Elenco 130-in-1 Electronics Playground - Manual (Page 114)

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Now you are going to produce a loud sound by
combining an operational amplifier with two
transistors. After you finish the wiring, set the switch
to position A to turn on the power. You hear a loud
sound from the speaker when you press the key.
A capacitor-resistor oscillator is the signal source for
this sound. The operational amplifier acts as an
inverting amplifier, and transistors Q2 and Q3 cause
the speaker to create the sound. This circuit is called
a single ended push-pull circuit (SEPP). You have
learned about push-pull circuits. Single ended
signifies that the circuit has only one output. Most
amplifiers have a second output that is connected to
the negative (–) side of the battery.
Notes:
EXPERIMENT #95: OP AMP POWER AMPLIFIER
Wiring Sequence:
1-29
2-30
3-90-67-47-44
5-94-48-119-124
73-81-86-87-32-113-45-131
33-63-43
35-46-70
76-92-36-134
91-88-104-40
75-100-111-41
74-114-42
68-80-89
69-93
79-138
82-84
83-102-103
85-99-101
112-137
121-135
122-132
Schematic