My First Theremin - DIY

Hi mates,
I would to build a theremin, I'm looking for a valid project (this is my first time in the Theremin DIY, before I built, preampls and others audio tools, I've a good electronic knowledge). Someone could suggest me, a valid design? I've seen the etherwave design, but I don't found the PCB layout...where I can download it?
Someone in this forum, have built it?
Many thanks for your precioius help.

All the best, D.

Hi D.

There is no PCB layout for the EW that I know of.. but the full article here (http://www.element-14.com/community/docs/DOC-16870/l/build-the-em-thereminpdf) is enough to give a reasonable starting point for either building it as described in the article, or laying out a PCB yourself.

There is also the "bible (http://www.element-14.com/community/docs/DOC-16859/l/hotrodetherwavpdf)" (Hotrodding your Ew by Moog) which is the same Theremin slightly updated, and this gives a component layout which is enought basis for placing tracks and doing a layout.

Then there is the 2008 EPE Theremin for which you can buy a PCB for $18 EPE 2008 PCB (http://www.epemag3.com/index.php?option=com_virtuemart&page=shop.browse&category_id=46&Itemid=26&vmcchk=1&Itemid=26) and if you build this Theremin into a bigger (longer) box so that the antennas are futher apart, and dont wast your time with the power amp / internal speaker, can give you an excellent Theremin. (you can use the power amplifier to implement the Enkelaar modification (http://www.element-14.com/community/docs/DOC-23047/l/enkelaar-theremin-schematic) if you want to add more tone variation.

Or.. You could buy the Jaycar Theremin kit (http://www.jaycar.com.au/productView.asp?ID=KC5295) which gives you most of what you need, but modify it to turn it into something more like the EPE-2008.. The main advantage of the EPE-2008 is its improved linearity.. you need to modify the Jaycar component values for both oscillators, and add a linearizing inductor..

I would go for the EPE-2008 board out of the above options.. but a lot depends on what you want and how good at electronics you are.. If you do opt for the EPE-2008 be sure to read the articles on the subject at Element-14 theremin-general (http://www.element-14.com/community/groups/theremin-general-resources?view=documents) as there is a minor error on the PCB which can cause a headache if you dont know about it!

Also.. There are things about Theremins which designing / building audio circuits may not prepare you for!

I wish you well with your project, and there are quite a few people here ready to help you if you have questions.

Fred.

If you have some experience with valves you could go "all the way" and build a Keppinger tube thermin. Kinda a big investment, but very nice.

the etherwave/ EM is good choice if you are looking for something in the "middle of the road" between ease of building and a high quality instrument.

Hi mates,
thanks a lot for your suggestions!
Fred, sincerely I was very impressed from the EW's sound, becouse I'm a musician and I've seen much musicians to play the Etherwave Moog, but It's also much expensive (for me), so to build a good clone should to be the better solution for my pockets. :D !
About EPE, I know this interested magazine, I'm building also a magnetometer from the magazine; very affordable projects!
I could to start with the EPE, for to understand the theremin's electronic theory, and after this, to start a EW clone, with most knowledge and preparation!
Chobbs, I think that is better to discard a valve theremin, becouse I don't have much pratice with the valves, so for me is better to start with a solid state project!
In every case, I'll consider your suggestion.

Now, I'm looking for the magazine, may/june 2008, right?

Many thanks again, for your support, this is a wonderful community!

All the best, D.

Hi D,

If you can wait a week or so, email me fred[at]fundes[dot]co[dot]uk and I will see if I can copy the article for you.

Fred.

Hi Fred,
thanks a lot for your help! I've found this magazine and I've seen the project...it's a "mini theremin" right? You think that I could customize it for to build a good theremin, playable?
In this days I heard also the sound of the Lorin Edwin Parker's Theremin (http://www.youtube.com/watch?v=tys7pIyDR1Y) and I think that this sound is wondeful! So real, so expressive, so warm...it's a vacuum tube theremin!
I'm very impressed from this sound, and freezed! :) Really...the tube sound seem to be the best!
I'm in love, and confused :D !
What do you think?

