Doepfer

> Hi!  My first post.
>
> Is it possible to modify the A-143-1 for linear response
> envelopes?  I have
> purchased one as a modulation source in my video synthesis system, shown
> here:
> http://www.lzxindustries.net/introduction
>
> For video, the exponential response envelopes are not as useful as I would
> like, but otherwise the module is fantastic for my purposes!
>
> Please let me know if there are any tips on doing this
> modification, or if a
> portion of the circuit schematic is available so I can attempt to
> figure it
> out.
>
> Thank you,
> Lars Larsen
> LZX Industries

Sorry that's not possible with justifiable efforts. Standard envelope
generators (like the A-140 or A-143-1/2) are based on a simple
charge/discharge circuit where a capacitor is charged/discharged via a
variable resistor (rotary potentiometer). This generates the well-known
exponential response. To obtain a linear response a voltage controlled
current sink/source would be necessary instead of the resistor. Such a
circuit is much more complex than a simple potentiometer. It is used e.g. in
the VCADSR A-141 which is much more expensive than the
non-voltage-controlled version A-140.

Best wishes
Dieter Doepfer