Patch
Panel Description operational amplifiers
. . . Eight high gain, single ended, inverting amplifiers are brought out
to the panel for traditional analog computer patch cord programming. (The non-inverting
base connected to ground creates the single ended configuration. The inverting
base then typically becomes the summing junction.) GP-10S amplifiers feature high
gain, high input/low output impedance, low temperature drift, sufficient output
current to drive general purpose program loads, 6 db/octave roll-off characteristics
to assure stable, repeatable operation under widely varying resistive/capacitive
input and feedback impedances. Color coding: red, amplifier
outputs; gray, summing junctions. summer/integrators
. . . Amplifiers 1 thru 4 each have an internal FET electronic switch network
that creates SJ and SJ' summing junctions, switched summing junction paths required
for an integrator's two primary modes: initial condition and operate. (Logic patched
to the SW jacks control the switches.) An amplifier is programed as a summer/integrator
by patching a capacitor as the feedback. The output voltage equals the inverted
integral of the sum of the input currents (plus/minus the initial condition) where
the integration rate is the reciprocal of the R*C time constant. (Analog computer
programming assumes a "1" resistor and "B" capacitor to produce
a nominal one second. Actual time constants are determined by the actual resistor
and capacitor values.) Switch logic: Ground or a positive voltage
applied to the SW jack places the switch into the initial condition (SJ' conducting,
SJ shut off) state. A negative 3.5 volts or less places the switch into
the operate (SJ conducting, SJ' shut off) state. A negative 2 thru 3 volts
places the switch into a "hold mode," HD, state where the summing resistor
network is electronically disconnected and the capacitor holds its charge until
placed back into either IC or OP. Color coding: red, amplifier
outputs; green, resistor and IC inputs; gray, summing junctions; white, control
logic. summer amplifiers . . . All patch
panel amplifiers (1 thru 8) may be programed as summers by patching a resistor
feedback. (Regarding the above discussed amplifiers 1 thru 4, absence of SW control
patching latches the SW logic into the SJ conducting, SJ' shut off, state, a configuration
identical to the other amplifiers. Amplifiers 1 thru 4 offer the feature of using
the IC network by patching SJ to SJ' so that the initial condition resistor becomes
a "1" resistor feedback and the IC input an addition "1" resistor
input.) Resistors may also be externally connected. Comdyna offers
special module-plugs to add inputs or special non-standard resistor values. Color
coding: red, amplifier outputs; green, resistor and IC inputs; gray, summing
junctions. coefficient potentiometers . . .
Coefficient potentiometers are configured as attenuators (bottom ends grounded)
to be used primarily for entering parameters (constants) into a program. As an
attenuator, an input (top jacks) is multiplied by its "setting," (an
adjustment between 0 and 1.0,) where the wiper is the output. A coefficient is
set by depressing the adjacent button which replaces the top patched input with
+10v so that the wiper voltage indicates the top to total resistance ratio which
is the setting. Color coding: yellow, inputs and wipers. initial
condition potentiometers . . . Initial condition potentiometers, like coefficient
potentiometers, are configured as attenuators but are used only to enter summer/integrators
1 thru 4 initial conditions. The adjacent toggle switch enables initial conditions
to be both negative and positive or, in the center-off position, zero. Color
coding: yellow, inputs and wipers. multiplier/dividers
. . . Four multiplier networks may be programed for multiplication and/or
division of two analog variables. Multiplication (X * Y) occurs when the network
is patched to an amplifier summing junction and the feedback is a resistor. Division
(U / X) occurs when the network is patched to the summing junction, the Y input
is patched as the feedback, the denominator is patched to the X input and the
numerator U to an input resistor. Color coding: brown, inputs;
gray, network summing junction. positive/negative
10v reference . . . A precision, positive and negative 10 volts reference
provides a "unity" needed for entering voltage constants. Color
coding: red, plus 10 volts; yellow, minus 10 volts. overload
indicator . . . A light alarm glows when any of the eight patch panel amplifier
exceeds an overrange output, approximately plus/minus 10 volts. power
switch . . . The toggle switch at the panel's lower right applies AC power. | 
