Another transistor amplifier problem

[poala999]

http://www.vcaa.vic.edu.au/vce/studies/physics/pastexams/physicspilot12004.pdf

Page 13. AC signal on CRO. Answer is B. How the heck do they do that?

Relevant information is on page before.

Love peoples explanations but please try to keep it simple.

Sorry if i seem direct.

I don't understand why it is centred around 12V, and the cut off points.

Sub-question...? what would this look lke if there was a capictor on the Vout.

 

[poala999]

not sure if I'm allowed to post my msn address but here it is k.c@internode.on.net, add me for a chat if need be. Thanks a million!

 

[m2003]

It is not uncommon for students to struggle with transistor amplifier problems, especially when dealing with AC signals and CRO measurements. It is important to understand the basics of transistor amplifiers before attempting to solve problems like this.

The first step is to understand the circuit diagram given on page 13. The circuit consists of a transistor, a resistor, a capacitor, and a source voltage of 12V. The AC signal is applied to the base of the transistor, and the output voltage is measured across the resistor.

To answer the question, we need to understand how the transistor amplifies the AC signal. This can be done by analyzing the circuit using Kirchhoff's laws. The transistor acts as a current amplifier, allowing a larger output current to flow through the resistor than the input current at the base. This is due to the transistor's ability to control the flow of current through its collector-emitter path.

In this specific problem, the DC voltage of 12V is used to bias the transistor in the active region, meaning it is not fully saturated or cut off. This allows for the transistor to amplify the AC signal without distortion.

The cut off points refer to the maximum and minimum voltage values that the transistor can handle before it enters the saturation or cut off regions. These points are important to consider when designing a transistor amplifier circuit to ensure it operates within safe and desired levels.

As for the sub-question, if a capacitor was added on the output voltage (Vout), it would act as a high-pass filter, allowing only high-frequency signals to pass through. This would result in a smoothed out output signal, reducing any noise or fluctuations in the signal.

In summary, understanding the basics of transistor amplifiers and analyzing the circuit using Kirchhoff's laws can help solve problems like this. It is also important to consider the biasing of the transistor and its cut off points to ensure proper operation.