Experiment 3 - Base-Emitter Voltage of the Darlington Pair

In this and the next experiment you examine more closely the Darlington pair. First you look at one of the most important characteristics of each transistor circuit, the base-emitter voltage.

Build the circuit shown. With the multimeter you measure the voltage between the base of transistor T1 and the emitter of transistor T2. Measuring the voltage UBE of a Darlington pair. (Enlarge)

Circuit diagram measuring the voltage UBE of a Darlington pair.

Turning the potentometer P1 until the Darlington pair is fully saturated, you measure a base-emitter voltage of...

U_BE = 1.30 V

This value is twice as high as of a single transistor. This is a disadvantage of the Darlington pair.

But what about the gain of a Darlington pair?