In January 2004 I was contacted my Scott at proverus music about building him an electro-theremin. I wasn't busy at the time, so I decided to give it a try. There were a lot of things I wanted to improve over the past Electro-Theremins I had made.
I first dug out the old Electro-Theremins, which were sitting under a shelf covered in dust. Most of the parts were also salvaged and used on other projects. So I rebuilt what I could and started testing the circuits. The main problem with the previous versions were that the circuit would "drift" in and out of tune over time. So I tried to figure out why it was doing that. I was using a cheap OPAMP function generator circuit, so I decided to design my own circuit with stability in mind.
Once the circuit was designed, I tackled the problem of "straightening out the keyboard". The problem with the other ones was also that the keyboard wasn't even. As the notes got higher, the spacing got closer. Once that was solved, I was ready to build it. I basically kept with the basic design of the 2nd prototype, only I used a few of the woodworking tricks I have learned since to make it a little bit nicer. Instead of mounting the lexan control panel directly ontop of the wood frame, I decided to use my router to make a groove around the inside of the frame for the lexan to rest. To match, I rounded off the edges of the lexan panel as well. Just as I planned on doing with prototype 2 (but never got around to it), the "keyboard" is underneath the lexan visible through a clear window area.
I also abandoned the 9V battery power supply and instead use a 12V wall-wart. For the sliding part, I used two aluminum rods (to avoid twisting). The slidey part is made of wood with a brass bushing insert. I also relocated the "momentary switch" from the control panel to right onto the slider.
In April 2004, Scott came to pick up his Electro-Theremin. He was a really nice guy and him and his girlfriend Brooke brought Hayley and I out to dinner! After that, I started a little business called "therevox" to sell these instruments.
I am now taking orders for these at Therevox.com and there is more info on the instrument there. I'm also addressing a few of the small problems in this prototype with the next prototype I'm working on. For example, the brass bushing is digging into the softer aluminum. So a bushing of UHMW plastic will be made instead. I'm also adding a switch to change the range of the instrument to increase the range of the instrument either up or down a whole octave. Increasing the range to C2-C8.
Here are some pictures of the Electro-Theremin from the "Images" section.
