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Adjustable Slope and Zero Point Linear Modification Circuit

IP.com Disclosure Number: IPCOM000035233D
Original Publication Date: 1989-Jun-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 4 page(s) / 56K

Publishing Venue

IBM

Related People

Hoaby, SE: AUTHOR

Abstract

This circuit (which is shown in Fig. 3) can modify a voltage described by the function Vo'(x) = m'x + b', to that of another voltage function described by Vout(x) = Mx + B.

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Adjustable Slope and Zero Point Linear Modification Circuit

This circuit (which is shown in Fig. 3) can modify a voltage described by the function Vo'(x) = m'x + b', to that of another voltage function described by Vout(x) = Mx + B.

The application for which this circuit is suitable requires modifying the output voltage of a probe so that it may be compared directly with the output voltage of a different probe. The outputs of the two

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probes, the actual of one and the modified of the other, may then be fed into units containing two vertical neon displays. If the displays show an equal reading for the two columns, the probes are measuring equal amounts. The displays provide a quick visual inspection.

The M and B portions of the Fig. 3 circuit are adjustable and are designed to allow for variations in the probes and other variations specific to the application. This feature allows great flexibility in application.

Referring to Figs. 1 and 2, showing the outputs of the two probes, this circuit converts the bently probe output such that line CD will be transformed exactly to line AB of the transducer probe. Note that both cover a range of 40 mils, thus only the voltages change.

This circuit produces the same voltage for the same measurement by two probes' from different manufacturers. The probes outputs may be fed into a SIGMACOLUMN display, which contains two vertical neon tubes side by side, one probe for each neon tube. When the heights of the neon displays are the same, then the measurements are the same.

To accomplish this requires modifying one of the probe outputs, so that its readings match that of the other probe. Figs. 1 and 2 show the two probe outputs. The output of the Bently probe in Fig. 2 is the voltage that may be modified. It may be modified by the Fig. 3 circuit to exactly overlay the voltage of Fig. 1.

In the theory of operation of the Fig. 3 circuit, any linear equation can be described by y = mx + b. The voltage to be modified is in the following form: The original or non-modified voltage: Vo'= m'x + b' , m' = slope of the voltage x = the independent variable b' = offset voltage, Vo when x=0 Vo'= output voltage

To produce the modification to the voltage such that it will match a second linear voltage, the voltage after modification must still retain the y = mx + b form. The desired voltage after modification: Vo"= m"x + b" , m" = slope of the voltage x = the independent variable b" = offset voltage, Vo when x=0 Vo"= output voltage

When Vo' is fed into a circuit that does an -mx + b function, then Vout of the circuit would be: Vout = -Mx + B = -M(Vo') + B

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Replacing Vo' with its equivalent and rearranging of terms yields: Vout = - M(m'x + b') + B = -Mm'x + -Mb' + B = -Mm'x + (-Mb' + B)

Since the terms M, m, B, and b are constants, the equation is now of the form desired, Vo" = m"x + b", where m" = -Mm' b" = -Mb' + B The variable in the equation is thus x, and Vout = Vout(x).

In the Fig....