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TI-99/4A Theremin


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#1 Stuart OFFLINE  

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Posted Fri Dec 28, 2018 7:16 PM

A little project I've been working on - to produce a simple TI-99/4A theremin. Implemented using a pair of analogue distance sensors (one for frequency, one for volume) connected to a multi-channel I2C analogue-to-digital converter, which is interfaced by bit-banging the joystick port. A bit tricky to play any sort of recognisable tune at the moment as (1) the sensor outputs could do with a bit of smoothing and (2) I haven't got a musical bone in my body.

 

https://youtu.be/95P-vL_4Hbc



#2 Ksarul OFFLINE  

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Posted Fri Dec 28, 2018 9:26 PM

Oooohhh, the Theremin is one of my favorite instruments. . .



#3 Vorticon OFFLINE  

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Posted Fri Dec 28, 2018 9:45 PM

Cool project :)



#4 Schmitzi OFFLINE  

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Posted Sat Dec 29, 2018 4:25 AM

Great :lust:



#5 ti99iuc OFFLINE  

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Posted Sat Dec 29, 2018 9:52 AM

very nice :) 



#6 Lee Stewart OFFLINE  

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Posted Sat Dec 29, 2018 10:10 AM

A little project I've been working on - to produce a simple TI-99/4A theremin. Implemented using a pair of analogue distance sensors (one for frequency, one for volume) connected to a multi-channel I2C analogue-to-digital converter, which is interfaced by bit-banging the joystick port. A bit tricky to play any sort of recognisable tune at the moment as (1) the sensor outputs could do with a bit of smoothing and (2) I haven't got a musical bone in my body.

 

https://youtu.be/95P-vL_4Hbc

 

Cool project, indeed!

 

I see, er hear, what you mean about needing smoothing the outputs.  There are plenty of musicians on this forum who would likely be interested.  |:)

 

...lee



#7 Opry99er OFFLINE  

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Posted Sat Dec 29, 2018 10:26 AM

I'd be happy to help in any way I can.... but the theremine is not really a structured musical instrument... it is a set of analogue inputs which cover a wide spectrum of tones and frequencies. It can create chaos as well as it can create music.

#8 Ksarul OFFLINE  

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Posted Sat Dec 29, 2018 3:58 PM

Chaos is good. . .



#9 senior_falcon OFFLINE  

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Posted Sat Dec 29, 2018 8:14 PM

Here is my Moog Etherwave standard theremin. I also have a vintage Moog Melodia theremin. The theremin can do a lot more than make spooky sounds for halloween. The best players can really make this instrument literally sing. Look up videos of Clara Rockmore, Peter Pringle, Carolina Eyck and others.

 

gallery_34177_1100_414940.jpg



#10 TheBF OFFLINE  

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Posted Sun Dec 30, 2018 8:02 AM

 

Cool project, indeed!

 

I see, er hear, what you mean about needing smoothing the outputs.  There are plenty of musicians on this forum who would likely be interested.  | :)

 

...lee

 

This is an interesting instrument design question.  The original Theremin was analogue of course an so had essentially infinite frequency resolution within its possible range.

This made it like a trombone or violin in that the player had to set the frequency by ear.

 

The digital Theremin can tame this with preset steps, like a guitar or piano does. I think Stuart has done this in his implementation which is easier to play.

Doing preset pitches of course loses some of the magic of the instrument to create the eerie sounds that we traditionally hear from a Theremin.



#11 Stuart OFFLINE  

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Posted Sun Dec 30, 2018 10:37 AM

 

This is an interesting instrument design question.  The original Theremin was analogue of course an so had essentially infinite frequency resolution within its possible range.

This made it like a trombone or violin in that the player had to set the frequency by ear.

 

The digital Theremin can tame this with preset steps, like a guitar or piano does. I think Stuart has done this in his implementation which is easier to play.

Doing preset pitches of course loses some of the magic of the instrument to create the eerie sounds that we traditionally hear from a Theremin.

 

That's right - at the moment the sensor output is mapped to just 15 notes - I was going to try to play a Christmas carol, but difficult to repeatedly position a hand to play a certain note.






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