Buchla 200e series, User Manual

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Quad Control Voltage Processor model 256e
25609030
This module offers various sorts of control voltage processing, including
selection, multiplication, addition, scaling, inversion, and non-linear
transformation. Its four sections are identical and independent. A description
of section A follows, and is applicable to sections B, C, and D.
The leftmost knob selects between two input voltages, A1 and A2 . To enable
voltage control of the selection, crank the knob to 0 and apply a selection
voltage to “In Select”. A voltage applied to “In Select” replaces the knob,
performing the following operation:
V
in
= InSel x A2 + (1 – InSel) x A1
Where V
in
is the voltage applied to the transformation matrix. For the
purposes of the present discussion, the ranges of all input voltages and knob
settings are normalized to one. Note that if A1 is unconnected, the input
section simply multiplies InSel and A2.
V
in
is now applied to the transformation matrix, which works as follows:
With no breakpoint specified, 2 LED’s will be illuminated, one on the left; the
other on the right of the display. A press of the switch adds a single
breakpoint, indicated by a third LED somewhere in the display’s center.
With the breakpoint switched off, the following function is executed:
V
out
= V
in
x V
10volts
+ (1 - V
in
) x V
0volts
This is a simple linear transformation of the input voltage. For zero volts input,
the output is set by the knob labeled 0 volts in, and for 10 volts input, by the
knob labeled 10 volts in. Other values are interpolated, and the transfer
function can be represented as a straight line connecting the two endpoints.
The two breakpoint knobs are not operative in this mode.
Now hit the breakpoint switch, and things get more interesting. A breakpoint
LED is illuminated whose location can be set with the two knobs to the right of
the switch. The resultant transfer function is the two segment line connecting
the three points, mathematically represented as:
If V
in
< V
inbp
,
V
out
= (V
in
x V
outbp
) / V
inbp
+ (1 – V
in
/ V
inbp
) V
0volts
If V
in
> V
inpb
,
V
out
= [(V
in
– V
inbp
) V
10volts
+ (1 – V
in
) V
outbp
] / (1 - V
inbp
)