ENGR201 Lab 2019 Lab
Lab 7
Name: Humberto Arredondo Perez
Email: harredondoperez@fortlewis.edu

1. Operational Amplifiers

2. Introduction
In this lab students learned basic understanding of operational amplifiers (Figure 1). By seting up differents circuits, students got some skills of the function of op amps and learned how to amplified a signal given by a function generator and were able to use the oscilloscope as well as the power supply for testing.

3. Materials

4. Methods



Figure 1. LM741 OP AMP

Task 1
Students Builded the following circuits (Fugure 2) on a breadboard and filled up the table with the data was observed (Table 1).






Figure 1 Differents circuits use to find Vout
Vp=0V
 I
 II
 III
Vm
 0
 1.93
 1.93
Vp=2.5V
 I
 II
 III
Vm
 0
 2.5
 2.5
Vp=4.5V
 I
 II
 III
Vm
 0
 4.5
 4.5
Vp=6.5V
 I
 II
 III
Vm
 0
 6.5
 6.5
Table 1 Results show Vp = Vm due to the negative feedback

Task 2
Maximum supply voltage and the input voltage that can be applied to the Op Amp LM741



Figure 3. Max Supply and Input Voltage


Task 3
A R1=5k resistor and a potentiometer (100k) was connected to an Op Amp. Powered up to OpAmp using +9V/-9V instead of 9V/GND. Connected the input signal to a sine wave (1k Hz, 2V Vpp). Changed the resistance of the potentiometer while looking at the scope (Table 4 and Table 5).







Table 4 circuits for task 3


Table 5. Graph observed from the simulation of the circuitss from Table 4 (sine wave, 1 kH, 2V Vpp)


Task 4

Change the -9V supply back to GND. Use a voltage divider to provide 4.5 DC 'bias voltage' to the non-inverting terminal.
Table 6 shows the task 4 from 0 to 9 v and a base of 4.5v



Task 5

Inject a triagle wave (10V Vpp, 1 kHz) into the inverting terminal.


Table 7 shows task 5 triangle wave.


Discussion

In this lab students learned about operational amplifiers, how toy behave, how to calculate the gain and experiment with inverting options.