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(~
Prepare a table of values for the function to be generated
(Figure 20a).
The function (for a Plus VDFG) can be arbitrarily
specified at twelve points
XU,
Xl' X
2
, ••• XII.
Of these,
(~
(~
(~
(~
\
the ten internal points are called breakpoints (corners) and
the other two are endpoints. We should pick Xo
=
0, and normally
XII
=
+10 volts.
No two of these points should be closer
to-
gether than 0.2 volt.
These values should be selected from a
graph of the function to occur at locations on the curve near
important points of inflection and other areas requiring the
most accurate delineation.
If the patching arrangement of
Figure l8a is used, set the attenuators (1 through 12) accurately
to the twelve values of X specified in the table.
Be sure to
ground the low end of even numbered pots 2 through 12.
Place
the computer in the reset mode, and slide the tray containing
the 16.304 Plus VDFG forward.
Set all breakpoint pots fully clockwise (this means all break-
points are close to +10 volts).
Place the function switch in
the center position.
Ground the input to amplifier 14.
Rotate slope pot I fully clockwise.
Rotate slope pot 2 fully
counter-clockwise, and continue alternating the slope pots in
this manner.
This step helps prevent amplifier overload and
aids in identifying the breakpoints during the setup procedure.
Set the output (amplifier 16) approximately to zero by adjusting
the PARALLAX potentiometer.
Set the input (amplifier 14) to +1 volt.
Set the output (ampli-
fier 16) approximately to zero with the CENTRAL SLOPE potenti-
ometer.
Steps
(~
and
(~
above are performed simply to help prevent amplifier overload during
the remaining steps.
(1)
If the patching arrangement of Figure 19a is used, connect the
input of amplifier 14 to the wiper of pot 1 with the long patch-
cord.
If the method of Figure 19b is.used, adjust pot I to the
correct coefficient using the
NULL
POT.
(B)
Read the output of amplifier 17 with the voltmeter set to
the .3 volt range.
The reading should be close to zero, al-
though the precise value is not critical.
(£0
Place the function switch in the UP position, and adjust pot 14
until the voltmeter reading decreases to zero.
To avoid over-
loading the meter (in the .3 volt range), it is advisable to set
pot 14 to approximately .500 before closing the function switch.
The first breakpoint is now located close to +10 volts and we
want to relocate it at Xl (the desired first breakpoint).
41
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