For Sale: Cute 'toy' Theremins from Japan.

Greetings enthusiasts! I just wanted to drop a note here for the site, and let them know I just got in a shipment of mini 'toy' theremins from Japan. They are only $19 US, plus shipping.

I have tested one personally, and it works pretty good! It has 2 oscillator controls and one volume control. If you are curious, swing by and take a look:

Taito Thereminmin (http://www.wizzywig.com/xcart/product.php?productid=47440&cat=0&page=1)

Welcome to Theremin World, Redace.

Would that be this?

link (http://www.youtube.com/watch?v=zH7Vu9SIpVA)

It looks to have a better timbre and more playable control zone than the Gakken mini theremin, but is still a pitch only instrument, and benefits from grounding as per the Gakken.

Yes! It looks exactly like that one. And I'm curious about this grounding modification. I'll take a look around the site for that! Full report on my efforts ASAP. ^_^

OK. Some questions for your report.

What do the oscillator controls do? Do they vary the timbre of the instrument?

How large can you make the control zone (the sensitive area around the pitch rod (antenna) where sound occurs?)

As you move your hand at a slow steady pace towards the pitch rod does the pitch change slowly at first and speed up exponentially as you get closer to the rod, much as the frets on a guitar get closer together for the higher notes?

(My thought is that around this time of year people visit Theremin World who are considering buying a theremin for Christmas, but are wavering over the price. They may well be minded to invest $20 to try out on a toy to see if they take to it before potentially wasting rather more. It is sensible that they be aware of how the toy varies from a grown-up theremin.)

----

The Gakken theremin mini mod consists of trapping a strip of foil beetween the spring and the -ve end of one of the batteries and feeding it outside the enclosure so that it can be touched whilst holding the box in the non-playing hand.

Grounding theremins makes them happy, and happy toy theremins have big control zones. [img]http://b1.ac-images.myspacecdn.com/01296/11/65/1296415611_l.gif[/img]

Reporting quick test of the "Taito Thereminmin"

[b]What do the oscillator controls do? Do they vary the timbre of the instrument?[/b]

There are 3 controls in the front of the unit.

The far left one from what I see, controls the volume, and the loop on the left of the unit has no effect.

The other two buttons are marked with 1 & 2.
I started with both at top/center. The unit produced very high tones. I adjusted the center one to the right, until I heard the tone drop in pitch, until it stopped. Then, when I broguht my hand near the antenna, I got some tone variation as expected.

The far right #2 button seemed to do a similar adjustment as the #1 button, varying it from high to low pitch, and even reversing the tone from low-to-high to high-to-low, if you adjust it past the low tone spot.

I'm fairly novice to the adjustment of theremins in general, so I may be mistaking some of my adjustments. I'll post the translations from the instruction sheet when I can.

[b]How large can you make the control zone (the sensitive area around the pitch rod (antenna) where sound occurs?)[/b]

The instructions that come with it, (In Japanese, I'm getting it translated.) show the zone to be 20cm, or about 8". I could get that range fairly easily, with most effective range within about 4".

[b]As you move your hand at a slow steady pace towards the pitch rod does the pitch change slowly at first and speed up exponentially as you get closer to the rod, much as the frets on a guitar get closer together for the higher notes?[/b]

Yes, it does rise in pitch as you described above, with the rate of change speeding up as you get closer. Also, it will flip-flop to high-to-low with the settings adjusted in a certian way.

[b](My thought is that around this time of year people visit Theremin World who are considering buying a theremin for Christmas, but are wavering over the price. They may well be minded to invest $20 to try out on a toy to see if they take to it before potentially wasting rather more. It is sensible that they be aware of how the toy varies from a grown-up theremin.)[/b]

I totally agree, it's best to know the full functionality of a unit before you make an investment. I've wanted a theremin for years, for both the science of it, as well as another instrument to try to master. So when I had the opportunity to carry these at our shop, I of course had to take a chance on these. So far, I'm pleased with the performance, and I'm very novice with it, having only ever tried a "real" theremin at our local museum that had one on display.

I also tried the grounding mod. I added a copper wire to the negative spring inside the base, and ran it out the cover. I stripped several inches of wire outside, and held on to it while testing the control range. I easily extended the zone from the 8" inches to at least 12", and will try a larger foil strip when I get home and get some foil, to see my maximum range I can tweak out of it.

OK. You're adjusting it right. I don't expect broadening the foil will make much difference - the major factor is the mass of the person touching it which, for even the slightest person, is more than sufficient.

