P 6.5-12 The input to the circuit shown in Figure P 6.5-12a is the voltage  .  The output is the voltage .  The voltage  is used to adjust the relationship between the input and the output.

(a) Show that the output of this circuit is related to the input by the equation

 

 

Where a and b are constants that depend on

 

(b) Design the circuit so that its input and output have the relationship specified by the graph shown in Figure P 6.5-12b.

 

../../9eIllustrations/Ch06/c06f091a.eps

../../9eIllustrations/Ch06/c06f091b.eps

Figure P 6.5-12

Annotating the circuit

 

(a) Show that the output of this circuit is related to the input by the equation

 

 

Where a and b are constants that depend on

 

There are two unique  nodes.  The two on the left are electrically connected.  So write a node equation for each the left and the right.

Left

Right

 

This equation leads to

 

 

Plug this into other equation

 

 

 

 

Solve for

 

 

 

So comparing with the equation given

 

So the coefficients are:

 

 

 

(b) Design the circuit so that its input and output have the relationship specified by the graph shown in Figure P 6.5-12b.

 

First find the equation of the line.  Use the two points (-4, 0) and (0, 5)

 

 

 

 

So we have   So we have the two conditions

 

 

 

There are many solutions.  To simplify let’s make the assignment

 

 

The two conditions become

 

 

 

 

 

Again, keep in the k range, but there are many possible answers.

 

Let   Then   and choose  

 

Find a and b

 

 

 

As it should be.  Now find b

 

 

 

 

 

 

 

 

 

One possible answer is

Other answers are possible!

 

 

Please send any comments or questions about this page to ddonovan@nmu.edu

This page last updated on March 17, 2019