For Sale: Cute 'toy' Theremins from Japan.

Well, that ain't no Gakken inside.

This is what I love about small businesses - you wouldn't get this from a chain store.

Haha. I just got off the phone from a British sole proprietor, successfully negotiating to buy his shop doorbell!

(OK, not your average doorbell - actually an Alesis AirFX (a thereminesque device discontinued a few years ago and the very last one he had) which he has been using [i]as[/i] a shop doorbell.)

I'll leave the electronics to our electronics guys.

Hello redace,

What an outstanding piece of research you have followed through on. What country are you in, the theremin shipped from where and what was your shipping cost?

If it is $19 usd, every theremin designer out there is drooling over the cost effective possibilities of using this board. (Parts on a pre-made board) Looking at your board photo it appears to use heterodyning so it should sound much better with a little experimenting. Definitely the speaker hurts the performance. The real treasure I see is modifying it into an inexpensive universal theremin RF volume control hoop.

For your question:

“Anyone have some tips on how to make a proper bypass of the internal speaker?”

Unsolder the speaker wires, replace with a 1/4” jack and plug in a cable to a keyboard amplifier and hopefully the audio-out pot control will let you set the proper level low enough to drive a guitar amp.

Christopher
.

[b]What an outstanding piece of research you have followed through on.[/b]
Glad to be of service! Being a fan of the theremin myself, I have quite the self interest as well.
[b]What country are you in, the theremin shipped from where and what was your shipping cost?[/b]

I'm in Ann Arbor, Michigan, USA. We ship within the USA via UPS, via your choice of service, from ground to next day air. Starts at around $10 for ground. For overseas shipments we use United States Postal Service, priority mail. For a typical example, to ship to the UK, I'd expect the shipping costs to run from $26-29USD for 1 or 2 pounds.

(We got in a full case of these, and have around 70 pieces left.)

Some first impressions...

Delivery to the UK took two weeks. So if you're a Brit and you order now it will arrive just after Christmas. Very well packaged and still as light as a feather.

Fitting the four AAA batteries (not included) requires a size 1 Philips Head screwdriver. (That's the largest one in my kit of tiny screwdrivers.)

The tuning is fiddly. It took me about 5 minutes to achieve a 20cm control zone. I have not tried earthing (grounding) it yet.

Touching any part of the black casing (but not the faux volume loop) affects the tuning.

The timbre is "wasp in a jam-jar" and the range is small.

It occurs to me that if you wanted to modify it, rather than drilling through the case one could simply remove the volume loop, which leaves two convenient holes. The holes are about the right sort of size to accommodate a 3.5mm mono jack socket, but I have not tried it or done accurate measurements.

Thank you for the excellent photos!

From what I can see, it looks like it does indeed have two discrete-transistor oscillators that are heterodyned.

The 8-pin DIP IC is probably an opamp or IC power amp.

As for disconnecting the speaker, you might want to use a "closed-circuit" jack. Connect the speaker to the switch terminal (if you look closely you will see a terminal that is touching the tip terminal without a plug inserted, and is pushed away from it when a plug is inserted ... that is the switch terminal) and the wire that used to go to the speaker to the tip terminal. Connect a wire from the other speaker terminal to the "sleeve" terminal.

With this arrangement you can still use the internal speaker when it is not practical to run it through and external audio amp.

Don

Never could get mine to work right...the control range is 6" max.

[i]Never could get mine to work right...the control range is 6" max.[/i]


I payed 360 US$ for my Etherwave... that makes 15US$ per 1" pitch range...

I think you have paid less than 90 US$ for your 6", so don't complain... ;-)

That 6" range is easily extended! The unit grounding tip works wonders for this unit. Just wrap a bit of wire around the ground spring and hold a stripped bit of it while playing. (I used a spare strand of CAT5 cable.) Also, when you adjust the oscillator controls, don't take it all the way to the lock gap, back it up a little bit, until you have a low tone. I've found that it senses your hand close by while adjusting, and thus will give you a "false" gap point.
Now when you move your hand away, you'll find the tone will drop off much farther out. I got mine up to at least 12" with decent tone. If you adjust it up even higher, I noticed you can affect the tone, (albiet very slightly due to the non linear ramp), from a couple of feet away.

All in all, this thing seems like the perfect starting point for someone who wants to "hack at" a theremin design.

There's all sorts of experiments to do:
1. Try a different cabinet
2. Try a tune-circuit (variable capacitor, fixed-inductor) in series with the antenna.
3. Try to make a volume loop control out of a second one.

This is the sort of thing the professors ought to toss at their students for term-end projects.

Don

I just picked up the Taito Thereminmin but i'm having trouble getting it to work and wondering if anyone has suggestions.
I have knob #1 set at the halfway point and have tried adjusting the #2 knob up and down. I can only find one setting where the theremin isn't constantly making noise but will react to my hand by the wire. But my hand has to get within an inch and a half.
I haven't tried the foil idea to extend the range yet.