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'[OT] Theremins'
2005\11\29@052759 by Bill & Pookie

picon face
Had to Google Theremins to refresh my memory.  Moog is making them now for
about $350.00 USD.

http://www.zzounds.com/item--BIGETHERWAVE

Looks like a great PIC project, "Pic Theremins"
Or Pic Theremins/Proximenty Detector".

Breaking and entering put to music.

Bill

{Original Message removed}

2005\11\29@071750 by David Van Horn

picon face


> -----Original Message-----
> From: spam_OUTpiclist-bouncesTakeThisOuTspammit.edu [.....piclist-bouncesKILLspamspam@spam@mit.edu] On
Behalf
> Of Bill & Pookie
> Sent: Tuesday, November 29, 2005 6:01 AM
> To: pic microcontroller discussion list
> Subject: [OT] Theremins
>
> Had to Google Theremins to refresh my memory.  Moog is making them now
for
> about $350.00 USD.

The etherwave is one of a few serious instruments out there.
Bob died recently. :(

> http://www.zzounds.com/item--BIGETHERWAVE
>
> Looks like a great PIC project, "Pic Theremins"
> Or Pic Theremins/Proximenty Detector".

If it doesn't do both pitch and volume, it's a noisemaker.
The pitch "antenna" tuning is quite a bit more interesting than you'd
think.



2005\11\29@071750 by David Van Horn

picon face


> -----Original Message-----
> From: piclist-bouncesspamKILLspammit.edu [.....piclist-bouncesKILLspamspam.....mit.edu] On
Behalf
> Of Bill & Pookie
> Sent: Tuesday, November 29, 2005 6:01 AM
> To: pic microcontroller discussion list
> Subject: [OT] Theremins
>
> Had to Google Theremins to refresh my memory.  Moog is making them now
for
> about $350.00 USD.

The etherwave is one of a few serious instruments out there.
Bob died recently. :(

> http://www.zzounds.com/item--BIGETHERWAVE
>
> Looks like a great PIC project, "Pic Theremins"
> Or Pic Theremins/Proximenty Detector".

If it doesn't do both pitch and volume, it's a noisemaker.
The pitch "antenna" tuning is quite a bit more interesting than you'd
think.



2005\11\30@063215 by Howard Winter

face
flavicon
picon face
David,

On Tue, 29 Nov 2005 07:26:13 -0500, David Van Horn wrote:

{Quote hidden}

I've always loved Theremins - but I've never managed to find one to have a go, but I understand the Science
Museum in London has one, so I may have to go and find out!  In one of the Back to the Future films there's
one just standing there in the professor's junkroom - it's never referred to, just standing there as a prop.  
Shame!

Someone did do a PIC-Theremin project in EPE magazine a couple of years ago, but it had a potentiometer as the
volume control, and I thought that was a copout (wasn't even a sliding pot, as I remember!).

The famous Beach Boys' use of a Theremin in "Good Vibrations" is dodgy too - seeing the film of them doing it,
the pitch control is done using a sliding shorting bar on a pair of rails, which makes it just a VFO in my
opinion, not a real Theremin.

Cheers,


Howard Winter
St.Albans, England


2005\11\30@070048 by Wouter van Ooijen

face picon face
> Theremin

Fay Lovsky is a dutch artist who occasionaly plays a theremin.
http://www.lovsky.com/theremin/

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


2005\11\30@070255 by Bill & Pookie

picon face
Was thinking of using cadium sulfide cells (light resistors) in place of
radio waves on a pic.

Bill

----- Original Message -----
From: "Howard Winter" <@spam@HDRWKILLspamspamH2Org.demon.co.uk>
To: "Microcontroller discussion list - Public." <KILLspampiclistKILLspamspammit.edu>
Sent: Wednesday, November 30, 2005 3:32 AM
Subject: RE: [OT] Theremins


> David,
>
> On Tue, 29 Nov 2005 07:26:13 -0500, David Van Horn wrote:
>
>> > {Original Message removed}

2005\11\30@075503 by Alan B. Pearce

face picon face
>Was thinking of using cadium sulfide cells (light
>resistors) in place of radio waves on a pic.

