# EM

Posted: 5/4/2015 7:41:54 PM

From: Newark

Joined: 3/18/2013

Just looking at the circuit and got lost on the PITCH TURNING so far

http://i.imgur.com/y22DG.png

http://www.theremin.info/index.php?module=-&type=file&func=get&tid=15&fid=image&pid=54

http://www.cs.nmsu.edu/~rth/EMTheremin.pdf

C10 and C11
One has 470nF going up to 12v   -   Another has 100uF going down to Ground    -   and Another has 1uF going to Ground

C12 and R14 ... 1M or 560K ... 1nF or 100pF

Volume Oscillator (Electronic Music Feb 96 to Other Diagrams)

C13 1uF to 22uF !     -     C14 2n2F to 1n8F     -     C15 10nF to 6n8F

Voltage Control Amp
R27 was 100K now 150K     -     C24 was 10nF now 3n3F

VCA

R35 was 1M8 now 4M7     -     R36 was 1M8 now 1M     -     R37 was 4M7  now 3M3

Posted: 5/4/2015 8:13:04 PM

From: Colmar, France

Joined: 12/31/2007

That's normal. The circuit has been improved over the years and it has been adapted to the (not-longer-) availability of some of the components, i.e. LM13700 vs 13600, Coilcraft SLOT TEN vs TOKO variable inductors, then improved pitch and volume range and field geometry due to a different linearization coil configuration (which induced also some slight changes in the oscillator circuits). The schematic from the theremin.info site is the most up to date, except for the linearization coils and one typo: L14 has to be 22uH...

It's an easy exercise to calculate the optimal R and C values for given components and your requirements for the pitch and volume field if you have really understood how this circuit works and what every single component does therein. In that case, you would immediately understand why it sometimes does not really matter if a capacitor goes to ground or to +12V, remember the keyword "equivalent circuit" from your electronics lessons!

(By the way, the 2x 100uF variant for C10 and C11 is the most stable one and C12-R14-R35-R36-R37 work all together and are responsible for the volume response, thus these allow you to "tail" the latter)

If you do not have that knowledge, you probably should not build a theremin from a schematic but rather go with a pre-fabricated kit.

Or you invest first some time in learning and understanding: Besides many commentaries on the web, some very skilled engineers and me too have posted lots of detailed explanations about the EM Theremin (which later became the Etherwave) and its different sub-circuit variants over the past years here. The search function of these forums is your friend!

And then, there is still the opportunity to use the free circuit simulator LTSpice (available for Windows and Mac) which allows you to draw parts or the whole circuit, varying some component values and running simulations to analyze the impact of these changes.

Posted: 5/4/2015 8:27:43 PM

From: Newark

Joined: 3/18/2013

i did electronics at college and now a electrician,

I just couldnt understand why it changed so much, and so different
I can understand touching up values and that but to change from Ground to 12v, seems a major jump

and with the internet being the way it is, some people out fake ones.
London Maps a Prim example, there are some maps with extra streets.

My main Question was, Which one was MOST up to date and were they correct as they have no Design Notes of when they were made and who did it, as i said there is a LOT of Fake things online

Dont matter ill play around with it

Posted: 5/4/2015 8:42:53 PM

From: Colmar, France

Joined: 12/31/2007

Oh, for electricians, building a theremin is difficult since for them everything above 60Hz is RF and everything below 10A is leakage current. (Old German engineer's joke) ;-)

I'd go for the schematic on theremin.info (your second link) which ist most up to date, except the aforementioned typo.

Posted: 5/4/2015 8:45:15 PM

From: 60 Miles North of San Diego, CA

Joined: 10/1/2014

Hello Angel,

I don't think Thierry mentioned above that you can buy the latest EtherWave Standard board for \$96. The main advantage of building something inferior and raw is the knowledge gained in the process. I am sure we have different goals as mine would be to develop ideas how to make the finest theremin (EWS) out there better.

The weak aspect of the EWS is the sound, otherwise it is the most solid and accepted design out there.

Christopher

Posted: 5/4/2015 8:52:04 PM

From: Colmar, France

Joined: 12/31/2007

Thank you, Christopher, I really forgot to mention it. It is true, the \$96 correspond to the billing price of 2 - 3 working hours of a qualified technician, thus you'll never build such a cheap EM/Etherwave.

Posted: 5/4/2015 10:41:26 PM

From: Newark

Joined: 3/18/2013

once made a 5v PSU for a Company i worked (i was a Design tech) when i came to testing it, i got 3.5v out.
All the maths i did and all that, dose bring in the full aspect of the 10% of how much each componet can be out.

Like a Theremin everyone is a bit different as 20nF could be 22n2F change things by 1Hz and knock on effect.

Christopher thank you

Henry by the way, i was just making a comment on how its changed from the orienal one to the NEW

If your a TEACHER or any SUPPORT on this FORM GOD HELP THE WORLD.. ANY Teacher or Parent would try and help ANY ONE to help them grow as a HUMAN.. but there are some SAD HUMAN BEANS IN THIS WORLD who just kick down any one who trys to ask a QUESTION.. you are MORE FRENCH than you are GERMAN SIR.. Please NEVER speak on some thing ive posted ever again... I do not Need INPUT that you GIVE NOR want it