Odd question: Pitch antenna design ...

Posted: 7/21/2012 9:47:53 PM
FredM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as WaveCrafter.com . ...................................

Joined: 12/7/2007

"Now can we agree to disagree" - Christopher

LOL! ;-) - "agree to disagree" always strikes me as a funny statement - if parties disagree, they have no civilised option but to "agree to disagree" We disagree, and thats fine - it makes life more interesting! ;-)

We are all human (I think) and IMO our individual "foibles" often obscure what we are trying to communicate - some of these "foibles" often relate to ideas we hold passionately, and in our efforts to communicate these ideas our irrational defences can make us look silly..

IMO, you were "silly" to attempt to defend your "  The theremins basic response occurs from the distance of the closest grounding mass to any part of the pitch antenna. " - As this statement was clearly wrong (if your hand is 30cm from the antenna, and someone walks up and stands 40cm from the antenna, the theremins pitch will change!) - I believe that the reason you irrationally defended the statement was the (probably erronious) idea that somehow accepting this statement as error meant relinquishing your hypothesis.

If there was another (less specific) mechanism I could use to explain the pitch / area / distance relationship, I would be happy to do so - Capacitance is not something well understood by those not "into" physics or electronics - a simple alternative descriptive way to explain things would be most welcome - but I have no idea of such a mechanism, so I cannot escape "conflict" with you, becausev I must use capacitance to explain things - even if this were to turn out to just be a useful analogy.

Neither of us will ever be "proven" to be "right" - Science does not allow that! - When it comes down to it, there may be no such thing as an "actual" theremin - they may just exist as figments of our (twisted ;-) imaginations, and we may well exist in different "universes" of our seperate minds.... But I think I am going a bit off topic.... LOL!

Fred.

Posted: 7/21/2012 11:05:12 PM
Amethyste

From: In between the Pitch and Volume hand ~ New England

Joined: 12/17/2010

RS Theremin wrote: "Fred said: IMO, you were "silly" to attempt to defend your "  The theremins basic response occurs from the distance of the closest grounding mass to any part of the pitch antenna. " - As this statement was clearly wrong (if your hand is 30cm from the antenna, and someone walks up and stands 40cm from the antenna, the theremins pitch will change!) - I believe that the reason you irrationally defended the statement was the (probably erroneous) idea that somehow accepting this statement as error meant relinquishing your hypothesis.

- As this statement was clearly wrong (if your hand is 30cm from the antenna, and someone walks up and stands 40cm from the antenna, the theremins pitch will change!) -

Not if they are behind you and if they moved closer they become the closest grounding object, seems clear to me. Basic response means just that, not every influence possible.

 

I contacted Burning Man as I think they need theremin help, they are engineers trying to pull this idea off. (-'  I have something they could use and burn, oh my. It is one of my reverse direction volume controls. I would use 20' cord for remote tuning and a LED indicator as the temperature swing will be a lot. This is the biggest concern. Then use battery power and true earth ground spike, maybe a 1/2 meter deep? This thing is already constructed, I need to set it up in my back yard and see if I can get a 8' range. In other words from dead silence gently increasing sound as you approach. Then they play what ever meditative music they want.

I might delete this as off topic.   ~Christopher"

 

Well, now you can't ;)

Posted: 7/21/2012 11:32:13 PM
coalport

From: Canada

Joined: 8/1/2008

"Agree to disagree"

I for one do not agree with "agree to disagree". No possible agreement on anything is possible in the face of disagreement! All-out WAR is the only option.

THEREWARS!

 

 

Posted: 7/22/2012 1:35:38 AM
SewerPipe

From: Flying with the Phoenix

Joined: 3/9/2011

Amey; You might go to here to see what you are suggesting, sort of. For the antenna design.

http://www.youtube.com/watch?v=wO5983mdk08

IHS ---- Dana

 

Posted: 7/22/2012 1:38:45 AM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

At Theremin frequencies (~300kHz) the wavelength is 300 x 10^6 m/s * 1/(300 x 10^3 1/s) = 1000 m.  People are on the order of 2 m, their hands much smaller.  It's hard to argue for any significant electromagnetic influence other than bulk capacitance given this.  And by saying that I'm not actually taking sides, just stating facts.  Such is the beauty of physics.

