Experiment 5 - The PNP Transistor

Bipolar junction transistors are available in two versions, the so called NPN and PNP transistors. The difference arises from the internal structure of the transistors and thus they also have different properties.

In recent experiments, you worked with the NPN transistor BC 547 B. Here you get to know the PNP transistor BC 557 B.

The BC 557 B is the complementary transistor to the BC 547 B. To the outside you see no difference. However a PNP transistor is connected differently. Circuit with PNP transistor. (Enlarge) Consider the circuit shown. The base is connected via the resistor R1 to the positive terminal of the battery (+ 9 V). The PNP transistor is closed. (An NPN transistor in this circuit would switch through)

Circuit diagram with PNP transistor.

In the next experiment you switch through the PNP transistor.