Optical Theremin in an Altoids box
Today I finished up my Optical Theremin project.
It makes a squealing, screeching sound. The two diodes on the right detect light; as the light grows more intense, the pitch of the squealing sound goes up. You can play it by waving it around, by waving a light in front of it, by waving your hand in between it and a light, or any combination of the three. It is not particularly musical.
The switch on the bottom is an on/off switch; the nub next to it is an output jack, allowing you to plug it into an amplifier or directly into a recording device. (It has no internal speaker, so it makes no noise unless it’s plugged into something.)
Here’s what it looks like on the inside:
I used the plans on this page, with a couple of very minor modifications — for instance, I’m using a 9v battery instead of AAs so that it’ll all fit in the box, and I added the on/off switch. I’m thinking that I might add an LED (maybe to the left side) that shows when it’s turned on (since it makes no noise by itself).
The bottom of the inside of the box is coated in Plasti-Dip, as detailed here. Both the battery and the circuit board are stuck to the bottom with some double-sided scotch tape.
I am just starting out with this stuff — learning how to solder and all that. If you have any questions, feel free to leave a comment here and I’ll answer it the best I can.
March 2nd, 2008 at 5:54 pm
did you build that using the generic board? im working on the same project right now and I’m having trouble translating the schematic to be layed out on a generic board. also do you have pictures of the other side of the board? it would be nice to have as a reference as i embark on this project. thnx.
March 3rd, 2008 at 7:21 am
also, where in the circuit did you mount the switch and 1/4″ output?
March 8th, 2008 at 2:36 am
Josh, I just got back from vacation — I’ll get to this over the weekend, promise!
March 9th, 2008 at 11:31 am
thanks. im trying to finish it by tuesday so timing is key.
March 9th, 2008 at 8:09 pm
Here’s a larger version of the front (you can view or download the image to see it larger):
And here’s the back. It’s flipped top-to-bottom in the pic; left side is still left side, etc.
The on/off switch is spliced into the positive wire coming off the battery (as is the LED).
The output isn’t 1/4″, it’s a mini-phone, for size consideration. It’s connected to the thin white & blue wires in the same place that the speaker is connected in the schematic, replacing it entirely.
Feel free to ask if you have any more questions, but keep in mind that I don’t really know what I’m doing.
March 10th, 2008 at 5:45 am
thank you so much!! you have no idea how much of a help this is. as a relatively “electronics retarded” individual it makes it much easier to have something other than a schematic to reference.
May 17th, 2008 at 1:54 pm
I saw this project on the same site, and thought I’d do it for an easy electronics project. I have it out on a bred board right now… though I plan to solder it all to the pc board soon (thanks for the pictures by the way!). Did you ever have trouble getting the thing to actually do more than make a single annoying tone? Mine won’t even go silent when I completely cover the diodes. The only thing I did different from the other site is use a standard 555 timing chip that I found in our lab. Do you think that has anything to do with it? I’m sure it doesn’t, but just checking with you. Thanks for any help you can give me!
May 18th, 2008 at 5:43 pm
Yeah, I can get mine silent if I cover the diodes *completely*. Here’s a sample of how mine sounds. (I’ve added this sample to the main post as well.)
As far as the 555 chip, I have no idea — you probably know more about that than I do.
May 19th, 2008 at 10:24 am
Thanks! That’s just what I was looking for. I’m going to solder the thing together now.
May 19th, 2008 at 2:37 pm
I got it working. It turns out that I was missing one jumper which your pictures clarified for me. Thanks for posting!
August 15th, 2010 at 7:30 am
Buildings are not very cheap and not everybody is able to buy it. But, loans are created to support people in such kind of situations.
August 22nd, 2010 at 12:22 pm
Great plans, I have not had the soldering iron out in awhile.