Class A End-Level - Maker Factory ELECTRONICS EXPERIMENTS BOX Manual

2.92 Class A end-level

Circuit 197: Class A amplifier with Piezo element
Setup information
Install the transistor, the four resistors and the two electrolytic capacitors as shown in Fig. 2.197 followed
by the four jumper wires. 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
Even if everything is wired correctly, nothing will happen at first. But if you connect an mp3 player you will
hear the music blasting from the Piezo element. This little circuit is very useful in various DIY projects.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.197.
222
Components required:
1 x 2N3904 transistor,
1 x 220 Ω resistor,
2 x 22 kΩ resistors,
1 x 47 kΩ resistor,
2 x 10 μF electrolytic
capacitors, 1 x Piezo ele-
ment, 1 x breadboard,
1 x battery, 9V battery with
clip connector
Fig. 2.197: Class A amplifier with
Piezo element