[sdiy] filter cutoff and pitch manipulator idea involving joy sticks

[Tim Parkhurst]

Yeah, I meant 3914... the 3915 has log response and won't work quite right
in this application. 

Oh and yeah, just hook the 3914 outs to the pot. You've got +V coming out of
the chip and you just divide it down with the pot. Really don't need the
extra switches and all that baloney. That's what I meant to say, really I
did. ;)


Tim (Dave got it right) Servo

"Imagination is more important than knowledge." - Albert Einstein

****************************************************************


> -----Original Message-----
> From: Dave Magnuson [mailto:resfreq at hoohahrecords.com]
> Sent: Wednesday, October 13, 2004 2:49 PM
> To: Milo Barrowclough; synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] filter cutoff and pitch manipulator idea involving
joysticks
> 
> 
> >
> >Yes, you want a quantizer. The Blacet Mini Wave is one solution
> >(<http://www.blacet.com/MW.html>www.blacet.com/MW.html). The PSIM-1 is
> >another (<http://www.synthmodules.com>www.synthmodules.com). But this is
> >Synth DIY, so...
> >
> >Two solutions come quickly to mind:
> >
> >1) The brute force method is to use a number of comparators and pots. The
> >comparators can be adjusted to the range of travel that you want, which
is
> >kind of nice. You may or may not need some logic so that you only have 1
> >active output at a time. If you will set these once and leave them alone,
> >then you don't -- but the output CV will be a summation of all the active
> >outputs. Easier to picture in my head than to explain.
> 
> How about an LM3914 bar graph driver in dot mode?    That would take care
> of the comparators... each segment could connect to the pots like you
> mentioned above.
> 
> The 3914 has more outputs than you'd need (if you want only 5 pitches),
but
> you could just make sure the joystick is only putting out enough voltage
to
> trigger the 3914 up to the first 5 segments (So V+ fed to the joystick
> would need to be about half of the reference voltage fed to the 3914; that
> way the max voltage from the joystick will only activate up to the 5th LED
> output , rather than the last LED output)
> 
> One 3914, some pots, a few passive components and maybe a TL071 summing
> amp... pretty simple.   The page at national semi is here:
> www.national.com/pf/LM/LM3914.html
> 
> The LEDs shown on the datasheet would be replaced by your voltage divider
> pots and a summing amp... and you need to make sure you treat the "mode"
> pin correctly to get dot mode, instead of bar mode
> 
> Dave Magnuson
> 
> PS... I've never abused the 3914 in this method... so I'm not 100% certain
> that the outputs will be consistent every time.  Anyone try something like
> this before?
> 
> 
> 
> Resonant Frequency:
> resfreq at hoohahrecords.com
> http://www.hoohahrecords.com/resfreq/index.html
> 
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