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TRANSISTORS BIPOLAR TRANSISTORS Basically, this name transistor is made up of two terms “transfer-of –resistor” because its resistance transfers from one value to other value depending on its bias. In other words the current through transistor is controlled by the bias. Bipolar means both, holes and electrons take part in carrying the current through transistor therefore they are called as bipolar transistors. The transistor also is a P-N device but with two P-N junctions and three terminals 1) Emitter –that emits electrons 2) Base-which controls this electron flow 3) Collector –that collects these electrons. There are two basic types of bipolar transistors i) NPN transistor and ii) PNP transistor. Fig. shows their structure and symbol. Arrow –out indicates NPN and arrow – in is PNP.
TRANSISTORS
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