doorbell

A doorbell is a signaling device installed at an entry to announce a visitor's presence. It typically consists of a push button at the doorway, a chime unit inside the building, and a power source. When the button is pressed, an electrical circuit is closed and the chime sounds. Modern systems may use mechanical, electric, wireless, or smart technology.

Mechanical and electric doorbells use a transformer to supply low-voltage power to a chime. Pressing the button energizes the circuit and drives a sound-producing mechanism. Wireless doorbells rely on battery-powered transmitters and receivers that communicate via radio signals, bypassing the need for wiring. Smart doorbells combine doorbell signaling with cameras, two-way audio, motion detection, and mobile apps for remote monitoring.

Chimes vary in tone, duration, and number of notes. Some systems provide single-note ding-dong; others offer multiple chimes or programmable sounds. Many doorbells can distinguish front and rear entrances by using separate chimes or zones.

Power and installation considerations include typical wired doorbells using around 16V AC supplied by a transformer, and requiring proper wiring to the doorframe and chime. Wireless models run on batteries and require occasional replacement. Smart doorbells require a Wi-Fi or network connection and are installed near the door with a camera and microphone.

Historically, doorbells evolved from simple mechanical signaling devices to electrically powered systems in the 19th and 20th centuries, with modern wireless and smart variants becoming common in recent decades.

Security and privacy considerations apply especially to smart doorbells, which may capture video and transmit data. Users should secure networks, manage access, and review privacy settings.