building my first synth

[DocteurU at info.polymtl.ca]

Rich Holmes writes:
> haines at quick.net (Matt Haines) writes:
> ...
> >The MIDI bit's the hardest part. You're better off buying a midi/cv
> >converter, and then controlling the cv inputs of the synth with it, if that
> >doesn't violate the purpose of the exercise.
> 
> ... and if that doesn't violate your bank account!  I mean, come on --
> does it *really* make any sense to shell out a couple hundred bucks or
> more on a MIDI->CV box to control something on the order of a PAiA
> Gnome? 
> 
> Or am I woefully ignorant on the subject of how cheap a MIDI->CV box
> can be had for?  The lowest price I know of is for the Fatman (with a
> synth thrown in for free), at $150 if you don't mind doing the
> soldering and making your own rack panel and if you're driving linear,
> not exponential, modules.
> 
> Seems like, if PAiA can put that into a $150 synth kit, it ought to be
> possible for a DIYer to build a simple MIDI->CV module for under 40
> bucks.  In fact, why not build the digital section of the Fatman?  
> 
> If one did so, would it be merely a software (firmware) hack to make
> it drive exponential modules?
> 
> -- 
> - Rich Holmes
> 
>     "Not every tradition, however entrenched, is attractive.  Some
> 	 should be closed down immediately." -- Miss Manners
> 

	I am doing this synthesiser as a university project, so I could
use good equipment (oscilloscope and all) without buying them....
The problem is I'm doing this as a computer engeneering project...
(I think I am quite lucky they accepted it) So leaving the MIDI part
is leaving the computer related part....

	And I don't think it will cost much money either. If I ignore
most of the MIDI messages except note on note off messages I would only
need a bad UART (7$) a couple of 74ls74 for memory (10$ max) some XOR
NOR AND etc (which I already have) and a digital to analog converter
for giving the CV output (I think a MC1408 might do the trick) 5$ or less...
Connections, protections and a couple of switches to select the midi channel...
And a couple of 74ls138 (or is it 136?). Actually less than 50$.. 

	The trouble I might have is having the DAC convert the MIDI note
into CV... Now I don't know what are exactely the CV gate specifications...
(is it 1 volt per octave?) .

	And of course, I live in Montreal Canada... finding a MIDI - CV 
converter over here might be difficult.  

Ben

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* Signe Benoit Piette ou si on veut, Le Docteur U                           *
*  DocteurU at info.polymtl.ca                                                 *   *=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*