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 synthesizer kit also shows a mod to run a cable so that the theremin can act as an input device to the synth. Most mods require soldering in wires and I don't have a soldering iron yet.
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. So far, I can only get mine to fart and squeal.)

Also on the slate this time is
Kit #1, the Putt Putt Boat. These kinds of boats have been around for years, and there are a number of vids on Youtube showing how to make your own out of plastic soda bottles or sheets of tin. So, it's not like Gakken is giving us anything really new here in the very first kit from this series. It's also a fairly simple kit, with a one-piece plastic body for the boat, 3 pontoons, a candle tray, holder and 4 candles, and the steam chamber. The science behind this kind of boat is very straight-forward. A small amount of water is placed in one tube of the engine to prime it, and then a candle is lit and placed under the steam chamber. Steam builds up in the chamber and the pressure expels it out the other tube, pushing the boat forward. More water flows into the chamber from the primed tube and the process repeats until the candle burns out. As long as the boat is in the water, it creates a closed circuit for the water flow.
The problem is that this kind of boat isn't designed for being used outdoors. I tried launching it from the nearby river, and the couple-mile-an-hour wind put out the candle, and the 1-2 inch tall waves swamped the boat and soaked the wick. At best, I need a perfectly calm day, or to use an indoor pool or bath tub. The candle is tiny, so it'll only burn for a few minutes, too. Which makes it kind of silly to have a small hole in one fin of the boat for tying a thread to it for hauling the boat back if it gets too far out from shore. It may be possible to use a slightly larger candle, though, to make it run longer (the size of the engine limits how big a candle you can use). The mook suggests taking foil to make a tray, pour in salt, add whiskey and then light the whiskey. But the wind again blew out the flame. I'm wondering what would happen if I used sugar instead of salt... Maybe if I can find a quiet pond to work from...
But, the real value from this kit is in the mook. Published in 2003, it is interesting on multiple levels. First, it's the first of the series, and shows how Gakken initially thought the series would run (mostly by including ideas for cheap DIY science projects). Second, it contains a photographic history of 40 years of science toys for kids, most or all of which had come from Gakken. Third, this mook is a treasure trove of mods for other Gakken Adult Science kits, including the Edison speaker amp, and has a circuit for the 150 block electronics kit to make a theremin. Finally, there's a series of science experiments for performing magic and bar tricks, such as smoke from your fingertips, and how to make a ping pong ball stick to the bottom of a bottle of water. I may try translating the manga at the back, showing a rivalry between Edison and the inventor of the first flat-disk record player
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I need to make a final comment. I've mentioned previously that these kits in the Adult Science mook series range between $20 and $85. That's not correct. The first 10 or so volumes are priced at 1600 to 1800 yen, including the one selling on Amazon for 8500 yen. Most are currently selling for 2500 to 3500 yen because of the collector's value. Volume 1 is now going for 2300 to 3000 yen online, but I found a copy at a bookstore and picked it up for the original 1680 yen, including tax. Volume 2, the fingerprinting kit, is the one least in demand, and sometimes can be found online for 600 yen. Otherwise, all the others have been appreciating in value, assuming that the packaging hasn't been opened and the kit assembled (defeats the purpose of having the kit, unless you get two copies of each). The one most in demand is the steam engine car, priced at 1600 yen and now selling for 8500 yen. I'd really like to find a copy in a bookstore, but the odds of that are low to none, I'm afraid.
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It also turns out that part of the mooks are available online.
Volume 1Volume 17