Odp: [sdiy] Level Headed

[Scott Bernardi]

For filters I came up with (well, it's a new idea for me) a variable CV input to
plug the EG into. At the center pot position you get no CV, clockwise you get
increasingly positive amplitudes and counter-clockwise you get negative
amplitudes.  You still have the standard Freq setting for the filter (which
takes care of your offset), and continuously variable positive or negative EG
voltages. The EG's only need a standard zero to positive output.
Only takes one opamp and a pot.  You take the CV input to one end of the pot.
You also run it through an inverter (Av= -1) and tie the output to the other end
of the pot. Then you take the wiper for your variable +/- CV input.
My joystick controller uses this scheme; I don't have the other schematics up
yet.
http://home.attbi.com/~sbernardi/elec/og2/og3_joystick.html

Grant Richter wrote:

> The Synthi and Putney use +/- voltage for the envelope. This produces a
> somewhat odd effect when you attenuate them as you now have to adjust the
> filter offset as you adjust the envelope sweep depth to set the filter
> range.
>
> Not a problem, but a bit twiddly. An envelope could have a 0 to + or - range
> to help in setting the filter sweep.
>
> >> I use +/- control voltages as well, so that make two freaks.  And
> >> the signals I basically treat the same way as you do.  Why put limits
> >> that restrict your fredom.
> >>

--
Scott Bernardi
sbernardi at attbi.com