Elenco Electronics EP-130, Руководство пользователя

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Now we will build an oscillator using two transistors
connected directly to each other. As you have seen,
there are many ways to make an oscillator. This way
is simple compared to some.
After completing the wiring, press the key. You hear
a beep sound from the speaker. Now rotate the
control. How does it affect sound?
The two transistors cooperate with each other and
act as a single transistor. The NPN transistor
amplifies the signal from the 22k
Ω
resistor and
directs it to the PNP transistor, to obtain a greater
output.
The capacitor determines the frequency of the
oscillation. The project starts with the 0.01
μ
F
capacitor in the circuit but you can experiment with
different value capacitors. The control adjusts the
voltage leading to the base of the NPN transistors. It
changes the tonal quality as well as the frequency.
You should be sure to record your results like a
professional scientist, so you can repeat the
experiment later on. Be sure to observe the polarity
(+ and –) of the electrolytic capacitors.
Notes:
EXPERIMENT #63: TWO-TRANSISTOR, DIRECTLY CONNECTED OSCILLATOR
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Wiring Sequence:
o
1-29
o
2-30
o
3-48-138
o
5-101-44
o
26-45-76
o
27-85
o
28-124-137
o
46-102-86
o
47-43
o
75-119
o
121-122
Schematic