All the best, D.

Chobbs, about the Mark Keppinger Theremin you was right...it's a wonderful project!
I've seen those movies (http://www.youtube.com/watch?v=CdtanoTV_Vw&p=F19BF0E88A85A207&index=1) from youtube, and it seem to be a big project, but certainly not easy!
I've seen also the
schematics (http://www.neidlinger.us/keppinger.htm) from our site....a real mission!
The sound is amazing, really.
I'm considering all the possibilities, and the costs, thanks again.

All the best, D.

[i]"I'm in love, and confused :D !"[/i]

LOL! - Confused is, I would say, the natural state when one is in love! ;-)

If you really love that particular tube Theremin sound, then you are probably better off with the EW than the EPE - The EPE could be adjusted to approach this sound, but I think the EW has more waveform distortion (due primarily to the diode mixer) and you may like it better - the EPE has a purer sine wave output (due primarily to having a true multiplier for its mixer) and even with distortions set high, probably wont get as close to the sound you want as the EW will..

It is easy enough to add the extra harmonics to the EPE.. and I do not believe there is anything a tube can do that a well designed transistor / IC circuit cannot do.. But I could be wrong!

My advice..
Build an EW or EPE - dont get too hung up about its limitations, use it as a practice run - when you have it built and working, you can play about with modifying it.. You will gain a lot of practical expierience - And if you choose to build a tube Theremin, this expierience will be worth every penny spent - And you will at least have a Theremin to play while you are building your tube Theremin!

**
The EPE is an easier Theremin to build and modify, and has buffered oscillator signals which one can do lots of things with - and makes debugging a lot easier. With the Moog circuit, the HF (oscillator) signals are at high Z.. you cannot observe them with a 'scope because the probe loads the circuit.. You cannot easily buffer the oscillator signals because the way they are coupled is part of the linearization circuit (the mixer coupling capacitors are also the oscillator coupling capacitors, and oscillator coupling has an effect on linearity at the bass end, and on wave shaping through oscillator synchronization - it is quite difficult to do anything to this section of the circuit).

The EPE 2008 has independent bufferring of the oscillator circuits, and independent oscillator coupling.. You could take the buffered outputs to a diode mixer and duplicate the Moog mixer and following circuits.. or you can take the buffered signals to a digital circuit.. As an experimental 'test bed' the EPE 2008 is almost a perfect Theremin to play with - it can drive all sorts of waveshaping and tone modification circuits.

Hi Fred,
many thanks again, now I must only to take a decision!
In those days I've found also another nice valve theremin project, please look here (http://www.ca.astro.it/web-1/Downloads/Theremin-02.pdf) and here (http://www.leradiodisophie.it/Download/prodigi_e_misteri_delle_radio.pdf) and please, tell me, what do you think.






All the best, D.

Hello D,

What can I say - ? - Part of me wants to try to talk you into picking something less ambitious, because I dont believe that tube Theremins offer any intrinsic advantage over solid state designs.. It is my view that a well designed solid state theremin will kick the c**p out of a poorly designed tube Theremin, and that a well designed tube Theremin will kick the c**p out of a poorly designed solid state Theremin - but that with equally well designed Theremins -- ? --
I cannot read the text - but the "loria" ? Theremin looks, to me, extremely similar to the Forbes Theremin design. Both the "Loria" and the "Prodigi" appear to omit any antenna equalization - to me, that is a bad sign.. I think that one of the things which makes a lot of tube theremins superior to most solid-state Theremins is the care taken over the antenna coils.

I am no expert on tubes - I was probably about 14 the last time I designed / built anything using tubes (except for CRT's and X-ray tubes.. but they dont count! ;-)

Some people believe that you dont find your Theremin, it finds you.. I think that if you believe this, its probably true.

Go for what you think you want! If you go for anything else, no matter how good it turns out, you will probably be unhappy because you will be pining for what you dont have!

Fred.