What Is a Doorbell Circuit?


Quick Answer

A doorbell circuit is a low-voltage electrical circuit that causes a chime to ring when someone pushes the button, which is a single pole switch. The circuit receives power from a transformer that reduces 110-volt household current to the 10 to 20 volt power required for the doorbell.

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What Is a Doorbell Circuit?
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Full Answer

Most doorbells use chimes as a signaling device. The chime operates using an electromagnetic solenoid to activate a spring-loaded piston. When the circuit is completed, the electromagnet pulls the piston one direction, causing one end to strike a tone bar, creating the "ding." When the visitor removes his finger from the switch, the electromagnet releases the piston and the spring pushes it the opposite direction to strike the second tone bar, creating the "dong."

Electronic doorbells replace the solenoid and tone bars with an integrated circuit. When someone presses the switch, the doorbell circuit starts playback of a digitally recorded song. These doorbells have a much wider variety of options to notify the occupant of a visitor. Some electronic doorbells operate wirelessly; pressing the button activates a transmitter, and the transmitter sends a signal to a receiver to start the signaling device.

In order to provide power to the doorbell circuit, the transformer draws power constantly. Doorbell transformers typically draw 1 to 2 watts of electricity.

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