PCB-layout for EM Theremin?

I would not use an autorouter for analog
electronics. The schematic in EM is well drawn.
If you place the components on your PCB as shown
in the schematic the routing of your traces
will be very easy. Troubleshooting is a lot
easier when the schematic and the layout match.

(* jcl *)

Well my schematics is exactly the same as in the article, just that I had to redrawn it in Eagle of course. I have my layout accordingly to the the schematics (and real life pictures I have seen). I guess I'll have to get it some more time then.
I'm good at digital electronics but unfortunately not analog. For example wrods like "earth plane" scares me of ;)
It would be much easier to make a single sided PCB for me (althought more advanced routing), but do you think a second side with an earth plane is necessary?
Thanks.

You could call it ground plane ;)

The ground plane is most likely necessary. A double
sided TH board should not be that difficult to make.
You can tolerate a fair amount of mis-alignment.

You could laminate two thin one-sided boards.

(* jcl *)

*L* yes of course, what a typo!
In Swedish the words earth and ground both have the same name ("jord") so I was too quick to translate it ;)

I'll probably go for the second suggestion, but it will take some time before I will get started.
A friend that is carpenter will make a wooden box for me for free :)






You could call it ground plane ;)

The ground plane is most likely necessary. A double
sided TH board should not be that difficult to make.
You can tolerate a fair amount of mis-alignment.

You could laminate two thin one-sided boards.

"*L* yes of course, what a typo!
In Swedish the words earth and ground both have the same name ("jord") so I was too quick to translate it ;)"

Not a typo at all! earth and ground are also synonyms here in the U.K. for most purposes.

I am not sure that having a "jord" plane on one whole side of the board is such a good idea.. There are tracks one wants to keep at as low capacitance (with respect to jord and any other sensitive or radiating tracks) as possible..

Auto-Routing? Forget it! Even the Electra gridless auto-router is not sufficiently 'good' to do a reliable Theremin layout.. UNLESS one specifies the rules etc so completely, and manually re-route tracks, taking more time than just doing a manual routing.

As with everything Theremin - I now think the JFDI approach is best (JFDI = Just * Do It).. It almost seems that performance of the theremin is inversely proportional to the theory,care, and attention to detail one spends on trying to get it right before one starts building!

Hello!

Few weeks ago i saw firt a theremin in amusic video. I decided to boult one. Unfortunately i do not know too much about electric circuits.
I was able to buy almost every parts of the theremin, but my main problem is with the leayout, and the layout diagram.
In the article it seems like to me they designed an amp inside the schematic. I thought amplifier is not necesary to design into it, since i would like to put the theremin into a keyboard amp.

I would be happy if anyone could help me to design a theremin layout diagramm.
Basicly i would like to build one like the moog, with the four knobs without gate and extras.
Simply the original Theremin one.
You can e-mail me to pintergergely@freemail.hu
Kind Regards

Korovjov

[i]"Unfortunately i do not know too much about electric circuits." - Korovjov [/i]

I would suggest that you forget about doing a layout and building a "Moog like" theremin unless you are quite competent both on electronics theory and on construction.

You say the theremin you bought (or parts) has an on-board amplifier.. Start by simply removing this amplifier and taking a line level to an external amplifier.. If you cannot easily see how to do this, then, IMHO, you really need to study some basic electronics before you even think about doing anything else!

Which Theremin did you buy / buy parts for? If it is one of the standard "jiffy bag" designs such as the SC / Jaycar' then we could probably quickly give you advice on how to remove the amp. As far as I know, no-one has released a PCB layout for Moog 'clone'.

Fred.

Well, more or less i bought the components of the moog theremin.
Here on www.thomann.de a moog theremin cost about 400 EUR. The components cost not more than 20 EUR.
I think in a factory they can produce a theremin all together about 20 EUR or less, becouse they manifacture it in a factory.
I will not pay that 400 EUR price for an instrument that i can build and do not worh more than 20 EUR.
It is not that complicated... Simply you cann ot find a perfect board layout, and components list so you could go to the store to buy them.
But! I have help, an electric engeneer who help me to build one.
So i forget your useless suggestions.
Kind Rgerads

Korovjov

Korovjov,

First, If you bought the components for the Moog EW/EM, it would NOT have an on-board power amplifier.. So you are talking BS and wasting my time.. Or you are looking at the LM13600 (LM13700) amplifier without any understanding about its function, in which case my advice in the last posting is MOST RELEVANT and you do NOT have the required understanding to build this project, with or without a PCB!

Second, You cannot buy the components for an EW for 20 EUR.. A PCB alone will cost you more than 20 EUR unless you buy in large quantities.. The pi wound inductors will cost you about 20 Euros if you get even ones inferior to those on the EW (£1.50 each * 8 - about 16 Eu) and the tunable inductors add about £3, just for starters we have already gone way over 20 Euros, without even the passives, power supply, semiconductors, hardware, antennas etc. Sure - The EW is expensive for what it is, but not outrageously expensive.

I can assure you that your statement "I think in a factory they can produce a theremin all together about 20 EUR or less" is utter bollocks - if one takes components, assembly, testing and the amortized cost of factory and equipment, It would suprise me if the total manufacturing cost of an EW was less than 100 Euros.

As for layout and component list - The EM Theremin has the list, and a wiring layout from which a PCB layout could easily be designed by anyone with basic electronics competency.. as in you would need to understand the difference between a LM13700 VCA and a power amplifier!

If you got confused and thought the LM13700 was a power amplifier, then this demonstrates that you have not even bothered to read the EM article, or the EW "hotrodding" manual - In fact, whatever you thought, it is obvious that you have not bothered to try to understand anything about the theremin - Even without english as a first language, with a little effort you could have followed enough in these articles to avoid asking stupid questions or making stupid statements!

I think it is RIGHT that a 'cloned' EW layout is NOT freely available to enable people to rip-off the EW .

Also, its Moog not "moog" - At least Bob deserves the respect of having his surname capatalized!

Fred.

Hi All

Jumping into this thread...

I am interested in building a copy of the EM theremin from the PDF of Electronic Musician (Feb 1996)

I have sourced the Toko coils in the UK but would like advice on the RF chokes. Are these still available? If not could you point me in the direction of instructions for winding suitable coils?

Lastly, the circuit board. I read in this post that it would probably work to use the component layout from Figure 4 in the article and then use the circuit diagram to manually route from point to point. I would far rather use a single sided board if at all possible. I recall reading that you should avoid large sheets of metal in the construction of theremins as these would clearly add parasitic capacitances. If this is right would the PCB really need a ground plane? did the Radio Shack prototyping board have a ground plane?

Post script regarding RF chokes. I have found the parts on Digikey. Is it correct that these chokes have ferrit cores?

Bob

Bob