# Capacitor in NPN Transistor: Exploring Unknown Theory

• mearom
In summary, the conversation discusses the purpose of a capacitor in a specific circuit and the individual has come up with theories but is unsure of their accuracy. They ask for an explanation and another person points out that more information, such as a complete schematic, is needed to provide an answer. They also mention the use of a capacitor as a high pass filter for local negative feedback in a three stage audio amplifier.
mearom
What's about this? Where a capacitor is between base and collector (NPN). I have formulated some of my own theories (it seems like this is totally unknown of on the internet, and the books I've looked at don't explain it), but I have thought of flaws to all my theories. Can anyone please explain? Thankyou

I think I thought of it

IS it just for feedback, acting as a really high freq filter?

Sometimes you just have to ask to know

Your post tells us basically nothing. You'd need to show us a complete schematic for us to be able to tell you why the capacitor is there.

- Warren

what is cc in vas?

In the voltage amplification stage of a three stage audio amp there is often a coupling capacitor connected to base and collector/ input and output. I think this is as a high pass filter so as to provide local negative feedback

## 1. What is a capacitor in an NPN transistor?

A capacitor in an NPN transistor is a component that stores electrical charge and allows it to be released at a later time. It is used to control the flow of current through the transistor and can also be used to filter out certain frequencies of signals.

## 2. How does a capacitor affect the performance of an NPN transistor?

A capacitor can have a significant impact on the performance of an NPN transistor. It can help stabilize the output by providing a steady source of current, and it can also improve the speed and accuracy of switching between the on and off states.

## 3. What is the role of a capacitor in the amplification process of an NPN transistor?

In the amplification process of an NPN transistor, a capacitor is used to couple the input signal with the base of the transistor. This allows the input signal to control the flow of current through the transistor, resulting in an amplified output signal.

## 4. Can a capacitor be used in both the input and output circuits of an NPN transistor?

Yes, a capacitor can be used in both the input and output circuits of an NPN transistor. In the input circuit, it helps to couple the input signal with the base of the transistor. In the output circuit, it can be used for filtering and smoothing the amplified output signal.

## 5. How do you calculate the capacitance needed for an NPN transistor circuit?

The capacitance needed for an NPN transistor circuit can be calculated by considering the frequency of the input signal, the gain of the transistor, and the desired bandwidth of the output signal. Formulas and equations can be used to determine the appropriate capacitance for a specific circuit design.

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