Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 98

Circuit 75: RC high pass 160 Hz
Setup information
Install the transistor and the electrolytic capacitor as shown in Fig. 2.75. Last but not least, connect the
Piezo element. Check the placement on the board again.
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
We will use electrical filter circuits, among other things, to suppress the noise. The basic circuit that serves
this purpose is a RC or LC filter consisting of a resistor/inductor and a capacitor. Depending on the wiring,
this creates a low pass or a high pass. In our case, we are using an RC high pass filter. The cut-off frequency,
that allows signals to pass, is 160 kHz. If you connect an mp3 player to the input, you will hear that the bass
is cut off.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.75.
100
Components required:
1 x 1 kΩ resistor,
1 x 1 μF electrolytic
capacitor, 1 x Piezo ele-
ment, 1 x breadboard
Fig. 2.75: RC high pass 160 Hz