[sdiy] NIC-waveshaper progress

[Theo]

The wave-shaper section in my QUAD filterbank and my Tidal  Wavefolder
guitar pedal use the same circuit.
However with normal diodes anti-parallel to ground instead of zener.

Theo


From: Grant Richter <grichter at asapnet.net>
To: Ian Fritz <ijfritz at earthlink.net>; <synth-diy at dropmix.xs4all.nl>



> Hello Ian,
>
> I am using a circuit you may find interesting.
>
> Take the standard invert/non-invert circuit using 100K resistors and a
JFET
> switch from op-amp plus to ground.
>
> Replace the JFET switch with a zener diode to ground. For positive
voltages
> the circuit will act as a voltage follower up to the zener voltage, then
as
> an inverter above the zener "fold" point. So with a 5 volt zener, a 0 to
10
> volt sawtooth will be converted to a 0 to 5 volt triangle. Lower resistor
> values give a sharper knee. A TL431 can make an adjustable fold point.
>
> Low impedance output, single op-amp section.
>
> I'm using the circuit as part of the "Joystick Axis Generator" to convert
> the X and Y voltages to a "dome" function for a 2D equal power correction
> curve.
>
>