The RS Optical Theremin

RS Optical Theremin

Photo-Transistor - 100% Radio Shack
(Photo courtesy of Cristian from Chile)

Here is audio Sample1 .mp3 (176k ) this is exposure to natural daylight in my well lit room. This Optical is not very musical or playable like a true theremin.

Lights will add their own type of cool distortion, here is audio Sample2 .mp3 (113k). This is my fluorescent light magnifying glass getting near the sensor.

There is no Sound in Total Darkness!
The square wave pitch rises with the light level.

The power consumption of the circuit is extremely low. If you use this circuit to drive a mini amplified computer speaker input the optical circuits "AA" batteries would last years..

If you are electronic savvy, you could enhance your optical sound using the Sixth Voice

Hello Christopher, 02.23.06

Since I haven't involved myself in an electronics project in over 10 years, I thought I'd start off with your optical theremin design since it looked far less intense than the Ultimate2B. Phase 1 was to build the optical theremin on one half of a rather large board, then phase 2 was to build the Sixth Voice on the other half and wire them together. It's unbelievable how much the Sixth Voice module improves the total sound, by the way... makes it much more musical, in my opinion.

I made one minor modification that you may or may not be interested in... The spot where you hard-wire the Optical Theremin to the Sixth Voice, I soldered in an additional 1/4" jack. What this allows me to do is plug a Y-cable into the line-out and have one cord go to the amp and the other cord go back into the Sixth Voice so it's looping back into itself. You can get some crazy effects with this, and I find it to be a very cool and beneficial, but I'm somewhat sure that most people wouldn't really find a use for it...

Anyway, here's a link to an MP3 sample and a photograph of the finished "FARTbin" -

http://www.timepromisespower.com/fartbin/

The only casing I could find that would be usable was my ArtBin paint/brush case, hence the name. Anyway, the cool thing about this case is that it's clear plastic which makes getting light onto the photo transistors really easy and is more controllable....

Anyway, thanks a bunch - now I'll be moving on to the U2B.

-dan..

Etch your own PC Board Info
or use the generic board.

Board size 1.6" x 1.8" (40mm x 45mm)

PDF (168k) <= Etch your board using this file.

Due to the increase in project e-mail, time wise I am unable to give construction support to this circuit.

. You need a black plastic sleeve around the phototransistors to block the light coming from the sides. This will make the light exposure more directional toward the phototransistors front lenses . Thanks Newbie3 When constructing make certain the electrolytic capacitor negative side is faced away from the IC. The phototransistors mount in the same direction on the board. Look for the fat internal lead C (collector)
	Value	Quan.	Part#	Price	Packs	Total	Special Notes
Q1, Q2	Phototransistor	2	276-145	1.59	2	3.18
U1	TLC555	1	276-1718	1.69	1	1.69
C1	.047 uf	1	272-1068	1.29	1	1.29	Pack has two
C2	100 uf	1	272-1044	1.29	1	1.29
R1	10 K	1	271-1335 or 271-1126	.99	1	.99	brown-black-orange-gold
R2	1 Meg	1	271-1356 or 271-1134	.99	1	.99	brown-black-green-gold

Misc.
IC Sockets	8 Pin	1	276-1995	0.69	1	0.69	Use a Socket !
PC Board	Generic	1	276-159	2.29	1	2.29	Pack has two or use PDF (168k)
V1 Battery	4 AA Holder	1	270-409	1.89	1	1.89	Switch in Battery Holder
Line Out	PC Board Term.	1	276-1388	2.29	1	xx	Optional Pack of 4
Enclosure	4x2x1	1	270-1802	2.69	1	xx	Optional Box
Prices as of Sept. 25, 2004			US Dollars	Total	=	14.30	<=Batteries Not Included (-;