Operational Amplifiers

Objectives:
Create a circuit that contains an inverting operational amplifier that is being delivered between 0 to 1V and a current of 1mA. The operational amplifier must also deliver 10V to a micro-controller in order for the controller to function.

Step 1A

We can use ohms law to calculate Ri

V = iRi = 1/.001

Ri = 1,000 Ohms

Step 1B

Using nodal analysis we can  then relate Ri to Rf

                                      

The power being supplied will be 12 volts so we have to make an adjustment to the circuit as shown below with a 10K pot to allow for a flow of 1V.

Additionally using nodal analysis we can calculate the value for Rx

(12-1)/Rx = (1/10,000) +1 /1000)

Rx = 10,000 Ohms

To simplify analysis we are requested to reduce the circuit, and are requested to figure the resistance if the 1/4 W resistor was used at half its rated power.

1300 Ohm Resistors are Available

 Now we can calculate Ry

                                                         130 Ohm Resistors are Available

R Thevenin can now be calculated:

R Thevenin is not 20 times less than the Ri, which means it can have a loeading effect on the input circuit 

Rth = 118 Ohms

Ri = 1,000 Ohms

Step 2 

                                                                  Experiment diagram

                                      

                                                       Measured Values for Used Components

Step 3

Conduct experiment, record data, and calculate gain (Vin/Vout). See below:

Data

Conclusion:
The data table illustrates how an op amp can create a gain of a voltage. There are many practical applications that require different voltages in the same circuit and the op amp allows one avoid adding more power supplies