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Darlington Pair » Electronics » Basic Circuits » Darlington Pair » Let's go... » Experiment 1 - Amplifier

Experiment 1 - The Transistor as Amplifier

Build the circuit shown, where the transistor is in a collector circuit. The high-resistance resistor R1 provides the weak signal as it allows only a very small current into the base of the transistor.

Amplifier circuit of a weak signal with a transistor. (Enlarge)

As you are turning the potentiometer P1 over a wide area you can turn without the LED light up completely and the transistor saturates.

Circuit diagram of an amplifier of a weak signal with a transistor.

From the experiments on "Transistor Basic Circuits" you know that a typicalBC547B transistor has the following characteristics....

  • a gain β = 100 - 300
  • a base-emitter voltage VBE = 0.65 V

But now you observe the changes with a Darlington Pair...