I seem to remember Popular Electronics, or one of the other "Popular xxx"
American magazines, doing a Theremin using Cds cells back in the 1960s.

2005\11\30@080745 by Howard Winter

face
flavicon
picon face
On Wed, 30 Nov 2005 13:02:49 +0100, Wouter van Ooijen
wrote:

> > Theremin
>
> Fay Lovsky is a dutch artist who occasionaly plays a
theremin.
> http://www.lovsky.com/theremin/

LOL!  I love her "Theremins through the ages" pictures!

Cheers,


Howard Winter
St.Albans, England


2005\11\30@085333 by Lindy Mayfield

flavicon
face
I've thought this to be a nice project, too, but I still get lost in the electronics part.

How would you generate the output wave?  Would you generate a BTC series of bits?  I was thinking once that somehow I could use a VCO, but I got hopelessly confused when searching for VCO's.  I didn't realize that there was such a range of frequencies.

Then I got sidetracked by trying to think how I could create a cell phone jammer to use when people get out-of-hand loud on the bus.  Then I moved to Finland and all my toys are still packed up.

Fun to still think about this stuff, though. (-:

Lindy

-----Original Message-----
From: RemoveMEpiclist-bouncesTakeThisOuTspamMIT.EDU [spamBeGonepiclist-bouncesspamBeGonespamMIT.EDU] On Behalf Of Bill & Pookie
Sent: Wednesday, November 30, 2005 2:03 PM
To: Microcontroller discussion list - Public.
Subject: Re: [OT] Theremins

Was thinking of using cadium sulfide cells (light resistors) in place of
radio waves on a pic.

Bill



2005\11\30@092646 by David Van Horn

picon face
> Someone did do a PIC-Theremin project in EPE magazine a couple of
years
> ago, but it had a potentiometer as the
> volume control, and I thought that was a copout (wasn't even a sliding
> pot, as I remember!).

The volume side is the least understood by most people.
A fixed oscillator is run through a filter circuit, which the "antenna"
is part of. Your hand capacitance varies the center of that passband.
The RF that passes through the filter is detected, and the level then
sets the volume through a VCA.

The pitch side though, is where the "magic" happens.  There is a tuned
circuit on the "antenna" which is hard to explain in simple terms. It's
SRF is VERY close to the operating frequency, which amplifies and
linearizes the pitch scale, but only if properly tuned.  It's far more
complicated than just a body capacitance tuned VCO.

> The famous Beach Boys' use of a Theremin in "Good Vibrations" is dodgy
too
> - seeing the film of them doing it,
> the pitch control is done using a sliding shorting bar on a pair of
rails,
> which makes it just a VFO in my
> opinion, not a real Theremin.

It's a theremin variant.



2005\11\30@092851 by David Van Horn

picon face


> -----Original Message-----
> From: TakeThisOuTpiclist-bouncesEraseMEspamspam_OUTmit.edu [RemoveMEpiclist-bouncesspamTakeThisOuTmit.edu] On
Behalf
> Of Wouter van Ooijen
> Sent: Wednesday, November 30, 2005 7:46 AM
> To: 'Microcontroller discussion list - Public.'
> Subject: RE: [OT] Theremins
>
> > Theremin
>
> Fay Lovsky is a dutch artist who occasionaly plays a theremin.
> http://www.lovsky.com/theremin/

The next to last is even funnier, Stalin did actually play one, at least
once.



2005\11\30@094358 by olin piclist

face picon face
David Van Horn wrote:
>> Fay Lovsky is a dutch artist who occasionaly plays a theremin.
>> http://www.lovsky.com/theremin/
>
> The next to last is even funnier, Stalin did actually play one, at least
> once.

Except that looks more like a statue of Lenin to me.

******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2005\11\30@105825 by David Van Horn

picon face
> > The next to last is even funnier, Stalin did actually play one, at
least
> > once.
>
> Except that looks more like a statue of Lenin to me.

Probably is.


