[sdiy] Serge CV input circuit?

[Magnus Danielson]

From: Scott Gravenhorst <music.maker at gte.net>
Subject: Re: [sdiy] Serge CV input circuit?
Date: Mon, 03 Sep 2001 08:44:55

Hi Scott,

Sorry for the long quote.... but I could not quickly find out how to
best shorten it.

> What page is this schematic on?  I drew this out and 
> it doesn't seem to me that it will do what is required
> as I understand it.  (which is that at one extreme of
> the pot rotation, the signal is full amplitude and
> positive sign.  In the middle, output is zero.  At the
> opposite extreme, amplitude is again maximum, but
> the sign is negative.)
> 
> This is a rough estimate of what I believe will work:
> 
> 
>                           A
>                +------\/\/\/\/\---+
>                |                  |
>                |   |\             |
>                |   | \            |
>                |   |  \           |
>                +---| - \          |
>                |   |    \         |
>                |   |     \        |
>                /   |      \       |
>                \   |       \      |
>                /   |        \     |
>  *---/\/\/\--->\   |         >----+--->
> input          /   |        /     output
>                \   |       /
>                /   |      /
>                |   |     /
>                |   |    /
>                +---| + /
>                |   |  /
>                |   | /
>                |   |/
>                |   
>                |
>                \
>                /
>                \
>                / B
>                \
>                /
>                |
>                |
>               GND
> 
> This should work if all resistors are the same value,
> eg: 50K.  Resistors A and B could be increased to
> increase the DC gain.

If you view this as a precission diffrential input amp I think the end
result will be what you want to acheive, more or less at least.

Cheers,
Magnus