Ep 8. Transistors as Amplifiers

Understanding Modern Electronics is a well-known television show that is all about demystifying complex electronics. Season 1 episode 8 titled "Transistors as Amplifiers" explores the concept of using transistors to boost electrical signals.

The episode begins by introducing viewers to the role of amplifiers in electronics. Amplifiers take an input signal and increase its voltage, current, or power, without significantly altering its waveform. They play a crucial role in modern-day electronic devices, from radios and televisions to computers and smartphones.

To understand how amplifiers work, the host and a team of experts delve into the theory behind semiconductor materials. They explain how a semiconductor material can either allow or hinder the flow of electricity based on its doping mechanism. When two semiconductor materials of differing doping mechanisms are combined, a p-n junction is formed, which can be exploited to create a transistor.

The experts then take viewers through the different types of transistors, starting with the bipolar junction transistor (BJT) and moving on to the field-effect transistor (FET). They explain the differences between these two types and highlight some of their unique features. For instance, BJTs are more suited to applications requiring higher gain, while FETs are better suited to high input impedance applications.

Next, the episode delves into the common-emitter configuration of a transistor, which is one of the most popular amplifier configurations. The experts show how a small AC signal can be applied to the base of a BJT and amplified many times by passing through the transistor's collector and emitter circuits. They also explain how the voltage gain of an amplifier is measured and how it can be increased by biasing the transistor correctly.

The episode goes on to explain how FETs can also be used as amplifiers and highlights some of the differences between BJT and FET amplifier circuits. For example, FETs feature a high input impedance, which means they do not draw much current, making them ideal for use in battery-powered devices.

The experts also explain how amplifiers can be combined to create multi-stage amplifiers or amplifier circuits with feedback. They discuss some of the benefits and drawbacks of each design and highlight some of the common applications.

Throughout the episode, the host and experts use practical demonstrations to help viewers understand the concepts taught. They show how to construct a simple BJT amplifier circuit and measure its voltage gain. They also demonstrate how to bias a FET transistor and show how to measure its output characteristics.

In summary, "Transistors as Amplifiers" is an educational episode that takes viewers through the principles of using transistors to amplify electrical signals. It teaches viewers about the different types of transistors, the common-emitter configuration, and how amplifiers can be combined to create complex circuits. Through practical demonstrations and clear explanations, viewers come away with a deeper understanding of this critical aspect of modern electronics.