1. Group Members: Forrest Duplantier & Bach Nguyen
Professor George Durant
ET 225-01
Southeastern Louisiana University
December 10, 2015
Amplifier Project

2. I. Abstract
The term amplifier come from the Latin word ‘amplificare’, to enlarge or to expand.
Amplifiers or amps are electronic devices that can increase the power of a signal. The first
electronic device that can amplify a signal was the Audion(triode) vacuum tube, invented by Lee
De Forest, a Yale PhD graduate. By adding a control grid to Fleming’s two-element diode tube,
create the three-element vacuum tube used as an audio amplifier and oscillator for radio wave
generation. His first patented product was the improvement from Ruhmer and Bell with his
vacuum tube, he created a variable density sound on films process. For the next 50 years, the
vacuum tube was the only device that could amplify. This design of amplifiers didn’t change
until the invention of transistors. Instead of using triodes vacuum tubes, transistors were used for
most of the modern amplifiers.
II. Introduction
The most common usage for amplifiers are in speakers, audio amplifiers, home stereo or PA
systems. Bipolar junction transistors (BJTs) and metal oxide semiconductor field-effect
transistors (MOSFETs) are most common in modern transistors. In this project, we designed a
simple signal amplifiers using a bipolar junction transistor to amplify a 1 Hz signal required for
the project.
III. Objective
Our objective that we would like to achieve is to successfully design and adjust the amount
of resistance to precisely. By doing this we can achieve more understanding of amplifiers and
transistors using our knowledge that we have acquire in ET 225.
IV. Materials
- 3x10K Ω POTs - 2x1K Ω POTs

3. - Jump wires
- 1xBipolar Junction Transistors
- 2xCapacitors 100µF
- 1xBreadboard
- 1x9V Power Source
- Elvis Machine
- Oscillator
- Signal Generator
V. Schematic
VI. Project’s Calculation
INPUTS CALCULATIONS
R1 2495 Ω mag Av= 4.9979

4. R2 1757Ω Vb= 3.718956 V
Rc 714Ω Rb = 1030.977Ω
Re1 142.86Ω Ic = 0.004193A
Re2 568.44Ω r'e = 5.962421Ω
Vcc 9V Zit= 33485.04Ω
βdc 200 Zis= 1000.182Ω
βac 225 Ib = 2.1E-05A
Q Point 3V Vce = 3.008908V
VII. Results
1. Peak input Voltage = 200 mV
2. Peak output Voltage(without the 1K Ω resistor) = 1000 mV
3. The value of measured Vce = 2.9 V & value of measured Ic = 3.78 mA. Compare to the
calculated counterpart Vce=3.0089V & Ic = 4.193 mA. The percentage error for Vce is
10% and for Ic is 9%
4. The gain is 5 times
VIII. Conclusion
We have successfully demonstrated and understand the project in amplifying 5 times of the
input voltage. Our measured Vce and Ic are a little smaller than the one we are expecting to get
from our calculations. But the amount of differences is under 10% which is neglect able. The
sources of errors could be in our equipment, the human factor in experimental and the parts and
the transistors is not perfectly measured by the Elvis machine.
References
"Amplifier." Wikipedia. Wikimedia Foundation, n.d. Web. 01 Dec. 2015.
Adam, Mike. "Audio Engineering Society." AES San Francisco 2012 » Historical Event H3:
Lee De Forest: The Man Who Invented the Amplifier. AES, n.d. Web. 01 Dec. 2015.