Types of Bidirectional Transistors

Microchips contain microscopic transistors.

Bidirectional transistors are also known as BJTs, or bipolar junction transistors. They are primarily used in devices, such as radio receivers, that place heavy electrical loads on components. BJTs divide into two varieties: NPN and PNP.

Transistors Defined

Transistors are digital switches. They allow electricity to flow from one terminal to the other only when a third "trigger" terminal detects an electrical charge. Because most microchips cannot handle heavy charges, stand-alone transistors are used in high-power circuits.

NPN Transistors

NPN transistors are made of p-type silicon surrounded by n-type silicon. NPN transistors activate when there's a positive charge on the collector and a negative one on the emitter. A positive charge applied to the trigger terminal opens the transistor.

PNP Transistors

PNP transistors are the mirror opposite of NPN's. PNP transistors are made of n-type silicon surrounded by p-type. They work similarly to NPN's, but a negative charge must be applied to the collector and a positive charge to the emitter.

References

• Diodes.com: Bipolar Transistors or MOSFETS?
• PCMag: Bipolar Transistors