Elenco 130-in-1 Electronics Playground - Manual (Page 83)

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Did you know that a transistor alters its
characteristics according to the temperature? This
experiment will show you how temperature affects
transistor action.
View the schematic. The NPN transistor acts as a
pulse oscillator. The 22k
Ω resistor and the PNP
transistor control the voltage applied to its base. The
transistor’s base current and collector current vary
with the temperature.
Build this experiment and you will hear a sound from
the speaker. Modify the 50k
Ω control so that the
sound is low or a series of pulses.
Hold the PNP transistor between your fingers to
warm it up. As the transistor temperature increases
you will hear the tone become higher.
Notes:
EXPERIMENT #65: HEAT-SENSITIVE OSCILLATOR
Schematic
Wiring Sequence:
1-29
2-30
3-101-103
4-26-41-119
5-47-104
27-81
120-28-48
40-82
42-85
46-102-86