[Moog 1954] Schematics simulation and more

Posted: 2/11/2015 4:28:35 PM
riva1919

From: Italy

Joined: 2/11/2015

Hi guys!

I want to simulate the Moog 1954 schematics (http://www.thereminworld.com/Page/View/25/moog-1954-theremin-design) with OrCaD Capture (or PSpice) but I want to avoid the possibility to "reinvent the wheel again".

Is there someone that had worked on this before?

My aim is doing a frequency analysis in order to have information about theremin's harmonique and how the relation hands-antennas influence the sound.

I had already searched on the web and on this forum but I had found this article, only relative to the modern moog (or other kind of theremin):

  • Theremin circuit scratchpad: http://www.thereminworld.com/Forums/T/28789/theremin-circuits-scratchpad?Page=13
  • Best sounding theremin question: http://www.thereminworld.com/Forums/T/28567/best-sounding-theremin-question?Page=9
  • On Theremin sensitivity: http://www.thereminworld.com/Forums/T/28923/on-theremin-sensitivity
  • RCA theremin : http://www.thereminworld.com/Forums/T/28796/rca-theremin
  • Digital Theremin: http://www.thereminworld.com/Forums/T/28554/lets-design-and-build-a-mostly-digital-theremin?Page=36
  • Theremin Sounds&Acoustic: http://www.thereminworld.com/Forums/T/29093/theremin-sound-acoustics
  • Antenna non-linear relationship: http://www.thereminworld.com/Forums/T/28810/antannae-non-linear-relationship?Page=1
  • Excel theremin simulator : http://www.thereminworld.com/Forums/T/28804/excel-theremin-simulator-v4
  • Theremin pseudoscience : http://www.thereminworld.com/Forums/T/28804/excel-theremin-simulator-v4
  • Open.Theremin: http://www.thereminworld.com/Forums/T/29160/tell-us-about-your-experience-with-opentheremin?Page=2
  • Design+Development:Rules and Tools http://www.thereminworld.com/Forums/T/28786/design-development-rules-and-tools
  • "Analogue" Synthesis using LTspice: http://www.thereminworld.com/Forums/T/26458/analogue-synthesis-using-ltspice

If I have forgotten something really basic don't hesitate to tell me.

Posted: 2/11/2015 6:36:28 PM
Thierry

From: Colmar, France

Joined: 12/31/2007

From my not so modest experience, it is not really helpful to simulate theremin circuits. Since we are talking about fractions of a picoFarad when it comes to hand - antenna interaction, factors such as parasitic capacitances between components or PCB strips, the SRF of inductors, temperature dependent junction capacitances of semiconductors, etc. come into play. Respecting all that is nearly impossible in any circuit simulator.

Why not simply build the circuit and do a real-life analysis with a FFT capable oscilloscope ? That's the realistic way to get meaningful data.

Still better is collecting more experience: learn to play the theremin first and then see that you try out as many different theremin models as possible. With the years, you'll develop an intuition which will allow you to see from a schematic how a specific instrument will behave and sound. 

Theory is good, practice is better!

Posted: 2/12/2015 12:19:47 PM
Thierry

From: Colmar, France

Joined: 12/31/2007

In order to understand (and to improve) a music instrument, it is not only necessary but indispensable to study both, plans, and the instruments themselves. And that not only for current models but for the whole historic line.

That means for the theremin that you'd have to start not only with a Moog design from 1954 but with Leon Theremin's original designs from 1920. And that you'd not only to study more or less successful models (like the RCA, the Melodia, the Etherwave Pro and the tVox tour) but also the other ones, because the latter allow you to learn how one should not do things (and why!). And if you can't put your hands on one of these instruments, you may always build them from the plans. For studying purposes, it's often even not required to build the whole instrument but only the parts in which you are interested.

The following (poorly machine translated into English) German article describes how researchers of the MIT analyzed violins. You may learn from that how to proceed systematically and scientifically:

https://translate.google.com/translate?sl=de&tl=en&js=y&prev=_t&hl=fr&ie=UTF-8&u=http%3A%2F%2Fwww.spiegel.de%2Fwissenschaft%2Ftechnik%2Fgeigen-f-loecher-sorgen-fuer-vollen-klang-a-1017950.html&edit-text=&act=url

Edit:

Just found a more exhaustive research report in English :

http://rspa.royalsocietypublishing.org/content/471/2175/20140905

If every self proclaimed theremin expert would respect a similar approach, we'd have ways less crap in the theremin market.

Posted: 2/12/2015 5:05:33 PM
oldtemecula

From: 60 Miles North of San Diego, CA

Joined: 10/1/2014

riva1919 said: "If I have forgotten something really basic don't hesitate to tell me."

Most important you must have fun while exploring the different aspects of theremin design. Start from the place you are most comfortable and given enough time (years) the theremin will put you in place when needed. This will happen more than you ever expected.

I have an EWS Tube/Valve experiment (marriage) I have been working on the past month which I will share photos and sound in the next few days. There are many things I do not know but I can't let that get in my way.

Thierry seems a bit grumpy this week as maybe he is turning 50 years old soon?

Edit: No that was last June! 0-'

Good Luck

Christopher

 

Posted: 3/1/2015 5:10:04 PM
riva1919

From: Italy

Joined: 2/11/2015

[quote] In order to understand (and to improve) a music instrument, it is not only necessary but indispensable to study both, plans, and the instruments themselves. And that not only for current models but for the whole historic line.

That means for the theremin that you'd have to start not only with a Moog design from 1954 but with Leon Theremin's original designs from 1920. And that you'd not only to study more or less successful models (like the RCA, the Melodia, the Etherwave Pro and the tVox tour) but also the other ones, because the latter allow you to learn how one should not do things (and why!). And if you can't put your hands on one of these instruments, you may always build them from the plans. For studying purposes, it's often even not required to build the whole instrument but only the parts in which you are interested.

The following (poorly machine translated into English) German article describes how researchers of the MIT analyzed violins. You may learn from that how to proceed systematically and scientifically:

https://translate.google.com/translate?sl=de&tl=en&js=y&prev=_t&hl=fr&ie=UTF-8&u=http%3A%2F%2Fwww.spiegel.de%2Fwissenschaft%2Ftechnik%2Fgeigen-f-loecher-sorgen-fuer-vollen-klang-a-1017950.html&edit-text=&act=url

Edit:

Just found a more exhaustive research report in English :

http://rspa.royalsocietypublishing.org/content/471/2175/20140905

If every self proclaimed theremin expert would respect a similar approach, we'd have ways less crap in the theremin market. [/quote]

 

 

Thank Thierry and oltemecula for the interesting links and advices! 

I will follow carefully your advice but I have to insert a PSpice simulation of the 1954-Moog's theremin schematic in my thesis. So could you suggest me something more precise about previous simulation?

Thank you in advantage! 

You must be logged in to post a reply. Please log in or register for a new account.