The only difference is in their biasing and the polarity of the power supply for each type. The principle of operation of NPNs and PNPs is exactly the same. The basic principle of any BJT is to control the current of a third terminal with the voltage between the other two terminals. Here is a list of some classic general-purpose BJTs: In a PNP transistor, however, the current flows from the emitter to the collector ( Fig. In an NPN transistor, the current flows from the collector (C) to the Emitter (E) ( Fig. In a PNP transistor, a positive voltage is given to the emitter terminal to produce current flow from the emitter to collector. We also learnt that the junctions of the bipolar transistor can be biased in one of three different ways Common Base, Common Emitter and Common Collector. In an NPN transistor, a positive voltage is given to the collector terminal to produce a current flow from the collector to the emitter. Reverse Active: Like active mode, the current is proportional to the base current, but flows in reverse.The transistor appears as a near short circuit between the collector and emitter terminals. Saturation: BJT operates in this zone in switching operations.Active: BJT operates in this zone for amplifier circuits because the transistor can act as a fairly linear amplifier.Cutoff: BJT operates in this zone in switching operations.BJTs can operate in different modes depending on the junction bias: The junctions between N and P regions are similar to the junctions in diodes and they can be forward-biased or reverse-biased as well. 2) while the NPN transistor has one P region between two N regions ( Fig. The PNP transistor has one N region between two P regions ( Fig. The semiconductor physics of BJTs will not be discussed here, but it is worth mentioning that a BJT is fabricated with three separately doped regions with two junctions. The positive doping of the base, between emitter and collector, is not concentrated. The Base is responsible for controlling the transistor while the Collector is the positive lead, and Emitter is the negative lead. Type - PNP Collector-Emitter Voltage: -40 V Collector-Base. A transistor is an active device with three terminals, and these three terminals are known as the Emitter (E), the Base (B), and the Collector (C) ( Fig. 2N4250 PNP Transistor 40V - Small Signal TO-92 Case - Lot of 5. BJTs are made of doped materials and can be configured as NPN and PNP. There are two main types of transistor: bipolar junction transistors (BJTs) and field effect transistors (FETs). The structure of a transistor is such that collector current will not flow until there is no source of current at base. The emitter terminal(which is connected to the supply voltage and emits electrons) is like the end connected to the distribution pipe.
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