Quick, simple, fun. Optical Theremin Vero layout.

[chris_d]

I found this here: http://www.oldtemecula.com/theremin/rs-opticaltheremin/rs-opticaltheremin.htm

It is probably old news, but i was looking for something to play with some infrared phototransistors and it fits the bill. The layout is dead simple and verified.



You could even make it smaller than this, but i left some space to fit the phototransistors.

Thats all. Child's play for most of you folks, but maybe fun for a noob(like me) who wants to mess with some simple light controlled theremin-ish noises. The sound is similar to the atari punk console, but the control method is more interesting, IMO.

Next up i am going to try the "Sixth Voice" project on the above page for a slightly more sine-wavey sound. If it works o.k. i'll post it too.

-chris

[$uperpuma]

fun!

[chris_d]

I have slightly revised the layout just to make the orientation of the electrolytic and photo-transistors clearer.



-chris

[gluedtogether]

Chris,
I was just fooling around with a similar circuit and was going to put a posting to see if anyone had added anything to it to enhance/add features. Let me know how the 6th voice works.

If anyone has any simple additions for this circuit, adding other controls or something interesting, let me know. Thanks

Mike

[paperhouse]

will it handle 9V?

[chris_d]

will it handle 9V?

Hmm. If you read that guy's site about SS theremin designs, he prefers the lower voltage.

What i have been doing is, i hooked up a regular 9v clip and i am using my old "dead" 6-7v (formerly 9v) batteries that i have pulled from other pedals that need more voltage than that to work right. Sort of recycling i guess.

I am not sure about the optical transistors, but everything else will take 9v fine. According to the guy who designed it, the lower voltage gives a "more musical" sound. All i can say is that the square wave this thing makes is already kind of far from what is normally considered "musical" so i am not sure that it would suffer much from the higher voltage!

-chris

[chris_d]

Chris,
I was just fooling around with a similar circuit and was going to put a posting to see if anyone had added anything to it to enhance/add features. Let me know how the 6th voice works.

If anyone has any simple additions for this circuit, adding other controls or something interesting, let me know. Thanks

Mike

Yeah, the sixth voice is an interesting idea, and i intend to build it to check it out, but i am also looking finding into various other "square to sine wave" converters. Or even just a circuit that produces a sine wave to begin with. There are a few things i am going to check out.

Light control is very cool with this sort of circuit. I retrofitted an Atari Punk Console with LDRs and it is a blast too, but these transistors are much more reactive. You can play them by producing shadow(like the LDRs), or you can get a whole other world of behavior if you hit them with a flashlight. Also, if you use a fluorescent light to agitate it you get a very different sound than you do with a regular bulb.

I spent about two hours when i built it, sitting in a dark room with strings of sound-controlled christmas lights (that blink and spin and fade in and out) with this thing sitting in the middle of the room, plugged into my guitar amp. It is very very cool, and the transistors are more sensitive than i was expecting, to available light situations.

They are very cool little buggers.

-chris

[juancra]

One little question.. Could this optical theremin be used or adapted to drive a wah as Zvex wah probe?

thanks

[paperhouse]

One little question.. Could this optical theremin be used or adapted to drive a wah as Zvex wah probe?

thanks

the photocells are optical resistors so they can be subbed for a resister in any circuit.

[chris_d]

One little question.. Could this optical theremin be used or adapted to drive a wah as Zvex wah probe?

thanks

the photocells are optical resistors so they can be subbed for a resister in any circuit.

This is true, the LDR/photocell would be better for wah adaptation than the phototransistors that are in this particular circuit.

-chris

[sevenisthenumber]

so i could put this in place of any resistor in any circuit?

[amptramp]

Lots of theremin stuff here:

http://www.theremin.us/

including an infrared theremin.

[syntaxera]

I am curious what would be the popular thought on......   

- What would you all say is the major difference between using a LDR vs. phototransistors? ( What would one expect to be different about their performance in a circuit? )

- And why in the case of this circuit are we using TWO of them over the same pins? ( Is this to catch different angles of light?  Is it for up and down controls of sorts?  or to change the resistance over all? )

[chris_d]

To be honest, i don't even remember making this thread.   

I will say that in a simple sense, functionally, i preferred the way that this build WORKED, better than  the thing i built with LDRs. It was a while ago, so i don't remember exactly, but i do remember that. It was more "theremin"-like in the way it controlled, and the way the pitches changed. Something to do with how the two builds reacted to similar light situations. This one was more useful to me at the time.

As to why it uses two transistors, i do not know. That just was the design i found, and it worked. This was a fun toy for me to play with, but i never really spent much time getting very deep into the hows and whys of it. At that time, i just wanted something odd and noisy to make odd noises with.