Low Pass - Maker Factory ELECTRONICS EXPERIMENTS BOX Manual

2.30 Low pass

Circuit 72: RC low pass 1.5 kHz
Setup information
Install the transistor and the electrolytic capacitor as shown in Fig. 2.72. 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 low pass filter. The cutoff frequency,
up to which signals can pass, is 1.5 kHz. If you connect an mp3 player to the input, you will hear how dull
the playback sounds at such a bandwidth.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.72.
Components required:
1 x 100 Ω resistor,
1 x 1 μF electrolytic capaci-
tor, 1 x Piezo element,
1 x breadboard
Fig. 2.72: RC low pass 1.5 kHz
97