2005\11\30@131016 by Vitaliy

flavicon
face
David Van Horn wrote:
>> > The next to last is even funnier, Stalin did actually play one, at
> least
>> > once.
>>
>> Except that looks more like a statue of Lenin to me.
>
> Probably is.

If this is what you guys are talking about:

http://www.lovsky.com/theremin/target5.html

I can confirm that it is indeed a statue of Lenin. I've actually read a
story many years ago about Theremin's visit to Lenin to demonstrate the
device. Wikipedia has something to say on this subject:

http://en.wikipedia.org/wiki/Theremin#History

Theremin also demonstrated a "human presence" detector, which would set off
an alarm if someone got too close to the antennas.

Best regards,

Vitaliy

2005\11\30@134658 by David Van Horn

picon face
> http://www.lovsky.com/theremin/target5.html
>
> I can confirm that it is indeed a statue of Lenin. I've actually read
a
> story many years ago about Theremin's visit to Lenin to demonstrate
the
> device. Wikipedia has something to say on this subject:
>
> http://en.wikipedia.org/wiki/Theremin#History

Sorry, I had it backwards, it was Lenin.
Check in Glinsky's book



2005\11\30@134828 by Lindy Mayfield

flavicon
face
Is it something like two frequencies together produce frequencies which are both the sum and the difference between the two inputs?  And they go through a low pass filter to get the final tone? Like tuning a guitar the closer you get to tuning two strings the faster the beat gets?  Or is that how it might be done now?



{Original Message removed}

2005\11\30@134938 by Lindy Mayfield

flavicon
face
Even with the training wheels on their Theremin, I've heard that they set some sort of record at the time on the number of takes it took to get that song right.  That could just be anecdotal, though.  

{Original Message removed}

2005\11\30@140852 by Lindy Mayfield

flavicon
face
Since the file name of the pic is therem-len-in.jpg
(-:

-----Original Message-----
From: piclist-bouncesEraseMEspam.....mit.edu [EraseMEpiclist-bouncesspammit.edu] On Behalf Of David Van Horn
Sent: 30. marraskuuta 2005 18:07
To: Microcontroller discussion list - Public.
Subject: RE: [OT] Theremins

> > The next to last is even funnier, Stalin did actually play one, at
least
> > once.
>
> Except that looks more like a statue of Lenin to me.

Probably is.


2005\11\30@145909 by David Van Horn

picon face
> Is it something like two frequencies together produce frequencies
which
> are both the sum and the difference between the two inputs?  And they
go
> through a low pass filter to get the final tone? Like tuning a guitar
the
> closer you get to tuning two strings the faster the beat gets?  Or is
that
> how it might be done now?

For getting the pitch itself, you use a pair of oscillators, like
700kHz-ish.  They sit maybe 200 Hz apart at idle more or less. So the
mix products would be 700200, and 200 hz.

What I was talking about there though, is what separates a real playable
instrument, from a noisemaker.

Original RCA design:
http://home.att.net/~theremin1/RCA/rca_theremin.html

I have a short writeup on it here for a more modern instrument:
http://www.dvanhorn.org/Theremin/AntennaTuning.php

Some more data here:
http://www.dogstar.dantimax.dk/theremin/thersens.htm


With the Theremax, the antenna coils were pretty much ignored, and it
wasn't clear to me how they should be designed from the information that
I've found  on the web.


I've been able to measure out what the Etherwave pitch antenna is, using
my
Tek 7L5 spectrum analyzer, and again the Theremin proves to have
surprisingly complex behavior.


I'm sure this applies to most Theremin designs, as they all seem to have
the  basic structure of a parallel resonant tank circuit in the pitch
osc, and a series LC network in the antenna. I'm sure that some don't
take advantage of the behavior that I've noticed here, to their apparent
disadvantage.


Conventionally measuring the antenna circuit proves to be difficult,
because even the input impedance of a Tek scope probe is way beyond the
effects that  are produced by operating the instrument normally.
Attaching the probe drastically detunes the circuit. Still, with special
techniques, it is possible to examine the circuit, relatively
non-intrusively.  As it turns out, the spectrum analyzer is only needed
when you don't already know how to look for this effect, or what causes
it.


