PNP Bipolar Junction Transistor (BJT)

PNP Bipolar Junction Transistors (BJTs) behave like NPN BJTs, but with opposite polarities. NPN BJTs are usually studied before PNP so I will be assuming that you already understand the basic BJT principles.

2N3906 PNP bipolar junction transistor BJT schematic symbol and pin layout diagram by electronzap electronzapdotcom
2N3906 PNP bipolar junction transistor BJT schematic symbol and pin layout diagram by electronzap electronzapdotcom

Quick circuits:

Basics

Bipolar junction transistor basics diagram by electronzap electronzapdotcom
Bipolar junction transistor basics diagram by electronzap electronzapdotcom
  • Emitter more positive than collector. So emitter side of schematic symbol is usually, but not always, higher up than collector.
  • 2N3906 in TO-92 package is a very common PNP BJT.
  • When you let a certain amount of current flow from PNP emitter to base, then the transistor will let a large multiple amount of current flow from emitter to collector. If it has a gain of 10 (which would be extremely low), then for every 1mA of current from emitter to base, there would be
  • Most BJTs have a gain in the low hundreds but also keep n mind that actual gain varies with current and voltages. Most of the time you just select a BJT that has more gain than you need. Always consult the datasheet for specifics of the particular component you are using.

PNP transistor switch circuit

Clicking the diagram below brings you to a page that explains the diagram in more detail.

Basic electronics circuit fragments and simple circuits 7 PNP Bipolar Junction Transistor BJT Switch and capacitor fade off diagram by electronzap electronzapdotcom
Basic electronics circuit fragments and simple circuits 7 PNP Bipolar Junction Transistor BJT Switch and capacitor fade off diagram by electronzap electronzapdotcom

Electronics course 9 PNP Bipolar Junction Transistor BJT switch plus capacitor fade off

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