Through-‐Zero VCO Manual 0.1
9
Calibration
There are two trimmers that need adjustment for correct operation of
this module.
Saw Offset
The Saw wave is generated from the double-frequency saw by
summing it with the Square wave. This trimmer adjusts the amount
of square wave added to eliminate a discontinuity as the waveform
crosses zero-volts. It is best adjusted while monitoring the Saw
output on an oscilloscope, however it can be adjusted roughly ‘by ear’
if necessary. This is trimmed during manufacture and it is unlikely to
need further adjustment.
1-‐volt/octave Scaling
The module is supplied pre-trimmed for 1-volt/octave scaling on the
input connected to the Doepfer 16-pin header, but users may wish to
adjust this to match their specific CV source.
Before starting, if the CV signal on the header is used then ensure
that the supplied jumper is fitted. If the 1-volt/octave jack on the
front panel is the primary CV input then the jumper may be removed.
The module must be powered and left for the temperature to stabilize
to make calibration easier.
The calibration procedure outlined assumes that a keyboard is used
as the CV source, but the method can easily be modified for other
controllers.
