A simple buzzer is an electromechanical device that converts electrical energy into sound energy. It works based on the principle of electromagnetic induction. The basic components of a simple buzzer include:
Electromagnet: A coil of wire wound around a metal core. When current flows through the coil, it generates a magnetic field around the core.
Armature: A small piece of magnetic material, typically made of iron or steel, that is attracted to the electromagnet when a current flows through it.
Contact points: These are metal strips that make and break the electrical connection between the electromagnet and the power source.
When the buzzer is connected to an electrical circuit and the power is applied, the current flows through the coil, creating a magnetic field around the metal core. This magnetic field attracts the armature towards the core, causing it to move and make contact with the contact points. When the contact is made, the current flows through the coil and keeps the magnetic field active.
However, as the armature makes contact, it also completes another part of the circuit, which includes the coil. This creates a self-interrupting mechanism. As the current flows through the coil, the magnetic field becomes stronger, pulling the armature more firmly towards the core, and this increases the pressure on the contact points. Eventually, the pressure becomes strong enough to break the contact between the armature and the contact points. As a result, the circuit is broken, and the current stops flowing through the coil.
With the current interrupted, the magnetic field around the core collapses. This causes the armature to move away from the core due to its own spring-like behavior or a built-in spring. Once the armature moves away, the contact points close again, completing the circuit. The process then repeats, creating a rapid on-off cycle for the current, causing the armature to vibrate or oscillate between the core and the contact points.
The rapid oscillation of the armature creates sound waves in the surrounding air, producing the buzzing sound that you hear from the buzzer.
This on-off cycle continues as long as power is supplied to the buzzer. The buzzing sound will be produced at a frequency determined by the rate of on-off cycles per second, and this frequency determines the pitch of the sound. Different buzzers can be designed to produce different pitches based on the materials used and the mechanical properties of the armature and spring.