In this note, we are discussing about a topic that How Transistor Works as an Amplifier. Also talking about circuit diagram, working principle and uses. Welcome to Poly Notes Hub. a leading website for Diploma Engineering Notes or Polytechnic Notes Syllabus-Wise.
Author Name: Arun Paul.
What is Transistor Amplifier ?
An electrical device that employs transistors to boost an electrical signal’s amplitude or intensity is called a transistor amplifier. It functions by taking a weak input signal and amplifying it at the output while maintaining all of its fundamental properties. The essential elements in these circuits are transistors, which can function as amplifiers or switches. For speakers, antennas, and other output devices, amplifiers help enhance signals to acceptable levels in a variety of electronic devices, including radios, TVs, and audio systems.
Circuit Diagram of Transistor Amplifier
Below shows the basic circuit diagram of Transistor Amplifier –
Working Principle
This is how Transistor Works as an Amplifier works –
A transistor raises the strength of a weak signal and thus acts as an amplifier. The above Figure shows the basic circuit of a transistor amplifier. The weak signal is applied between the emitter-base junction and the output is taken across the load RC connected in the collector circuit. To achieve faithful amplification, the input circuit should always remain forward-biased. To do so, a D.C. voltage VEE is applied in the input circuit in addition to the signal as shown. The D.C. voltage is known as bias voltage and its magnitude is such that it always keeps the input circuit forward-biased regardless of the polarity of the signal.
As the input circuit has low resistance, a small change in signal voltage causes an appreciable change in emitter current. This causes almost the same change in collector current due to transistor action. The collector current following through a high load resistance RC produces a large voltage across it. Thus, a weak signal applied in the input circuit appears in the amplified form in the collector circuit. It is in this way that a transistor acts as an amplifier.
Applications
Below we listed some applications of Transistor Amplifier Circuit –
- Used in different kinds of audio equipment like Stereos, Speakers, Earphones etc.
- Used in Medical equipment also.
- Transistor amplifiers are employed in motor control circuits, voltage regulators, and power supplies to manage and control the flow of electrical power.
