[sdiy] Serge NTO-type waveshaper

[mark verbos]

Well, It's an oldie, but goodie I think.

Has anyone come up with a take on the Serge NTO-type waveshaper? That 
is, an oscillator with an output that can sweep continuously from saw to 
sine to pulse to square form voltage. There is of course the Kobol 
waveshaper, but that one uses a triangle and not a sine. Also, I think 
with the NTO type you can get both of the Buchla 258 sounds since the 
sine is in between the saw and square (yeah I know the pulse is in 
between the sine and square, but close enough).

one thought i have is to use the concept from the Buchla 208. That's a 
sine oscillator that fades in the saw  and the square (both mixed with a 
negative version of the sine) from a frossfading circuit with a dead 
zone in the middle. Then make that same control do the PWM. Can you make 
 the transistor pair crossfader (for the vactrols) have a dead zone? Do 
you just increase the resistor between the emitters?

3080s could work too.

seems to be a cool circuit.

any ideas?

anyone have the real schematic? I heard it uses a 3900. I just want to 
see it. I won't tell anyone ;)

mark