transistor as a switch

Using a transistor as a switch is the simplest application of the device. A transistor can be extensively used for switching operations either for opening or closing of a circuit. Meanwhile, the basic concept behind the operation of a transistor as a switch relies on its mode of operation. Generally, the low voltage DC is turned on or off by transistors in this mode.

Both PNP and NPN transistors can be utilized as switches. A basic terminal transistor can be handled differently from a signal amplifier by biasing both NPN and PNP bipolar transistors by an “ON / OFF” static switch. One of the main uses of the transistor to transform a DC signal “On” or “OFF” is solid-state switches. Some devices, including LEDs, only require several milliamperes of DC voltages at the logical level and can be directly controlled via the logical gate output. High-power devices such as generators, solenoids or lamps usually need more power to use transistor switches than the usual logic gate.

As one of the significant semiconductor devices, a transistor has found use in enormous electronic applications such as embedded systems, digital circuits, and control systems. In both digital and analog domains transistors are extensively used for different application usage like amplification, logic operations, switching, and so on.

This article mainly concentrates and gives a brief explanation of the transistor as a switch. The Bipolar Junction Transistor or simply BJT is a three-layer, three-terminal and two junction semiconductor device. Almost in many of the applications, these transistors are used for two basic functions such as switching and amplification.

The name bipolar indicates that two types of charge carriers are involved in the working of a BJT. These two charge carriers are holes and electrons where holes are positive charge carriers and electrons are negative charge carriers.