Tapping a piezo buzzer gives an interesting waveform, with a voltage spike followed by an envelope, and then a negative rebound voltage. It’s something [Igor Brichkov] is using, to make a simple ...

It runs on mains power and uses a 100dB piezo buzzer for ear-splitting effectiveness to alert [Adam] whenever the freezer is at 32°F/0°C or above. If the Arduino loses sight of the DHT22 ...

Arduino is a great way for today’s novices to start to ... Digital (pwm) pin D3 drives the piezo-buzzer through a PNP transistor, and the analog pin A0 takes care of the 10K trimpot. Analog pin A4 is ...

Although piezoelectric buzzers generate sound waves when you apply an ac voltage, you can use them in the opposite way: You obtain the maximum ac peak voltage that the piezoelectric buzzer generates ...