Background:


The antenna and it's loading coils form a series resonant circuit at
some frequency.
I had thought, and now confirmed using the Etherwave, that the behavior
of the pitch control would be affected significantly by how the pitch
osc is tuned relative to the series resonant point (SRP) of the antenna
system.


Most Theremin circuits that I have seen have the same basic structure.
They have a parallel resonant tank circuit in the pitch oscillator, and
the antenna and antenna coil form a series resonant circuit.


The parallel resonant pair presents maximum impedance, nearly purely
resistive, at it's resonant point.  If the antenna circuit was dead on
resonant at the same frequency, then it would also present some level of
purely resistive impedance.


The interesting thing, is that the antenna circuit presents it's lowest
impedance at resonance, and the tank circuit presents it's highest
impedance at resonance. So, the oscillator cannot function properly (if
at all), if both circuits are tuned to, or nearly to, the same
frequency.


What happens:


The behavior of the pitch oscillator is very interesting when tuned near
the antenna resonant point.  Starting at the lowest frequency, it moves
smoothly up through it's range, then takes a sudden jump of about
10-20kHz when we cross the antenna resonant point. Due to the
interactions, the resonant point is somewhat indistinct, but we can
locate it closely enough to improve the system performance.


Since the pitch oscillator becomes unstable at the point where it hits
the antenna resonant frequency, this obviously would be a catastrophic
place to tune your pitch oscillator to. :)


So, you get to choose whether to place your pitch oscillator above or
below the antenna resonant point. So, I investigated where the range is,
relative to this point.  I found that which side you select, and exactly
where you select, makes a distinct difference.


I tried a number of points, starting about 30kHz below the resonant
point, and ending about 30kHz above the resonant point. Beyond these
points, the difference diminishes rapidly, until you have very similar
control behavior above, or below the resonant point of the antenna
system.


With the oscillator tuned just below the antenna resonance, the control
range is somewhat compressed. The closer you get to the antenna
resonance, the more compressed it becomes.(!)  With the oscillator just
above the resonance, the control range is expanded.
The closer you get to the antenna resonant point, the more expanded the
control range becomes.


This makes some sense to me from an antenna tuning/tesla coil
perspective.
On the low side (pitch osc below antenna resonance), the antenna is
slightly capacitive. A given increase in your hand capacitance lowers
the self resonant point of the antenna, which makes it LESS capacitive,
so the tuning range becomes compressed.  On the high side, the antenna
is slightly inductive, so you make it less inductive and more capacitive
as you approach the antenna. These two changes add to each other, and
this explains the expanded range.  Different antenna and coil designs
will react to different degrees, but the basics should hold.


It seems that the shift in the antenna self resonant frequency works in
conjunction with the hand capacitance, but only if you are on the high
side of the antenna's self resonant point, and fairly close to that
point


The coils in the Etherwave are still a compromise, being physically very
small, and having a lot of parasitic capacitance.  I'll be looking at
that soon.


This behavior near the antenna resonance may also explain some squirrely
behavior that I saw when first setting up the Theremax.


There is also an area of aluminum tape near the pitch antenna. It is
interesting, in that this would not present any sort of "ground plane",
even at far higher frequencies.  I assume it is being used as a
capacitor against the antenna, which could be intended to further
increase the control range, by swamping out some of the hand
capacitance. I'm not sure on this point yet.



2005\11\30@162539 by Lindy Mayfield

flavicon
face
I built a Theremax from a kit about 7-8 years ago.  I recall the tuning of the coils to adjust the pitch frequencies to get a tone and match the antenna.  It was a bit tricky at first.

I wish I had known more about what I was working with.  As many people I put it together more like a puzzle than a kit.



{Original Message removed}


'[OT] Theremins'
2005\12\01@170436 by Robert Rolf
picon face

David Van Horn wrote:

{Quote hidden}

Uhh, shouldn't that be 1400200Hz, and 200Hz?
Sum and difference. 200Hz apart means 700khz and 700.2kHz as f1 & f2.

The wide difference in sum and difference products is what makes the
filtering easy. The high carrier frequency makes it more sensitive
to capacitive loading, so the higher your base frequency the wider
the pitch range for a given delta C.

