments to play.  Harry Bissell brought his quantized MIDIfied theremin over about a year and a half ago.  It plays scales rather than a continuous pitch but you have to go through every note on the way to any other note.  A bit like trying to play the piano by rolling an orange around without ever taking your hand off the orange or keyboard.  Remember that gestural controllers like theremins don't allow for random access to notes the way that  keyboards or guitars do.  Take your hand off a keyboard and it doesn't do anything until you strike another key.  Move your hand near a theremin, and it still thinks the music's going and interprets your hand movement as a control voltage source.

Ribbon controllers can be a bit different I suppose, in that you can always enable the control voltage from the ribbon with one hand while you move the pointer/contact with the other.  Tricky, but feasible.  I've never heard of anyone using something like, say, a foot-controller to enable/disable the derived control voltage from a theremin so that you could make interval jumps.

I got a note from Tom Polk about 4 years ago, concerning the Tannerin I had seen the Beach Boys use in 1970 or so.  I don't know the precise material it used for the ribbon controller but it was a conductive ribbon.  Mike Love had the notes of "Good Vibrations" marked off in White-out or something similar so that he could see where to move the pointer/contact in dim lighting.

There are a variety of conductive materials that could serve as resistive elements for a ribbon controller.  Videotape is one as is traditional brown audio tape.  I imagine the conductive mylar bags one gets components in would be another.  All it really needs to be is flexible and conductive.  The actual resistance of the voltage divider formed is something you can design around.

Another possibility is that you etch yourself a board with pads emerging from a resistive ladder (think of a comb where 49 100R resistors form the spine of the comb and pads branching out from their junctions form the comb's "teeth") and use a stylus controller.  A number of "keyboard" projects over the years have used such a control method.  The standard arrangement is to use a volts-per-octave division system and fixed intervals, but there is no reason why you couldn't aim for something a little more chromatic.

Another possibility is to borrow a page from the Ernie Ball Volume Pedal and traditional FM tuners and use a cable/pulley system to move a rotary element like a pot.  This would let you translate the limited rotation of a pot into a larger/broader range of movement so that you could be more precise.

[cedric]

thank you. all of you.
forgot about the synthsitck - i'll prolly go down that route actually.

but how many octaves will it go through? cause being the size of an altoids tin can doesn't excactly make it the biggest instrument known to man

[Tim Escobedo]

There are a couple other ideas to implement a unorthodox electronic musical instrument. A couple I've done were inspired by a old device called the Blacet Syn-Bow (tiny picture at bottom). Unfortunately, Blacet no longer has any docs covering the device, and even if you had a schem, it uses unobtanium to do it's sonic stuff. However, it's form factor is easily adapted to many other designs. One I made used a simple touch switch  to gate the on-board oscillator, and the "wand" controlled frequency. Another one used a rather dodgy mechanism which allowed the "wand" to move in two axes. (Holding it like a guitar) Up/down controlled frequency, and in/out controlled pulse width from 0% to about 50% (in practical use), which changes vol/timbre at the same time. I tried doing similar things using a old joystick(which moves in two axes easily), with more easily obtained results.

This was a couple years back. I recently got some surplus analog force sensors that I've been thinking on using in a newer version to output a CV (and thus a VCF/VCA), and the "wand" to control freq (or even output a different CV).

This might be a easier lead, considering how difficult it's getting to find resistive videotape.

but how many octaves will it go through? cause being the size of an altoids tin can doesn't excactly make it the biggest instrument known to man

I find the useability of range depends on the length of the ribbon controller.  At about 1m in length, I find it has a useable range of about 2 octaves. Keep in mind that it's a (somewhat) linear resistance, so the notes get "closer together" as you play in higher range. Very much like the frets on a guitar!

The oscillator, on the other hand, can be tuned to any audio range (and beyond).