Vocoder design

[Scott Bernardi]

U3:B is an input buffer, U1:C and U1:D make up the bandpass filter, U2:A and U2B
make up a negative peak detector with two poles of filtering by R21/C9 and
R20/C10.
U2:C and Q1 make up a voltage-to-current source that is feeding the IC2 OTA.

danial stocks wrote:

> >
> >If it does require more than 12db/octave filters, I think the circuit gets
> >too complex. Also, the phase changes would get
> >pretty crazy, I think.
> >One thing I was going to try is alternate the polarity of the inputs on
> >each channel so the responses between the channels
> >would add, and therefore flatten out the overall response.
> >
> >hi Scott..
> nice schem.. I'm impressed that it's all std res &cap vals.. I think you
> could get away with a 1/2 wave rect for most of the chans.. ditch an op amp,
> or use for an extra filt stage.. prolly from 400 hz ^ you could reasonably
> do this.. I'd use an i/p buffer on the inputs 1 buffer for everything.. even
> if the imp is high enuff not to need one, i/p, o/p buffers also protect the
> inner organs from outside world of power surges etc... ie you only maybe
> blow up one op amp instead of a stack of them.. so place it convenient for
> easy changeover..
> 1 bit I dont get.. what's the go with u2c/trans? current source? havent seen
> this, too tired to be figuring it out..
> Cheers,
> Dan
> _________________________________________________________________________
> Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.
>
> Share information about yourself, create your own public profile at
> http://profiles.msn.com.

--
Scott Bernardi
sbernardi at home.net