Transistor definition for dummies how to#

The scheme of alternative current voltage of amplifier system with common emitter (OE)Īmplified voltage of the input signal is put between the base and emitter of the transistor, whereas the signal is received between the base and collector after amplification. Voltage amplification of this circuit is close to unity, so the output of the amplifier receives “repeated” voltage from the input hence the second commonly used name of this amplifiers – emitter. I Cmax– the maximums collector current,Īmplified voltage of the input signal is put between the base and collector of the transistor, whereas the signal after amplification is received between collector and emitter.V CE0max– the maximum permissible Base-Emitter forward bias,.V CB0max– the maximum permissible Base-Collector reverse bias,.V EB0max –the maximum permissible Base-Emitter reverse bias,.It is used in digital and pulse circuits. As a switch (valve) – here the transition between saturation region (on) and cutoff (off) is used.Transistor as an amplifier – transistor operating in a forward-active region might be used to construct the system, which will amplify electrical current.These regions of the transistor are commonly used according to need for example: Family of current-voltage characteristics of the bipolar transistor (OB) Family of current-voltage characteristics of the bipolar transistor (OE) Fig. Base current is so large that the collector circuit cannot amplify it β times more.īipolar Transistor – Current-voltage characteristics Fig. Saturation mode – Collector-Emitter Voltage drops to the small amount.Reverse-active mode (inverted mode) – Base-Emitter junction is reverse biased and Base-Collector is forward biased.As a result of these operations, a small current shall flow between the base and emitter allowing greater current to flow between the collector and emitter electrodes. Here, under the impact of the electric field in the depletion region they are attracted to the collector. Carriers injected from the emitter into the base region (float) (the phenomenon of diffusion) into the region of Base-Collector junction region where their concentration is lower). Base-Emitter voltage inject majority carriers from the emitter through the junction to the base – (in N-P-N electrons and in P-N-P holes). Collector current takes a value of β times increased of the base current value. Here, it is worth noting to not exceed the voltage of the junction (silicon or germanium diodes), which could result in the flow of large base current and possible damage to the transistor. Forward-active mode (most often called active mode) – Base-Emitter junction is forward-biased and the Base-Collector junction is reverse-biased.The collector’s current values are very small, Cut-off mode– Base-Emitter junction is not biased at all or it is reverse-biased.Depending on its operation point, transistor might be in four modes of operation: Main feature of bipolar transistors is the possibility to control a high current with usage of small one. Distribution of currents in NPN transistor Bipolar Transistor – Principle of o peration Diode replacement model of PNP transistor Fig. Diode replacement model of NPN transistor Fig. PNP bipolar transistor symbol and the construction of its junctions Fig. NPN bipolar transistor symbol and the construction of its junctions Fig. In this example, two p-n junction forms ( diodes): Base-Emitter (BE) and Base-Collector (BC).įig.

Transistor definition for dummies how to#

If you are a student or simply want to learn how to solve bipolar transistor tasks, please visit this section of our website where you can find a wide variety of electronic tasks.īipolar transistor consists of three semiconductor regions with different types of conductivity: N-P-N or P-N-P. Transistors are used almost everywhere: from amplifiers, generators, power switching systems to computers and more advanced systems. Silicon Si transistors are most often used (Threshold Voltage V T = 0.6 – 0.7V), less common are germanium Ge (V T = 0.2 – 0.3V). Electrodes of the bipolar transistor have the following names: – C – collector, B – base, E – emitter.

There are two types of bipolar transistors: N-P-N transistors and P-N-P transistors. The amplifier is a device, which can control more power with usage of less power. Bipolar transistor – three-ended (three electrodes), current-controlled semiconductor electronic component, which has the ability to amplify the signals of direct current and alternating current, so every transistor belongs to the amplifiers family.