I rather like the idea of an optical thermin.
They'd be just as hard to play, but would be easier for the
digital geek to build.

Ranging could be as simple as a modulated IR source with
a tuned amplifier on the photodetector so that you get a linearish
response to intensity vs hand distance. (1/R^2). Then simple math
to scale to a linear note number times 12th root of 2 note intervals.

You could even cheat and have the PIC 'fix' your bad pitch just
as modern DSPs do for today's not so good singers.


Robert

2005\12\01@173232 by Lindy Mayfield

flavicon
face
Or take it a step further.  If you are using a microcontroller in the equation then why not let it do some of the work for you.

I cannot remember but I think the distances between the antenna and the hand relative to the pitch is ... I don't know what the word is or how to explain what I mean... logarithmic is it?  

For example, from 110Hz to 220Hz, A to A, is one octave or 12 steps on a piano.  From 220Hz to 440Hz is still another A to A octave and 12 steps on a piano or any other instrument.  But the difference between the two has gone from 220-110=110 to 220-440=220.  Logarithmic is that?

But the difference between the steps on a piano are based on distance and therefore equal.  Every key is the same width, of course.  (-:

I'm not sure how the pitch goes on a Theremin but I think it is logarithmic rather than linear.  

My idea is what would a Theremin be like to play if it were linear like a piano with each step being x number of millimeters distance to the antenna?  

A PIC could do the math to make that happen.  I think for me at least I would have to try each one to see which is easier.  But this is a cool topic, for me at least. (-:

What do you think?

-Lindy

{Original Message removed}

2005\12\01@173928 by David Van Horn

picon face
> > For getting the pitch itself, you use a pair of oscillators, like
> > 700kHz-ish.  They sit maybe 200 Hz apart at idle more or less. So
the
> > mix products would be 700200, and 200 hz.
>
> Uhh, shouldn't that be 1400200Hz, and 200Hz?
> Sum and difference. 200Hz apart means 700khz and 700.2kHz as f1 & f2.

Sorry, yes.  Makes no difference in real life, the ckt is only
interested in the low product.

> You could even cheat and have the PIC 'fix' your bad pitch just
> as modern DSPs do for today's not so good singers.

This is a little bit interesting, but you also want the slow glissando
and vibrato, and I'm not sure how you could handle that, without some
sort of "fix me" input to tell it when to let the natural pitch through.



2005\12\01@175619 by Robert Rolf

picon face
Lindy Mayfield wrote:

> Or take it a step further.  If you are using a microcontroller
in the equation then why not let it do some of the work for you.

Uhh, that's exactly what I was suggesting.

Measure hand distance. You want it linear since most
instruments have linear spacing of their keys.

Compute note number.

Do math. N * 1.059463094....(12th root of 2) * base frequency
= note frequency.
Simplest is to compute offline in  spreadsheet and use a lookup table
with some interpolation to get smooth note gliding.

> I cannot remember but I think the distances between the antenna and the hand relative to the pitch is ... I don't know what the word is or how to explain what I mean... logarithmic is it?  

Logbut with a fairly low slope (log vs linear graph paper).

>
> For example, from 110Hz to 220Hz, A to A, is one octave or 12 steps on a piano.  From 220Hz to 440Hz is still another A to A octave and 12 steps on a piano or any other instrument.  But the difference between the two has gone from 220-110=110 to 220-440=220.  Logarithmic is that?
>
> But the difference between the steps on a piano are based on distance and therefore equal.  Every key is the same width, of course.  (-:
>

> I'm not sure how the pitch goes on a Theremin but I think it is logarithmic rather than linear.  

It's actually 1/X because of the inverse square law. Close enough since
the human corrects the pitch.

> My idea is what would a Theremin be like to play if it were linear like a piano with each step being x number of millimeters distance to the antenna?  

Sure. See above comments about how to compute the needed frequency.

> A PIC could do the math to make that happen.  

No hard math needed. Just use a lookup table and interpolate.

> I think for me at least I would have to try each one to see which is easier.  

Easier how? To play or to code?

