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How does a NPN transistor work?
The NPN transistor is designed to pass electrons from the emitter to the collector (so conventional current flows from collector to emitter). The emitter “emits” electrons into the base, which controls the number of electrons the emitter emits.
How transistors work in a circuit?
A transistor works when the electrons and the holes start moving across the two junctions between the n-type and p-type silicon. The small current that we turn on at the base makes a big current flow between the emitter and the collector. So the base current switches the whole transistor on and off.
What is the purpose of a NPN transistor?
Another common application for NPN transistors is to use them as an amplifier, in which a small increase in the input voltage induces a large change in the output voltage. NPN transistors are used for this purpose in almost all phones electronic devices in which sound amplification or reproduction is required.
Why do we use NPN transistor?
NPN transistors are used when you want to sink a current; i.e. current flows into the collector. PNP transistors are used when you want to source a current; i.e current flows out of the collector. As a result of this, NPN transistors usually have their emitter connected to the low side of the supply.
How do NPN and PNP transistors operate?
The operation of the PNP and NPN transistors mainly utilizes holes and electrons. These transistors can be used as amplifiers, switches and oscillators. In PNP transistor, the majority charge carriers are holes, where in NPN the majority charge carriers are electrons.
What are the working principles of transistor?
Working Principle of Transistors. When no voltage is applied across the transistor, diffusion of free electrons across the junctions produces two depletion layers . For each depletion layer, the barrier potential is about 0.7 V at 25°C for a silicon transistor and 0.3 V for a germanium transistor.