Transistor

A transistor is an electronic piece consisting of semiconducting materials, having three legs, the semiconducting material is similar on the ends, and differs in the middle, and is considered one of the most important inventions in the field of electronics, where it replaced the large size vacuum valves, and the bipolar. Transistor is divided ( Bipolar Junction Transistor) into two types, PNP and NPN, which are the most common and used

The terminals of the transistor have three terminals:

the base B, the collector C, and the emitter E.

Emitter: It is a side terminal on which the electrical charges are concentrated, thus generating electrons and generating electrical current and symbolized by the letter (E).

Base: is the middle end between the radiator and the collector, which controls the direction and amount of electrical current and is symbolized by the letter (B).

Collector: It is another side end, unlike the emitter, it is less concentrated for electrical charges, which in turn collect the current coming from the emitter, and its symbol (E).

The transistor uses the transistor as a mechanical key to separate the current from the circuit, thus turning off the circuit or device, so if we take an example of a simple electrical circuit consisting of a source of voltage, connected with a resistance, and the resistance connected to the switch to the grounding or ground, when the switch is open the voltage is at the ends of the resistance Equal to the voltage of the source, that is, it is not present in the voltage, therefore the current does not flow, but if the switch is closed, the voltage on the end of the resistance connected to the switch becomes zero, that is, it forms a potential difference around the ends of the resistance, then the current will flow.

In the same principle, the transistor works, when the current at the base (Ib) is equal to zero, the transistor becomes a high resistance, preventing the flow of current through it, so an open circuit is formed, so no voltage difference is formed, and the transistor is an open switch, but when the base current is in the saturation stage (Isat), a current passes from the collector to the emitter connected to the ground, so it works to connect the circuit, so a voltage is formed between the two ends of the resistance and the current is flowing, and so the transistor is a closed switch, and the necessary values ​​of the circuit can be calculated in theory based on the following equations:

V (Rc) = Ice * Rc V (Rc) + V (ce) = Vcc

Where,

 VRc: is the voltage difference between the two ends of the resistance connected to the collector.

Ice: the collector and emitter stream.

Vce: voltage difference between the collector and the emitter.

Other uses of the transistor

There are many other uses of the transistor is an essential component in electrical circuits and electronics, the wave or the electromagnetic signal grows in a amplifier. Reflector for electrical signals. Used as an oscillator for signal in high frequency circuits. Merging the signal into the reception circuits, which is called (the national team). Integral of signals in vertical deflection circuits.