>But this is a cool topic, for me at least. (-:

> What do you think?

Do it step by step.
Since measuring the hand position is going to be the hardest part
(IMO), start with that.  Use it to directly compute a pitch value for
the PIC timers. Then change the shape of the transfer function (log vs
linear).

Have fun.

But somehow I think it's more 'real' to use RF sensing.

Robert

 > -Lindy
>
> {Original Message removed}

2005\12\01@183812 by David Van Horn

picon face
> I'm not sure how the pitch goes on a Theremin but I think it is
> logarithmic rather than linear.

Pretty much linear, but the highest octave (close to the antenna) tends
to squash.  

> My idea is what would a Theremin be like to play if it were linear
like a
> piano with each step being x number of millimeters distance to the
> antenna?

A lot sweeter.  I suppose you could do that, but you'd have to quantize
the distance, or describe a pretty interesting linearizing formula.




2005\12\01@184101 by Robert Rolf

picon face
David Van Horn wrote:
>>You could even cheat and have the PIC 'fix' your bad pitch just
>>as modern DSPs do for today's not so good singers.
>
>
> This is a little bit interesting, but you also want the slow glissando
> and vibrato, and I'm not sure how you could handle that, without some
> sort of "fix me" input to tell it when to let the natural pitch through.

I am sure there are parameters that allow for adjustment of
such things.

Vibrato is AC pitch modulation around a mean, so it would
be fairly easy to look at the slope of F and decide whether the
singer was moving to the note, or had missed it. Given that
the DSP process introduces a minute delay, you'd never hear
the 'off' pitch.

The Cher song 'Believe' gives a great example of what the
voice processing technology can do now. Harmonizing in real time.

Robert



2005\12\01@192416 by David Van Horn

picon face
> Vibrato is AC pitch modulation around a mean, so it would
> be fairly easy to look at the slope of F and decide whether the
> singer was moving to the note, or had missed it. Given that
> the DSP process introduces a minute delay, you'd never hear
> the 'off' pitch.

Hmm.. I think this might be more interesting than you think.


> The Cher song 'Believe' gives a great example of what the
> voice processing technology can do now. Harmonizing in real time.

The steppy response there would not be something desirable, generally
speaking.


One thing that would be interesting, would be some sort of "Calibration
mode" where you set up a distance for high and low note, and it then set
the scale to that. You'd potentially have to deal with the null point,
and with some fairly high "real" pitch outputs.

The volume antenna's response I suppose could be aided as well, but it's
far less critical. You can't hear a 1mm miss in volume, but you can in
pitch.  Trust me, breathing while playing makes a pitch change.



2005\12\01@194814 by liam .

picon face
I've got an subscription to an electronics mag in Australia, Earlier
in the year there was an article about a MIDI theremin. For those
interested:

www.siliconchip.com.au/cms/A_104173/article.html
http://www.siliconchip.com.au/cms/A_104415/article.html

Also a few years back they ran a more clasic theremin article.

http://www.siliconchip.com.au/cms/A_103277/article.html

2005\12\01@201155 by Dave Lag

picon face
liam . wrote:
> I've got an subscription to an electronics mag in Australia, Earlier
> in the year there was an article about a MIDI theremin. For those
> interested:
>
> www.siliconchip.com.au/cms/A_104173/article.html
> www.siliconchip.com.au/cms/A_104415/article.html
>
> Also a few years back they ran a more clasic theremin article.
>
> www.siliconchip.com.au/cms/A_103277/article.html
>
Let me guess- You guys posting Silicon Chip links have subscriptions and
cookies that log you in so actually see past the first paragraph?
D

2005\12\01@235910 by Jinx

face picon face
> Let me guess- You guys posting Silicon Chip links have
> subscriptions and cookies that log you in so actually see
> past the first paragraph ?

Not me - they have only a few full articles available at their
web site, I have only the print version. Can at least give you
a look at the schematic, for discussion purposes, y'understand

Those with a severe aversion to even the merest copying should
look away now

190kB

http://home.clear.net.nz/pages/joecolquitt/sc_theremin.gif

It's a small part of the overall project, and is useless without
the s/w

2005\12\02@030048 by liam .

picon face
> Let me guess- You guys posting Silicon Chip links have subscriptions and
> cookies that log you in so actually see past the first paragraph?
> D
> --

Sorry.... I've got a print subscription as well. They actually sell
online subscriptions seperate to the print.

