Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 229

Circuit 206: Discrete Operational amplifier with Piezo element
Setup information
Install the three transistors, the four resistors and the two electrolytic capacitors as shown in Fig. 2.206 The
fifteen jumper wires come next. Last but not least connect the Piezo element. Check the placement on the
board again and only then connect the battery.
You can significantly increase the sensitivity of the Piezo element by using a sound plate or even a sound
box. Read more about it in Chap. 1.2.3
Experiment
If everything is wired correctly, you will have a simple audio amplifier with an operational amplifier. If you
connect an mp3 player to the input, you will hear the amplified sound of music coming from the Piezo ele-
ment.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.206.
Components required:
2 x 2N3904 transistors,
1 x 2N3906 transistor,
1 x 22 Ω resistor, 1 x 1 kΩ
resistor, 1 x 2.2 kΩ resistor,
1 x 10 kΩ resistor,
2 x 10 μF electrolytic
capacitors, 1 x Piezo ele-
ment, 1 x breadboard,
1 x 9V battery with clip
connector
Fig. 2.206: Discrete Operational
amplifier with Piezo element
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