Friday, July 8, 2011

Gakken "With KIDS" kit review

I hate it when mediafire does this. None of my images are displaying now. I sent a complaint ticket to them just now, but may not get a response back until Monday. Sorry about this.
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Gakken has been kind of shuffling its products around to improve its sales. There'd been a news release some months ago about certain children's magazines being discontinued. And it took 6 months for the entomopter kit to come out following the Theo Jansen mini-beest in January (coupled with the decision to release the entomopter instead of the Udar). On the other hand, the next kit, a second mini-beest, is tentatively scheduled for July 30.



A new kit just came out, though, called "Otona no Kagaku with KIDS" (Adult Science with kids). The mook describes various experiments you can try using sound, such as audio-driven sand art. The kit that comes with the mook is essentially a small vibration table. The base unit is a 3-leg stand with a speaker built in. The controller lets you change frequency and volume, but also has a built-in microphone for external sounds. You can put a square or round cardboard sheet on the stand, and various colored powders on the sheet. Vibrations in the stand then cause different patterns to appear in the powders. Literally, you're getting the chance to "see" sound waves.



The majority of the mook is dedicated to sound patterns, with one chapter on Ernst Chladni, the German physicist and musician that pioneered acoustic studies. Other chapters describe patterns seen on different kinds of animals, the possibility of communicating with dolphins, and sound patterns observed in the bodies of acoustic guitars. There are two suggested mods - one for modulating the kit's frequency using a piano keyboard drawn on paper in pencil, and the other for driving the kit from the audio out jack of your PC (while using some freeware software). There's also a 10-page manga highlighting the life of Japanese physicist and author Torahiko Terada.



"with KIDS" came out on June 29, for 2,100 yen ($25 USD). The book is 84 pages. The website advertises a contest for best pattern, with a Sept. 30 deadline. The kit has about 15 parts and a suggested assembly time of 30 minutes. It took me closer to 15 minutes, but I wasn't really following the instructions closely and had to take the body apart a couple of times to make corrections. The circuit board is fully assembled; no soldering and no screws. It uses 3 AA batteries. There's also a small bag of fine white sand and a salt shaker to put it in. Part of the main box doubles as the overflow tray for catching sand that falls off the sheet. You get about 10 pieces of stickyback tape for affixing different shaped sheets to the speaker. Different shapes for the sheets causes the addition of unpredictable harmonics to the patterns. The switch has three positions - Off, On and Mike On.

What is happening is that the kit normally produces a simple sinewave through the speaker that makes the sheet vibrate up and down. But, not all as one unit. The sheet is kind of like a very stiff rubber band, and you can get standing waves across the surface, depending on the frequency you choose. This results in part of the sheet going up and down at a maximum, and other parts that are more or less stationary. Sand placed over the areas of maximum vibration will be flicked off and will settle in the stationary locations. This means that the type of sand you use isn't going to affect the patterns that much. Coarser grains, like table salt, will form rougher outlines at lower volumes, while fine grains, like powder sugar, will make for much smoother lines but need the volume turned way up. In other words, it you want a nice, pretty pattern with smooth lines, use fine powders; for cruder lines, use coarser grains. Either way, the shape of the pattern will depend primarily on the frequency and sheet shape, and on volume to a lesser extent. A circular sheet will give you very simple shapes; a square gives you some harmonics because of reflections of the waves at the corners. A heart or palm-shape can introduce much more intricate patterns, but you'll have to play with the frequency control to determine the best results (which actually holds true regardless of the shape).

As for my own opinion, the frequency output starts too high. Most of the patterns I got were skewed because my table isn't sitting flat and level. I think that this kit would work much better when driven from a PC at frequencies between 20 and 200 Hz. I tried using an aluminum foil tray with water, the supplied white sand, salt and pepper. The water didn't show ripples at all, and the sand just simply wanted to escape off the tray. I got the best results with salt, and sesame seeds. I'd also like to see what would happen with a much larger disk, but it would have to be stiff and ultra lightweight to avoid bogging down the speaker.

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