If anyone decides to go for a kit rather than build their own, the
kits for those articles are avaliable:

http://www.jaycar.com.au
Origional Design       KC5295
MIDI Version            KC5410

2005\12\02@073349 by olin piclist

face picon face
Lindy Mayfield wrote:
> My idea is what would a Theremin be like to play if it were linear like
> a piano

But a piano is logarithmic, not linear.  Each key produces a frequency that
is 2**(1/12) higher than the one on its left, not some fixed number of Hz
higher.

(Actually original pianos didn't have a single fixed frequency ratio between
keys, but modern "tempered" pianos do).


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2005\12\02@081116 by Lindy Mayfield

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face

You're absolutely correct.  It was J.S. Bach who advocated this new system of tuning, the result of which is that you can play music in all 24 keys without having to retune for some keys.  To prove his point he wrote two volumes of preludes and fugues in each major and minor key called Das Wohltempierte Klavier.  I actually prefer Book II the best.

But I should know better than to be imprecise in this group. (-:

I really meant the physical location of the keys and not the frequencies.

It is interesting though that the physical location of the notes on a violin or guitar are logarithmic as well.  As the notes get higher and the vibrating string is shortned the physical distance between each note gets smaller.


{Original Message removed}

2005\12\02@084520 by David Van Horn

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> Lindy Mayfield wrote:
> > My idea is what would a Theremin be like to play if it were linear
like
> > a piano
>
> But a piano is logarithmic, not linear.  Each key produces a frequency
> that
> is 2**(1/12) higher than the one on its left, not some fixed number of
Hz
> higher.

Other instruments aside, it would be very nice if the distance covered
by all octaves, and the notes within them, were the same.
Expanding that distance, within limits, would be a good thing as well.
But at some point, you reach levels of sensitivity that would make it
unplayable again.




2005\12\02@141458 by Peter

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I really wonder how you would stabilize an original theremin (built with
valves/tubes).

Peter

2005\12\02@142512 by David Van Horn

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>
> I really wonder how you would stabilize an original theremin (built
with
> valves/tubes).

They drift a bit.


2005\12\03@031349 by Bill & Pookie

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As a start to a  pic theremine, it should be posible to use a simple pic as
a variable frequency oscilator (VFO), witj a couple of digital input pins
for slew up/down and on/off,

Bill


----- Original Message -----
From: "David Van Horn" <RemoveMEdvanhornEraseMEspamEraseMEmicrobrix.com>
To: "Microcontroller discussion list - Public." <RemoveMEpiclistspam_OUTspamKILLspammit.edu>
Sent: Friday, December 02, 2005 11:34 AM
Subject: RE: [OT] Theremins


>>
>> I really wonder how you would stabilize an original theremin (built
> with
>> valves/tubes).
>
> They drift a bit.
>
>
> --

2005\12\03@063855 by Lindy Mayfield

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face
There are always the stories about Clara Rockmore backstage before a concert busy with a screwdriver preparing the instrument.  So it seems the original ones were quite high maintenance.

-----Original Message-----
From: RemoveMEpiclist-bouncesTakeThisOuTspamspammit.edu [EraseMEpiclist-bouncesspamspamspamBeGonemit.edu] On Behalf Of David Van Horn
Sent: 2. joulukuuta 2005 21:34
To: Microcontroller discussion list - Public.
Subject: RE: [OT] Theremins

>
> I really wonder how you would stabilize an original theremin (built
with
> valves/tubes).

They drift a bit.


2005\12\03@162454 by Peter

picon face


On Fri, 2 Dec 2005, David Van Horn wrote:

>>
>> I really wonder how you would stabilize an original theremin (built
> with
>> valves/tubes).
>
> They drift a bit.

'A bit' ? <g> I guess you have to turn it on 30 minutes before playing
...

Peter

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