[sdiy] Oscilloscope (not damaged by UPS) and theremin

[harry bissell]

Hi Christian

--- Christian Oncken <Christian at dslab.com> wrote:

> 2.  I've been trying to build the theremin
> controller from the glascow
> digital theremin schematic (updated version) found
> here:
> 
>
http://www.thereminworld.com/files/projects/glasgow/revised.gif
> 
> I thought this would be a great controller for my
> modular, as I'm mostly
> doing effects on it and such.  I looked at the
> schematic, and I cant
> understand why 2 different 4093 chips are used when
> the 4093 is a quad
> chip...

The dreaded "soft sync" is the reason. With both
oscillators in one package (VERY close together and
sharing the power pins...) they will lock. In a
theremin you need to "zero beat" the oscillators...if
they lock you won't be able to play it very well.

I suppose you can try to make it work... but maybe yes
maybe no....

H^) harry


 Another version of this replaces the 4070
> with a 4077 so the last
> schmidt trigger isnt necessary.  Is there any reason
> why one couldnt use 1
> 4093, utilizing all 4 of its schmidt triggers, to
> build one of these things?
> I tried it and I cant get it to work...  Any ideas? 
> Tips?  A 3 chip
> theremin would be super cool...
> 
> thanks in advance...
> 
> Christian.
> 
> 
> 


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