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8-20
However, the relation between these two pot-settings has a relatively large
interaction; each pot-setting affects both values.
This interaction does
not exist anywhere except at this one Interval.
Setting any other function
value does not disturb previous settings, except for the small secondary
effect of the "diode curvature" which is easily taken care of by "trinnning"
if necessary.
To set the values at the two breakpoints containing zero, first calculate
and tabulate f(O), even though this is not a breakpoint.
The value of f(O)
should be calculated by linear interpolation between the values at the
breakpoints on either side of zero, since the curve is straight over this
interval.
Of course, the interpolation can be done graphically simply by
drawing a line connecting these points.
Once the values have been set at
x
=
0 and at one of the two breakpoints, they should automatically be cor-
rected for the other breakpoint.
Since there is no need for two CENTRAL SLOPE pots in twenty-segment opera-
tion, one of the two pots can be used for a regular breakpoint.
This al-
lows 9 breakpoints to be used on one side of zero, and 10 on the other
o
The operator may put this tenth breakpoint on either side, depending upon
where it is needed most.
As an example, consider the function in Figure
8.8.
This function has three
regions .where it curves rather sharply, separated by regions where it is
relatively straight
o
One. of the curved regions lies in the negative half
of the graph and another in the positive half.
Since the third curved re-
gion lies mostly on the positive side, it appears advisable to put the "ex-
tra" breakpoint on the +DFG.
Hence, BPI on the -DFG is used for the CEN-
TRAL SLOPE, and BPI on the +DFG is used as a regular breakpoint.
The re-
sulting breakpoint tabulation is given in Table
8.4.
Note that the SEGMENT
SELECTOR positions for each segment are given on the figure, as well as in
the table.
In setting the function, first turn all slope switches off for both DFG's
and put the rotary switch at the rear of the drawer to the "20 SEG" posi-
tion.
Address the appropriate output amplifier on the SIGNAL SELECTOR.
Since both DFG's are connected to the first amplifier, it is this amplifier
(the one whose address ends in -6) that should be addressed.
The other out-
put amplifier (the one ending in -7) disconnected from the DFG, and is avail-
able for use as an inverter.
Its slope multiplier switch (the one on the
r'ight) should be set to 10
A quick calculation based on the techniques of
Paragraph
8.4.4
indicates that a slope multiplier of unity is probably ade-
quate for this function;
hence, the slope multiplier switch on the left
should also be set to 1.
Set all breakpoints (positive and negative), but
do not set function values at this time
0
NOTE
Only one SEGMENT SELECTOR should be on at a
time
0
When setting either breakpoints or
function values on one of the DFG's, ensure
that the SEGMENT SELECTOR on the other one is in
the "OFF" position
o
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