DC Transfer function problem...

[john..]

Hello all,
	over the last couple of days I've been trying to build a
compressor/waveshaper using a VCA block (based on an LM13700) and some
control circuitry. I'm having difficulty in generating an appropriate DC
transfer function for the control circuit: what I'm after is a transfer
characteristic something like this:

Vout
   |
   |
   |--------------\
   |               \
   |                \
   -------------------------------
        Vin

where both the `knee' point (threshold) and the slope (compression ratio)
can be changed independently. Note that this *isn't* a frequency domain
graph :)

(I've already managed to build an envelope follower to feed into this
circuit, as well as the VCA.)

I've spent quite a bit of time reading Horowitz & Hill, as well as
numerous R.A.Penfold books, and Hal Chamberlins book....!


Cheers (I'm probably being *really* stupid!)

john..

---------------------[ j   o   h   n       t   u   f   f   e   n ]--
---------------------[email]---------------------[jat5 at york.ac.uk]--
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