1. Device classification
1）Buzzer
Active buzzer: Built-in oscillation circuit, it will sound when powered on, but the tone is single.
Passive buzzer: It needs to be driven by an external pulse signal, the tone frequency can be controlled, and the cost is lower.
Type subdivision: Including piezoelectric (relying on piezoelectric ceramic vibration) and electromagnetic (driving the diaphragm through the electromagnetic coil).
2）Alarm and sirens
Especially used in high-intensity warning scenarios, such as ship alarm systems that must comply with specific military standards (such as MIL-DTL-0015303R).
2. Working principle and driving method
1）Sounding principle
Piezoelectric: The audio signal is generated by the multivibrator to drive the piezoelectric ceramic to vibrate.
Electromagnetic: The interaction between the electromagnetic coil and the magnet drives the diaphragm to sound.
2）Drive circuit
Commonly used NPN/PNP transistor or MOS tube drive, pay attention to the current limiting resistor and bleeder diode protection circuit.
When the microcontroller is driven, an external current amplifier chip (such as ULN2003) is required to provide sufficient driving capacity.
3. Application Scenarios
Consumer electronics: Prompt tone generation for computer motherboards, printers, electronic toys, and other devices.
Industrial and security: Fire alarm and equipment failure warning.
Automotive electronics: Reversing radar, safety system alarm.
Ship and military: Ship alarm devices that meet specific standards.
4. Selection and procurement
Parameter considerations: Operating voltage (1.5V-15V), sound pressure level, frequency range (1.5kHz-5kHz), etc.
Note: Some devices need to select the packaging type according to the scenario (such as a piezoelectric buzzer with a resonance box to enhance the volume).