Date: Mon, 3 Apr 1995 19:25:42 +1000 (EST)
From: Damien Miller <s9506190@minyos.xx.rmit.EDU.AU>
Cc: analogue@hyperreal.com
Subject: Re: CV Problems & Questions

On Sun, 2 Apr 1995, Derek Christopher Jeter wrote:

> On Sat, 1 Apr 1995, Bulbous Concerns wrote:
> 
> > Another thing that sucks about Moogs is that they always put the portamento
> > circuit in the keyboard, and not on the CV in.  DAMN!
> 
>  My Roland SH09 is like that too. Very annoying. Anyone know how to get 
> around that? Is it difficult to build a portamento circuit?

here is a cheapy slew-rate limiter circuit:

                    CA3080
 
 Vin o---o-----o------|\
         |     |      |+\                 TL081
         |     |      |  \
        / \   \ /     |   |----o-----------|\
 1N4148  |     |      |  /     |           |+\
         |     |      |-/|     -           |  \
         o-----o------|/ |     - 100n      |   |---o-----o Vout
                   |     |     |           |  /    |
                   |     |    GND          |-/     |
                   |     |              |--|/      |
                   o---------/\/\/\-----o----------o
                         |    47k
                         |                          o  +Vcc
                         o---/\/\/\--------o        |                 
                             150k          |        \            /\ Faster
                                           |        /
                                           o------->\  10k log
                                                    /
                                                    \            \/ Slower
                                                    | 
                                                    o -Vcc

I haven't actually buit this yet, so tell us how you go. The circuit 
looks nice because it can be voltage controlled.

>  Finally, if I use portamento via MIDI (I forget the controller number), 
> will the Roland MPU-101 track it? From my experience, it doesn't seem to
> want to...

It hasn't worked for me.

Damien

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| Damien Miller a.k.a s9506190@minyos.xx.rmit.edu.au a.k.a Silicon Dreams |
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