WASP filter clone finished

[Martin Czech]

I've now finished my version of the WASP filter clone (thanks to Juergen
Haible for support and schematics).

I've now added the following to the original schematics:
-the ota divider is 51k, not 100k , like Juergen proposed
-the hex inverter has it's own, variable supply (1.25 to 7 V via LM317T)
-the  otas run with -+15V
-thus I'm able to use the normal pnp expo converter (Formant) referenced
 to GND, I use a CA3096 package. Hfe is only ~90, but this should be ok.
-the distortion stage (one inverter) now has another inverter that can
 have adjustable dc input offset, this works like a pulse shaper when
 strong overdriven, with not so much drive it adds some even harmonics.
-the distortion unit can be switched pre- or post filter, the later
 uses only the bandpass output (less intermodulation). The distortion
 unit has a seperate output.

I found it necessary to have variable supply for the inverters, this
can change the sound very much. Freqeuncy stays where it is however.
Pre or post distortion gives also different results. The dc offset into
the distortion unit gives another range of sounds.

Man, I could sit and play for hours with this little, cheap module.

Next, I'll think about module frontplate and cases.
And when I've finally got an update of Corel Draw, a schematic will follow.

m.c.