Kit 17: Theremin

Yes,”Too Much Free Time and Not Enough Cash Man” is back! This time to talk about:

(Antenna cropped to concentrate on body of kit)

Gakken kit #17 – the Theremin. Lev Theremin was a physicist employed by the Russian government to develop a new kind of proximity sensor. His invention, called the Theremin, ended up playing music instead and was so popular that Lenin learned how to play it, and sent Lev on a round-trip demonstration of the machine. Lev arrived in the U.S. in 1928, took out a patent on the device, and licensed it to RCA, which produced it under the name “RCA Thereminvox”. It was released right after the market crash of 1929 and did not sell well. But it attracted the attentions of musicians globally. The Outer Limits TV show used the theremin for it’s second season title music, and soprano Loulie Norman imitated the sound of the theremin with her voice for the opening theme of the original Star Trek show. Lev himself spent time in a prison under Stalin then returned to the U.S. in 1991, where he lived until his death in 1993 at age 97. The theremin is still being sold by several companies in the U.S., including Moog ($520).

The theremin is a practical application of hetrodyning – the result of two frequencies that are slightly mismatched. You move one hand near the antenna and it causes an oscillator to change frequency. This first oscillator is compared to a second, fixed frequency oscillator, and the difference in frequencies is a sound signal that is amplified and sent to the speaker. Traditionally, the volume is controlled by how close your other hand is to the circuit ground.

Gakken has two theremin kits, the Mini ($25), and the Premium kit ($110). The Mini (#17) consists of about 10 parts, including a small pre-assembled circuit board and connected speaker, a battery holder for 4 AA cells, the antenna and the 2-piece plastic case. You assemble the case, and mount the circuit board, antenna and speaker inside. The black plastic handle is connected to the on-off switch (Off/Low Volume/High Volume). Again, the assembly is pretty straightforward. But, like the Galileo telescope, it’s not the plastic parts that make it difficult to build. This time, it’s adjusting the two oscillator sensitivity controls to get the theremin to make the right sounds when you move your hands correctly near the antenna. It takes a while to get it just right, and may require attaching aluminum foil to the battery ground post to improve the circuit’s response.

Again, the mook is the best part of the kit. There’s a biography on Lev, an interview with his daughter, photos of past performers of the instrument, and more (all in Japanese of course). There are also suggestions for customizing the kit, including stuffing it into a plush animal doll, adding a speaker jack to connect it to an external Marshall amp; modifications to the antenna; and adding 3 light sensors (photo resistors) to the side of the kit for volume control. The separate SX-150 synthesizer kit also shows a mod to run a cable so that the theremin can act as an input device to the synth.

My Mini makes some very simple noises, from a low-pitched farting up to a high-pitched squeal. Meaning that it’s only real use currently is to annoy everyone around me. And that’s good enough for me. (Note: Maybe it’s just that I still can’t tune it right. The Gakken site has a video of someone making some very nice music with one.)

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