A piezoelectric microphone/buzzer is a sound component made by mounting a piezoelectric vibrating plate in a plastic box.

Piezoelectric microphones are sound components that can produce sound suitable for use as an input signal without the need for built-in oscillation circuitry.

The fundamental difference between an active buzzer and a passive buzzer is that the products have different requirements for the input signal; the ideal signal for an active buzzer to work is DC, which is usually labeled as VDC, VDD, etc. Because there is a simple oscillation circuit inside the buzzer, it can convert the constant DC current into a certain frequency pulse signal, and the alternating magnetic field from the surface real out, driving the molybdenum piece to vibrate and pronounce. However, some active buzzers can also work under specific AC signals, but the voltage and frequency of AC signals are very demanding, so this mode of operation is generally not used.