Posted: 7/22/2012 1:47:01 AM
RS Theremin

From: 60 mi. N of San Diego CA

Joined: 2/15/2005

Thanks Amey, when I first participated at TW they made fun of the way I worded sentences, as time passed they made fun of my original theories and now they make fun of my logic. I must be advancing as some still think I play word games so at times I am baffled.

Burning Man is basically an across the platform religious event with a lot of Woodstock thrown in, this was news to me. It is located about 582 miles north of me up old 395 hwy, a beautiful drive, about 133 miles north of Reno Nevada. Would I go? Only if I stayed in a nearby luxury hotel. I am to old for sunburn, smelling like a fire pit, air mattresses and no shower. Porta-Potties aren't too high on my list either.

Christopher

Posted: 7/22/2012 3:08:43 AM
Amethyste

From: In between the Pitch and Volume hand ~ New England

Joined: 12/17/2010

Christopher, you really think people here are making fun of you? I doubt that somehow... I like to think we all value each other with every little knowledge we can all share and bring to the table...

Posted: 7/22/2012 3:27:50 AM
RS Theremin

From: 60 mi. N of San Diego CA

Joined: 2/15/2005

dewster said: "At Theremin frequencies (~300kHz) the wavelength is 300 x 10^6 m/s * 1/(300 x 10^3 1/s) = 1000 m."

There is that math again that no one but an engineer would mention.

My question from the real world of pitch fields is this:

When you reach into the pitch field you break a theremin out of the Null point, what determines the maximum distance this edge of the Null point can be moved away from the pitch antenna?

I already mentioned I can get at least eight feet in open space from the tips of my fingers.

Christopher

Edit: Fred said "I, for one, am not going to waste another word on this matter."     um... that was more than two?  (-'  Were you raised Catholic or Protestant?

Fred do you want to arm wrestle?

Posted: 7/22/2012 3:28:51 AM
FredM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as WaveCrafter.com . ...................................

Joined: 12/7/2007

"Not if they are behind you and if they moved closer they become the closest grounding object, seems clear to me. Basic response means just that, not every influence possible." - Christopher

Hmmm.. Someone who is behind you is mostly "shielded" by your "capacitive shadow".. Unless they are a ghost (I have no idea about ghosts or their capacitive properties if they exist !) in order to to become the "closest grounding object" they would need to pass you on one side or the other, therebye no longer being "shielded", and therefore affecting the capacitance and theremin pitch long before they become the closest object.

I really dont understand why such an obvious fact which everyone who has ever played a theremin can demonstrate simply by switching the bloody thing on, is even being discussed or questioned! - It utterly astounds me!

I, for one, am not going to waste another word on this matter.

Fred.

Posted: 7/22/2012 3:36:41 AM
FredM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as WaveCrafter.com . ...................................

Joined: 12/7/2007

"When you reach into the pitch field you break a theremin out of the Null point, what determines the maximum distance this edge of the Null point can be moved away from the pitch antenna?"

Oscillator stability. In theory, if one had infinite stability, you could set the null point to any distance - one may only get 0.0001Hz difference frequency over a distance of 10m over some part of the "field" but it is practical electronics which is the actual limiting factor.

In terms of physics, there is no distance at which influence is reduced to zero - Much the same as there is no distance at which gravitational effects do not influence earth - However, there are influences which drop below significant or  measurable - The gravitational effects of a planet orbiting some other star are not going to bother earth much - but still exist!

Fred.

"Fred do you want to arm wrestle?"

- No thanks! - I would probably lose! ;-)

Being a pedantic AH, I must just clarify my statements on gravity - the effects of a planet orbiting a distant star will not have any effect on earth immediately - the effects will only be expierienced by earth when the waves reach earth, possibly millions of years later - much the same as an exploding star will only be observed on earth a long time after the event (fortunately - if we ever observed an exploding star less than a few years after the event, we could probably kiss our asses goodbye!)


 

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