Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 174

Experiment
If everything is wired correctly, you will hear a clear tone with a sinusoidal waveform coming from your
Piezo element once the battery is connected. This is a pure tone without any harmonics unlike the complex
tone, which would be composed of several pure tones. This is also the reason why a pure tone sounds arti-
ficial and sterile. In our case, frequency is about 100 Hz. You can use this test signal to check audio circuits.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.150.
Circuit 151: Simple tone generator 100 Hz
Setup information
Install the transistor, the five resistors and the three ceramic capacitors and the electrolytic capacitor as
shown in Fig. 2.151. The thirteen 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 hear a clear tone with a sinusoidal waveform coming from your
Piezo element once the battery is connected. This is a pure tone without any harmonics unlike the complex
176
Components required:
1 x 2N3904 transistor,
1 x 47 Ω resistor,
1 x 2.2 kΩ resistor,
2 x 4.7 kΩ resistors,
1 x 220 kΩ resistor,
3 x 100 nF ceramic
capacitors, 1 x 10 μF
electrolytic capaci-
tor, 1 x Piezo element,
1 x breadboard, 1 x 9V
battery with clip con-
nector
Fig. 2.151: Simple tone
generator 100 Hz