Elenco Basic Electronic Experiments - Manual (Page 29)

EXPERIMENT #16: THE SUBSTITUTE
Look again at the water pipe analogy for the transistor, the lever pivot:
What would happen if the base and collector were connected together? Once there is enough pressure to overcome the
spring in check valve DE (0.7V) there would be only slight resistance and no current gain. This situation should sound
familiar since this is exactly how a diode operates. When the base and collector of a transistor are connected together the
transistor becomes a diode.
Connect the circuit and press the switch, the LED lights. This is the same circuit as Experiment 12, One-Way Current. This
demonstrates how transistors can be substituted for diodes, and this will occur in practice sometimes for manufacturing
reasons.
29
+9V
3.3k
Ω
(Note position
of flat sides)