Etherwave mods to case and antenna

[i]I still say antenna...[/i]

even when no one is around?

One antenna, two or more antennae. Me, I like to think of the whatever it is as a gizmo to extend rather than contain the inductor's AC field (just the opposite of a "choke," which pulls the field in). So perhaps henceforth it can be an induction field extender, or IFE, or inductostender. I should also tend to think of the finger poked into the oscillating RF field as altering the dielectric properties of the medium in which the field is working, rather than as a capacitor plate. Gee, "antenna" is sounding better all the time! And if it is a rod, that's fine to call it a rod, but not if it's a tube! [I definitely don't have enough to do if I can carry on like this...]

I think the problem is that we have both electricians and musicians here.

I did high school physics. No more. I understood at the time that high school physics bears the same relationship to the real world that cartoons do. When exam questions start "Assume no friction. A car is rolling down a slope..." it does not take a genius to realise that in the real world friction is not so easily dismissed, and that if it were the car would be [i]sliding[/i] down a slope.

So, in common with most people, I have a crude understanding of electronics. In my world an antenna is a magic stick that either receives or transmits information modulated into a radio signal, and a capacitor is is a circuit component with two conductors separated by a non-conductive material, typically air. I have never heard of "radiation resistance" (*) and would not be able to apply a formula if I wanted to. Fortunately I don't need to - I'm not designing theremins, just playing them. I do need a model of how a theremin works, just as a driver will get more out of his car if he has a vague idea of how an internal combustion engine works, but a crude model is good enough. Obviously a person designing cars would need a more accurate model, but a driver doesn't.

So if I say the pitch thingie is a capacitor plate, I do so knowing that it is not that simple really, but knowing that this simplification provides sufficient information for a player to operate the theremin successfully, whereas if I stuck with the alternative explanation that it is an antenna that would not provide me with any useful understanding of my instrument whatsoever, from a musician's point of view.



(*) Well, until I encountered the term on RS Theremin's website.

RS Theremin? I'm curious about your pitch thingie design. In my simple minded high school physics way it looks either like a coil or a very long rod curled up to occupy a small space like one of those springy rubber covered antennas on walkie-talkies. Now I have read that putting coils close to the pitch thingie improved linearity - as with the ePro, and I have seen that Tony Henk's theremins have remarkably long pitch thingies (the youTube clip (http://www.youtube.com/watch?v=Xn4TgYkqdi8) of Lydia Kavina playing Clair De Lune features one.) My understanding of the inverse square law is that it can't really be defeated, other than by making the curve very large and considering only a segment of it (i.e. why the world looks flat, not spherical) or by focusing the radiation with a lens. As I don't see anything lens-like in your design would it be fair to assume that you are making a darned big EM field that approximates linearity within the playing area? (I also note that ePros require far more separation from each other to avoid interference than, say, etherwave standards.)

Good heavens, man don't take me seriously! I ended up passing out in organic chemistry (as well as the library on numerous occasions) precisely because I couldn't get the hand of physics. One of the few things that did make its way through my thick skull in physics was that an inductor (that's the coil) is the AC analogue of a resistor in DC. Much later on I read a marvellous biography of Nicola Tesla--inventor of darn near everything related to alternating current, including the tuned circuit, which pairs an inductor and a capacitor, and makes tunable radios and theremins possible, among many other things. Thanks to that book I was able to envision the interactions of alternating currents with their environments in a way I had not been able to before, and the vision is the predominant one that comes to my mind when thinking of theremins. As for whether the finger poked into the field is better thought of as altering the capacitance or the inductance is a matter for the philosophers of physics--I really don't know. But it sure does alter the fequency at which the circuit resonates!

Your observations about the Henk and EW Pro seem absolutely reasonable. If the field is extended, the area in which the rate of change of the field is closest to the geometric progression that represents the conventional musical scale (i.e. "linear") must also be bigger. Somehow they adjust that area of the field to the area where the player's [dare I say artist's?] arm is likely to be moving. Then they adjust the reference oscillator so that the difference between the two oscillating circuits is in the audio range. It's hard to say, but in the pictures I have seen of Ms Kavina playing her Henk instrument it appears that the pitch thingamabob is further from the artist than in other designs--another indication of a more extensive field, that might reasonably be expected to be less "steep" further from the thingie. Thanks for the observations, Gordon--that's something that could only be gathered from experience.

couldn't get the hand of physics
=
couldn't get the hang of physics

If it looks like an antenna, radiates like an antenna,,,,oh skip it. It's a rod, and that's good enough for me. ;)

Got an answer to my?? I can modafy the case by cuting a hole out of it and put glass in its place, but it might have to be retuned a little. Puting something metal on the controle rod it will have to be retuned as well, thats what the MOOG tech told me.There at MOOG he said they call the "rod" an antenna When the mods are done I hope to post pics!! Spook Out

I've never put a theremin under glass, or plastic, but I'd imagin that there would be some difference between the closed case, and a windowed case. I think I've seen a photo of a theremin with a window mod on the web.

GO to the Thereminworld photo gallery Misc photo page 2 very nice case looks good

So.... HOW do you call this antenna rod?