The oscillator knobs are the same as the exposed trim-pots on the Gakken.

A theremin has two oscillators, one of which has a fixed frequency and the other is variable by means of the pitch rod. Normally the frequency of the fixed oscillator is a factory preset with an internal trim, whilst the variable oscillator can be adjusted from the outside to account for objects near the theremin that affect the field.

Treat one of the knobs as the fixed oscillator (the choice is arbitrary) put it in the centre setting and forget about it unless you can't tune the other one correctly in that setting, in which case try another. (It will be useful if there is another theremin nearby operating on the same or a related wavelength, but that is all.)

I wonder if there are other similarities to the Gakken circuit. It has a distinctive feature - once the two oscillators uncouple (when the frequencies are very similar they lock together - this determines the lowest note playable - when they lock there is silence) it is possible to play lower pitches than the pitch at which uncoupling occurred. It also couples and uncouples very abruptly.

(This illustrates that - the last note is lower than the first - which meant I had no idea where it was - I just fell off the edge of the pitch cliff, so to speak. link (http://www.youtube.com/watch?v=VuHou8YpLPo))

The logarithmic response of the pitch field is no surprise. Hopefully there'll be a little area within the field that, uh, kinda approximates a straight line. A whole octave's worth would be nice. Like a toy glockenspiel. :-) That would be the "playable range" of the instrument.

For "trying out" purposes the volume control is not the main stumbling block. The first test for classical theremin playing (not, incidentally, something that I do, but never mind) is - can you hit notes accurately and move smartly between notes to give the illusion of playing two separate notes rather than a glissando. If you can do it on a tiny non-linear field I would assert that you can do it on a full sized field. The difference might be likened to playing a tiny casio keyboard, then moving to a grand piano.

(The other mod that's likely to appear is an audio out - plenty of folk out there in electronica land that take toy instruments seriously. :-)

"The Gakken theremin mini mod consists of trapping a strip of foil beetween the spring and the -ve end of one of the batteries and feeding it outside the enclosure so that it can be touched whilst holding the box in the non-playing hand."

I notice that there is a non-functional volume loop .. If this is metal, it could be used as an earth connection point - simply connect the -ve to it (ideally there is a conductive screw going into the box to which connection can be made.. but this is probably too much to hope for!)

$20? .. How does anyone produce it at that price ?!

Alas, the non-functional volume loop is silver painted plastic.

I was considering a clever mod of either gluing some foil around it and running my ground wire to that, to give it a more authentic look; or just spiral wrapping bare copper wire along it.

I'm very curious about the similarites about the Gakken's circuit and this Thereminmin model. It has a simple 4 screw assembly on the bottom. I'll take a peek inside and report back!

"I was considering a clever mod of either gluing some foil around it and running my ground wire to that, to give it a more authentic look; or just spiral wrapping bare copper wire along it."

Foil adhesive tape is great for this kind of mod - it is tougher than foil and easy to work with.. Some brands have conductive adhesive, which makes connection to the foil easier. I use this tape with all my prototype antennas.. it is easier and cheaper to use plastic pipe / trunking, and stick tape on it, than it is to bend copper! I have also used conductive (carbon loaded) paint, but this is less satisfactory.

Alright! I'm back with some show and tell.

I opened up my Thereminmin, and took some photos for your reviewing pleasure.

First up, this is the base unit, with the top cover removed. The circuit board is flipped, wtih the PCB side showing.
Base Photo. (http://www.wizzywig.com/redace/theremin5.jpg)

Next up, I freed the circut board from the base with a few more little screws, and flipped it over.

Circuit Photo. (http://www.wizzywig.com/redace/theremin3.jpg)

Here you can see that the side loop is completely fake. It's exactly 3/16", so I could probably take some brass tubing of the same size nd flare the ends, solder my grounding wire to it internally, and make it more functional. (The light blue wire you see is my ground wire that's ran through the battery cover.)

Loop Photo. (http://www.wizzywig.com/redace/theremin4.jpg)

Lastly, I scanned in the instruction pages that comes with the unit. These are higher resolution, so make take a bit longer to view.

Manual 1. (http://www.wizzywig.com/redace/theremin1.jpg)
Manual 2. (http://www.wizzywig.com/redace/theremin2.jpg)

It looks like it would be pretty easy to add an output jack to this unit, plenty of room.
Anyone have some tips on how to make a proper bybass of the internal speaker?