subject: BJT Transistor: A Review Of A Useful Electronic Device [print this page] BJT Transistor: A Review Of A Useful Electronic Device
A bjt transistor (BJT) is an electronic device made by doped semiconductor material and can be made use of in amplifying or switching functions. It is a three-terminal electronic device.
Because electrons and holes are both involved in their operations they are named as such. It was invented in 1948. The word Transistor which is an acronym was derived from the words Transfer Varistor which is used to relate their way of operation in the early days of their development.
During the times when technical achievements were made using the large vacuum tubes, this device made it possible to achieve the same feats .Even though it was small and mechanically rugged it made use of tiny specks of crystalline silicon. This revolution helped in the design and manufacture of inexpensive and lightweight electronic devices which are now taken for granted.
It has a three layer sandwich of doped semiconductor materials which is either P-N-P or N-P-N. There is a specific name for each layer and it has a wire contact of a circuit for connection. It works as current regulators controlled by current. The controlled main current flows from collector to emitter, or vice versa based on the type of transistor it is.
The small current which controls the main current flow from base to emitter or vice versa based on the type of transistor it is. The main operation of the two transistors is the same with only the difference in their biasing and polarity of power supply .
It is called bipolar as the main flow of electrons happens between two types of semiconductor material which are P and N. The controlled current and controlling current blend together through the emitter wire always and their electrons move against the transistor's arrow. The main rule of transistors is that all currents must flow in the proper directions so that the machines work as a current regulator.
The controlling current is normally called as the base current as it is the only current that flows through the transistor's base wire. On the other hand, the controlled current is called as the collector current as it is the only current that flows into the collector wire.
In conclusion, it is a current regulating electronic device which controls the amount of current going through it in proportion to the amount of voltage biased applied to their base terminal behaving like a current-controlled switch.
