The Magnetic Field Driven "Sound Maker"

As the name suggests, an electromagnetic buzzer operates on the principle of electromagnetic induction. Its core components include an electromagnetic coil, a magnet, a vibrating diaphragm, and a housing. When an audio-frequency current passes through the coil, it generates a magnetic field that varies with the signal. This field interacts with the built-in magnet, driving the diaphragm to vibrate periodically and produce sound.
A key characteristic is that it can achieve decent sound pressure even at low operating voltages, but it typically draws a relatively high current. In terms of drive methods, it comes in two types: self-drive (active) types, which have a built-in oscillator circuit and produce a fixed frequency sound when powered, and external-drive (passive) types, which require an external square wave signal for tone control. They are widely used in computers, printers, alarms, and other devices.