R4

2=

R1

R4

4=

R2

R4

3=

R3

Any resistors that will provide the ratios shown above could be used. If the feedback

resistor (R4) is a 12-kilohm resistor, the values of the other resistors would be calculated as

follows:

12 kΩ

2=

R1

2(R1) = 12 kΩ

R1 = 6 kΩ

-------------

12 kΩ

4=

R2

4(R2) = 12 kΩ

R2 = 12 kΩ

-------------

12 kΩ

3=

R3

3(R3) = 12 kΩ

R3 = 4 kΩ

7-90. Figure 7-23 is the schematic diagram of a scaling amplifier with the values from

the previous calculations. To see if the circuit will produce the desired output, calculate the

currents and voltages as done for the previous circuits.

With:

E1 = +12 V

E2 = +3 V

E3 = +8 V