Engineering Class
bobtruong242
engr_1201_final_project_om_amp.docx
ENGR 1201
Final Project
Operational Amplifier
Jennifer Medina
Bao Tr
May 8, 2015
What is an Operational Amplifier?
An operational amplifier is fundamentally a voltage amplifying device designed to be used with external feedback components such as resistors and capacitors between its output and input terminals. These feedback components determine the resulting function or operation of the amplifier and by virtue of the different feedback configurations whether resistive, capacitive or both, the amplifier can perform a variety of different operations, giving rise to its name of Operational Amplifier. In our project, we used three terminal device which consists of two high impedance inputs, one called inverting input that is marked as a negative or a minus (-), and the other one that is positive that is called non-inverting input that is marked with a plus or positive sign (+). The third terminal represent the Operational Amplifier output port which can both sink either voltage or a current in our case we used voltage.
Objective:
The objective of this project is to understand exactly how a basic operational amplifiers works. Also, to be able to read basic electrical circuits.
Apparatus used:
Resistors, connecting wires, batteries, digital oscilloscope, voltmeter, an electronic learning lab, speaker, connecting cables, DC power supply, capacitors, and a bug.
Concepts
· Voltage – Voltage “in” and Voltage “out”
· Current – Current “in” and Current “out”
· Trans conductance – Voltage “in” and Current “out”
· Trans resistance – Current “in” and Voltage “out”
· Resistor
· Battery
· Ground
· /
· Wave graph
The presented circuit diagrams where the ones use for the project.
Circuit diagram #1
V DD
Vout
Rin
Vin
RF
VDD
Vout
Vin
Rin
RF
Circuit diagram#2
Vin
V out
RF
Rin
AC
source
8
6
3
5
7
2
4
1
Data:
This image we see the actual circuit done in the electronic learning lab. This match exactly with our circuits shown before.
These second images we can see a picture of the oscilloscope proving the theory of operational amplifiers. The yellow waves is the initial signal and the green waves are the output signal. As one can see the yellow is a very small signal compare it to the green one. The green one is inverted and has a larger amplitude, but they both have the same frequency.
In this particular image one can see what happened when we increase the RF (resistance) RF varies that is why it has a cross line in our circuit diagram #2. However, RF is just affecting the output result the input is till will be the same
In this image we increase the Voltage and we reduce the resistor, but because we did this our PK-PK also increases. This still just affect the output, the input still the same and the frequency of both channels is till the same. Something very important that happened while we were doing this part is that we had an interference problem, so we had to change the cables to keep having clear waves. Also, we find out this happened because we did not calibrate the apparatus before using it. However, this would not affect our final results because we were able to solved the problem without any issue.
In this image we can see what happened when you increase the voltage and have a lost of resistance (RF). As a result it give us a bigger amplitude a change of PK-PK, but always with the same amplitude.
In this image we can see what happened when there is a drop of both resistors Rin and RF. Its is clear to see that the second channel goes out of the screen this is due to the loose or resistant on resistor RF and also because proves that our project was successful. Stating that there is a small signal in the input and there will be a invert signal with a different amplitude, but the same frequency.
This image shows our second part of the project. In this part as one can see we decide to connect a little speaker to the circuit. As a result, when we increase the voltage in the power supply the speaker gave us different sounds. As the voltage increases the sound was thinner, but as the resistor RF gain resistance the sound was louder, and when it loose resistance its sound reduce. Another important thing we did while doing this part of the project was to measured how sensitive our ouditivity is this by ……..
Here we can see the input and the output waves in the oscilloscope the green one is the output and the blue is the input this image proves our successes in this project. We connect the speaker and from a small signal we had a bigger and invert signal giving us sounds.
As result of the data took and the observation on the project we can say that it is clear to us to understand how basic operational amplifiers work. Also, we were able to prove how it works and understand how to read a circuit and do the circuit. However, we did have errors while dong our project, but since there is no an actual data to compare we cannot calculate our percentage of error.
Conclusion
