Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 99

Circuit 76: High pass from on 1.6 kHz
Setup information
Install the transistor and the electrolytic capacitor as shown in Fig. 2.76. 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, the sound is bizarrely
brassy.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.76.
Components required:
1 x 1 kΩ resistor, 1 x 100 nF
ceramic capacitor, 1 x Piezo
element, 1 x breadboard
Fig. 2.76: RC high pass from on
1.6 kHz
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