Working principle of 3-pole tube

The working principle of a transistor: Apply a positive voltage to the emitter through the base to forward bias the PN junction, and electrons are injected from the emitter into the base. The electrons in the base diffuse to the base-collector junction and are attracted by the positive voltage at the collector. The base current controls the collector current, creating an amplification effect (small changes in base current lead to large changes in collector current).

The working principle of the triode

The triode is an electronic component consisting of three terminals: base pole, collector and emitter. It is widely used in electronic circuits as amplifiers, switches and logic gates.

Working principle

The working principle of the transistor is based on the characteristics of the PN junction. There are two basic types of transistors: NPN and PNP, which are each composed of two different PN structures. For NPN transistors, the working principle is as follows:

1. Closed base-emitter loop: When a forward voltage is applied between the base and emitter, the base The PN junction between the emitter and the emitter is forward biased. This allows electrons to be injected from the emitter into the base.
2. Base current controls collector current: Electrons injected from the base diffuse to the base-collector junction and are attracted by the positive voltage of the collector. Most of these electrons pass through the base-collector junction and enter the collector.
3. Amplification effect: The base current is very small, but the collector current can be controlled. This means that a small change in the base leads to a much larger change in the collector. This amplification effect is called the amplification factor or gain of the triode.

The working principle of the PNP transistor is similar, except that the bias direction of the PN junction is opposite.

Applications

The amplification effect of triodes makes them very useful in many electronic applications, including:

• Amplifiers
• Switch
• Logic Gate
• Oscillator
• Modulator

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