MOTM

Larry,

Your module sounds very neat.  I can see many uses for it, not just for keyboard
CV->VCO.  Perhaps you should have a discussion with Paul about making it a MOTM
utility module and getting some royalties ;^)  Seriously, I'm not likely to build up
my own module like this (soldering is not a big deal but the mechanical stuff always
gives me problems) but I would be interested in buying a professionally constructed
version with the appropriate panel, etc.

Eric

P.S.  I would call it a voltage shifter instead of a pitch shifter...


> 
> This module is a manually controlled pitch shifter.  I started to make this
> just an octave switch, as I wanted a way to shift octaves and maybe 5ths
> between my MOTM oscillators without having to retune them.  I just like
> having octave switches on an oscillator.  BUT, the MOTM-300's pot control
> offers more range and I did not want to even THINK about modifying the
> greatest oscillator module on the planet.  So, my original plan was to make
> a module that put out a selection of fixed voltages that could be connected
> to one of the FM inputs of the MOTM-300 to provide this feature (real simple
> stuff).  There was some discussion on the list.  However, Ken Tkacs twisted
> my arm around my back (a neat trick via e-mail) and told me my plan should
> be modified so that the 1 volt/oct voltage keyboard CV connects to my
> module, and then my module connects to the MOTM-300 or any 1 volt-oct VCO.
> After first dismissing this as too difficult for a guy with a business
> degree, I finally admitted Ken was right (like he almost always is BTW), and
> adopted his concept for my project.
> 
> The result is a 1U utility module with three rotary switches for interval
> selection and six 1/4 jacks (3 CV IN, 3 CV OUT).  Each interval switch can
> be used separately, or all outputs controlled by the same keyboard CV
> (normalled a to b, b, to c).  This simple circuit adds the selected voltage
> interval to the incoming keyboard CV and that is the output.  This first
> version has 5 interval shifts up and 5 down.  There are three channels of
> shift.  The interval shift amount is completely "user selectable" by the
> fixed resistor selection in a corner or the circuit board (when building).
> I was going to use only octaves and 5ths.  But along the way with my
> experimenting, I found many other useful and interesting harmonics (Thanks
> Ken)
> 
> So, you hook your keyboard CV to the input of the module.  You hook this
> module's CV outputs (3) to the 1-volt-oct inputs of your oscillators and
> tune all the oscillators in unison (at the high end of the CV range BTW).
> Then you can use the rotary switches to shift the intervals between
> oscillators.  Of course, one oscillator (your fundamental frequency) does
> not need to pass through this module.  I have the module constructed and
> tuned and it works quite well.
> 
> Version # 2 of this module, will feature only 2 channels of shifting (yes,
> we can get by with 3 oscillators per voice).  However, it will have MUCH
> more shifting capability.  It will have 4 rotary switches and 4 jacks (2 CV
> IN and 2 CV OUT).  The difference is that ANY semitone interval is
> selectable.  Since each shift channel has 2 switches, one will select
> octaves up and one octaves down.  The other will select intervals in
> semitones +1 through +11.  So, no user interval choice will be required when
> building.  Version # 2 is layed out on paper proto board but will not be
> tested and functional for about a month.  I am taking a 2 week vacation to
> the Washington, Idaho, Montana and Calgary, Canada.  So, I will start
> constructing it when I get back.
> 
> Obviously, these are simple circuits consisting of resistor voltage dividers
> for interval voltages and op amps for DC adding.  The trick has been getting
> the accuracy in the 1 volt/oct CV.  If anyone has any additional interest in
> either of these two utility modules, please e-mail me off list.  I don't
> want to turn the MOTM list into DIY discussion for the many that don't
> build.  However, since this is created in the MOTM format for use with MOTM,
> I wanted to share it with the list.
> 
> Thanks to Ken Tkacs for his inspiration and to Paul for answering the one
> hundered stupid Stooge-like questions.
> 
> Larry Hendry
> 
> Disclaimer:  I am not a BS/MSEE.  I am not a design engineer.  This is DIY
> learning stuff.  My only claims are that:
> 1 - I am having fun
> 2 - My circuit works very well
> 3 - I am buying more MOTM proto boards than anyone else.
> 
> 
> 
> 


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