ARP 2600 - Keyboard Controller Controls: Tone Interval

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It
fed to the
three VCO's and the VCF. In
addition,
the
KBD CV
becomes
available
at the
output
jack
located in the
extreme
lower
left corner
of
the
2600 main unit,
and the
GATE
and TRIGGER outputs
are
available
at
two
jacks
located
in the Envelope Generator section.
When
any key is
depressed, the GATE
voltage
immediately rises
to +10V and remains at that value
until the key is released again, upon
which the gate voltage returns immediately to
zero. If more
than
one
key is depressed simultaneously, the
gate voltage does not fall
to
zero
until
they have
all
been
released.
The function of
the
gate voltage, in
other words,
is
only
to
indicate that
at
least one
key
is
depressed.
At the
instant a
key is
depressed,
the
TRIGGER voltage rises
to
approximately
+15V
and instantly returns to
zero.
This trigger
output appears
EVERY
time a key is
depressed,
regardless of how
many
keys
are already being held
down. The
function
of the trigger, in other
words, is
to
indicate the exact
instant
at
which any key
is
depressed.
Releasing
a
depressed
key
has
no
effect
on
the trigger output.
When any
key is
depressed, the
KEY-
BOARD CONTROL VOLTAGE
immediately
assumes
some value from OV to somewhat less
than +8V
depending on which
key
is
depressed
and
on the
settings of the INTERVAL and TUN-
ING controls
at the front of
the
keyboard. The
output
will remain
at
this
voltage
until
another
key is
depressed, even
after the first key is
re-
leased:
a
"memory"
circuit
in the
keyboard
holdsthe voltage until it
is
changed by
depressing a
different key.
If
more than
one
key is depressed
simultaneously, the
control
voltage
output
will
be
governed
by
the lowest, or
leftmost,
key, and will not
be
affected
by
depressing any
key
to
the right of
that key.
4.341
At
the front of
the
3604
Keyboard
Controller are several con-
trols
that affect the behaviour of
the keyboard
control voltage.
Each
is
activated
by
a
switch and
governed
by a
knob.
The TONE
INTERVAL
control
is
essentially a
precision
atten-
uator
for
the
control
voltage.
When the slide switch
for
this
control is
in
its RIGHT-HAND position,
the output voltage
passes through an
attenuator that is factory-calibrated
to give exactly one volt
output
per
keyboard octave, or
four
volts from one
end
of
the
keyboard to
the