The Theremin ProjectBy Al Gillis
Decades ago in a high school physics class, I built my first Theremin. This would have been in the late 1950s – well before the time of easy transistor projects! And no one had ever even heard of something called an integrated circuit!
This Theremin was quite a project, involving high voltage power supplies (nearly 300VDC), several vacuum tubes (yes, that's right) and countless other resistors and capacitors. I'd found the schematic and plans for this gadget in one of the popular magazines of the era and thought it would be an easy way to get an "A"!
The first step was to develop the layout of the physical locations of the tubes, power transformer and other major components. It seemed like weeks went by as I drilled holes in the Bud aluminum chassis! Did I ruin any of my Dad's drill bits? Most likely, but he didn't complain!
I'd ordered the components from a distributor through a local Radio TV repair shop. At first the owner of the place seemed interested in what this kid was doing, and he offered help for months, first teaching me how to read a schematic diagram and how to solder (he pointed out several times that "The Bigger the Glob – the Better the Job" was NOT an appropriate soldering technique for modern electronic equipment.)
A few days were required to sort the various components into piles that went with each stage of the construction. This idea came from the TV shop owner – a 15 year old kid doesn't know those things! Then mounting tube sockets and terminal strips, switches and pots and finally clipping the leads or resistors and capacitors and soldering them to the tube sockets and terminal strips. NO "FLYING SPLICES" ALLOWED!
Next, plug it in and turn the switch on! Hoping there would be no smoke, I went forward with troubleshooting (it didn't work the first time, of course). Pretty soon all the filaments lit up, the plate power supply was putting out the ~275 volts (Boy! That hurt if you touched it!), and it was ready for loud speakers, so I could hear the lovely music I could make by waving my hands near the antennas. Well, music wasn't exactly what one would call the sounds this new machine made! More like the squealing of an injured animal!
Quite a bit of troubleshooting at the TV shop ensued. As time passed, one of the antennas began to respond more or less as expected! I was one happy high school kid! As I recall, the second channel never made a peep. As the end of the school year was approaching, the project got put aside, never to be completed.
I had a great time making my first Theremin and learned a lot about constructing and troubleshooting electronic gadgets and made a nice career in the computer and communications industries. I even got a pretty good grade for my project based on the ingenuity and effort I put into it. Certainly not for the musical characteristics of my work!