Transistor Amplifier Concepts and Calculations

This video tutorial explains how to calculate the voltage gain of an NPN transistor amplifier. It covers the formula for voltage gain, which involves the AC collector resistance and the sum of the AC emitter resistance and the emitter resistor. The tutorial provides a step-by-step guide to calculating base and emitter currents, using example problems to illustrate the process. It also discusses the impact of a voltage divider bias circuit and the role of a bypass capacitor in increasing voltage gain. The concept of a swamped amplifier is introduced, highlighting its ability to stabilize gain.

What is the formula for calculating the voltage gain of an NPN transistor amplifier?

• AC collector resistance divided by the sum of AC emitter resistance and emitter resistor

• AC emitter resistance divided by the sum of AC collector resistance and emitter resistor

• Emitter resistor divided by the sum of AC collector resistance and AC emitter resistance

• AC collector resistance multiplied by the sum of AC emitter resistance and emitter resistor

How is the base current calculated in a voltage divider circuit?

• Vcc plus Vbe divided by the sum of Rb and Re

• Vcc times R1 over the sum of R2 and R1 minus Vbe divided by R1 times R2 over R2 plus R1

• Vcc minus Vbe divided by the sum of Rb and Re

• Vcc times R2 over the sum of R1 and R2 minus Vbe divided by R2 times R1 over R1 plus R2

What is the relationship between AC emitter resistance and emitter current?

• Exponentially proportional

• Directly proportional

• Inversely proportional

• Unrelated

How is the voltage gain approximated when the load resistance is very high?

• RE multiplied by RC

• RE divided by RC

• RC divided by RE

• RC multiplied by RE

In the example problem, what is the value of the load resistor?

• 510 ohms

• 10 kilo ohms

• 220 kilo ohms

• 47 kilo ohms

In the example problem, what is the calculated base current?

• 0.017 milliamps

• 3.417 milliamps

• 7.32 milliamps

• 0.0754 milliamps

What effect does a bypass capacitor have on the voltage gain of a circuit?

• Decreases the voltage gain

• Has no effect on the voltage gain

• Increases the voltage gain by decreasing AC emitter resistance

• Increases the voltage gain by increasing AC emitter resistance

What is the purpose of a swamped amplifier?

• To decrease the voltage gain

• To eliminate the need for a bypass capacitor

• To stabilize the voltage gain

• To increase the voltage gain significantly

What happens to the voltage gain if the AC emitter resistance decreases?

• The voltage gain decreases

• The voltage gain remains the same

• The voltage gain increases

• The voltage gain becomes zero

What is the effect of adding a bypass capacitor on the AC emitter resistance?

• It increases the AC emitter resistance

• It doubles the AC emitter resistance

• It decreases the AC emitter resistance

• It has no effect on the AC emitter resistance