[sdiy] New TOG board: $0.02 needed / Walsh

[Tim Ressel]

Harry, I don't understand. How would that work? What would that be useful for?

--Tim (thick as a brick) Ressel


--- On Wed, 1/7/09, harrybissell at wowway.com <harrybissell at wowway.com> wrote:

> From: harrybissell at wowway.com <harrybissell at wowway.com>
> Subject: Re: [sdiy] New TOG board: $0.02 needed / Walsh
> To: madhun2001 at yahoo.com, synth-diy at dropmix.xs4all.nl
> Date: Wednesday, January 7, 2009, 9:56 AM
> You could use simple analog switches as multipliers for a
> Walsh
> coefficient system... the square waves (or Walsh functions)
> drive the
> control input, the analog outputs are summed, and control
> voltages fed into
> the analog input. No digital pot needed, CVs can be input
> directly
> 
> H^) harry
> 
> 
> 
> 
> On Wed, 7 Jan 2009 09:25:06 -0800 (PST), Tim Ressel wrote
> > FYI:
> > 
> > Cheap digital pot: MCP4231-103E/P-ND (DigiKey)
> > Dual 10K (other values available) $0.68 in 100 pcs
> > 
> > That's $0.34 per pot. Not bad. 12 notes * 8 Walsh
> coefs per = 96 
> > pots = $32.64.
> > 
> > Another cool thing: since all notes will have the same
> timbre (?)
> >  the digital pots can be tied together and all clocked
> at once.
> > 
> > Of course that is going to be one nightmare board to
> lay out....
> > 
> > --TimR
> > 
> > --- On Tue, 1/6/09, Nicholas Gregorich
> <nicksdsu at mac.com> wrote:
> > 
> > > From: Nicholas Gregorich <nicksdsu at mac.com>
> > > Subject: Re: [sdiy] New TOG board: $0.02 needed
> > > To: music.maker at gte.net
> > > Cc: synth-diy at dropmix.xs4all.nl
> > > Date: Tuesday, January 6, 2009, 8:08 PM
> > > Scott Gravenhorst wrote:
> > > > Scott Nordlund <gsn10 at hotmail.com>
> wrote:
> > > >> I've always wanted to retrofit a
> TOS-based
> > > synth with something that output Walsh functions
> instead of
> > > simple 2'/4'/8'/16' squares. Of
> course this
> > > would require all the octave dividers to be
> replaced (with
> > > CPLDs?) 
> > > > 
> > > > IMO, an FPGA would be more appropriate, lots
> more
> > > logic to play with.  Then you can go completely
> > > > nuts with the design.  Also, a CPLD has no
> dedicated
> > > multipliers, AFAIK, a Walsh synth would need
> > > > multipliers so that each logic output can be
> amplitude
> > > controlled rather than simply on/off.  An
> > > > FPGA has this capability.
> > > > 
> > > 
> > > If you control amplitude in the FPGA then you
> need a DAC
> > > (rather than just an output pin) and a way to
> control the
> > > amplitudes (MIDI or ADC).
> > > 
> > > I think part of the beauty of a Walsh generator
> is that you
> > > can actually put it in a small CPLD and build a
> mixer,
> > > that's it. No development kits  needed.
> > > 
> > > Nicholas
> > > _______________________________________________
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> > >
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> 
> 
> Harry Bissell & Nora Abdullah 4eva