Instructions

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2.35 Mosquito repeller
Circuit 86: Mosquito repeller
Setup information
Install the two transistors, the four resistors and the three electrolytic capacitors as shown in 2.86 followed
by the eight jumper wires. Last but not least connect the Piezo element.
Check the placement on the board again and only then connect the battery.
Components required:
2 x 2N3904 transistors,
2 x 1 kΩ resistors,
2 x 100 kΩ resistors,
1 x 220 kΩ resistor,
2 x 220 nF ceramic capaci-
tors, 1 x 10 nF ceramic
capacitor, 1 x Piezo ele-
ment, 1 x breadboard,
1 x 9V battery with clip
connector
Fig. 2.86: Mosquito repeller
Experiment
If everything is wired correctly, you will not hear anything once the battery is connected. The sound waves
generated are in the frequency range of ultrasonic waves. Mosquitoes usually do not like this sound and
stay away. Now we hope you can leave your bedroom window open without being bothered by mosquitoes.
The Piezo element is not designed for such high frequency and therefore the volume is very low.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.86.