ARP 2600 - Page 94

89
6
Pulse-width
modulation.
Since
only the trailing
edge
of the
pulse
is
affected,
AF
modulation of
the
pulse will cause the trailing
edge to
become
a
series
of shorter
pulses at
a
frequency
equal to the modulating
frequency.
A
number
of timb.ral effects
becomes
possible
in
this fashion
that
would
be difficult to
achieve
by
any
other
means. Note that
if
the
modulating
signal is a
positive-going
waveform only,
such
as the
2600's
square, pulse,
and
sawtooth
waves, then
the
initial setting
of
the pulse
width
control
should be
at
minimum;
but
if the modulating
signal is
balanced on either side of OV
then the Initial
pdse-width
setting should
be at 50%.
Width
Modulation)