How do transistors amplify signals?

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SUMMARY

Transistors amplify signals by using a small input current to control a larger current drawn from a power supply, resulting in a larger output signal that is a replica of the input. This process is distinct from traditional efficiency calculations, as amplifier efficiency is defined as the output power divided by the total input power from the power supply, which remains less than one. The discussion clarifies that while the output gain can exceed the input gain in terms of power, it does not imply that the efficiency surpasses unity.

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  • Understanding of basic electronics concepts, including current and voltage.
  • Familiarity with transistor operation and types, such as bipolar junction transistors (BJTs) and field-effect transistors (FETs).
  • Knowledge of power supply principles and how they relate to signal amplification.
  • Basic grasp of efficiency calculations in electronic circuits.
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  • Learn about amplifier classes (A, B, AB, C) and their efficiency characteristics.
  • Study the concept of power supply design and its impact on amplifier performance.
  • Explore the differences between voltage gain and power gain in electronic circuits.
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d logician
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i have no idea how transistors amplify ...how can the output gain be greater than the input gain ? ...efficiency is output/input which can never be greater than one, right?
 
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sorry how can output be greater than input ...not output gain greater than input gain
 
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Do you understand how a relay works? It uses low voltage and low current to switch a higher voltage and higher current. Transistors are similar.

In the case of transistors, a small input current controls the amount of current drawn from a power supply to create a much larger replica of itself at the output. Efficiency in the case of amplifiers is not the output signal divided by the input signal but the output power divided by the total input power from the power supply. The power supply always supplies more power than is available at the output so the efficiency is still always less than one.
 

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