I have replaced the LM324 quad op-amp specified for IC4 with a TL074. This has the
effect of sharpening up the transients on the pulse output, producing more rectangular
waveforms. Basically the slew rate of the TL074 is 26x faster than the 0.5V/uS of
the LM324 which tended to produce triangular waveforms at moderate frequencies.
Here's some 'scope shots (not too well focused, I'm afraid) of a 410Hz triangle wave
fed to 'TRI IN' and the resulting folded out and pulse out.
Top trace 'FOLD OUT'
Bottom trace 'TRI IN'
Top trace is the same 'FOLD OUT'
Bottom trace is 'PULSE OUT' with LM324 in position IC4
Notice the slew limiting in the bottom trace.
Here's the same thing again, but this time the LM324 has been replaced by a TL074.
The pulse output is much sharper.
As IC2d is going spare in the current circuit, it should be possible to utilise both
the TL074 and LM324 for the pulse out, and just switch between them with a toggle,
which would then feed the 'PULSE OUT' jack. This would give a 'hard' or 'soft' pulse
out. I haven't implemented this yet.
When manipulating the folds, offset and PWM with external CVs, it's possible to get
very animated timbres from this module.
Sound clips to follow.
Here's the Wavemultiplier installed (top right)
My version of the Scheaffer front panel data is here