The Truth About Doorbells
Whether it's a ding-dong, a buzzer, or a long-winded chime, whenever you drop by someone's home, you use a magnet every time you ring the doorbell.
Doorbells contain electromagnets, which are temporary magnets that activate only when electricity runs through them. To make an electromagnet, you need a ferromagnetic substance such as iron, wire, and a battery. Wrap the wire tightly around the piece of iron, attach the wire to the battery, and when the electrical current from the battery flows through the wire, the iron becomes highly magnetic. This strong magnetic force only lasts as long as the electric current flows through the wire, so it's an ideal way to create the temporary sound made by a doorbell.
Pushing a doorbell button causes the electrical circuit to close. The current runs through a transformer, which converts a standard household 120-volt current into the 6-16 volts needed for a doorbell to function. After going through the transformer, the current flows through the electromagnetic wire. Once enabled, the magnetic field moves a noisemaking apparatus to create the sound you hear.
Traditionally, doorbells make a few different noises. A buzzing doorbell sound occurs because the electromagnet draws on a contact arm that rests upon a metal contact peg. When you press the doorbell, the circuit closes, and the contact arm jumps between the metal contact and the electromagnet at a high rate of speed. As the contact arm moves, it creates the buzzing sound you hear.
A bell works similarly to a buzzer, except that the contact arm is also attached to a clapper, which is attached to a bell. The contact arm moves quickly and produces the brrring sound.
A chiming doorbell employs the use of a solenoid, a type of electromagnet where wire is coiled around a piston. The electromagnetic field moves the piston backward or forward. In the case of a chime, the doorbell apparatus will contain tone bars, and when the circuit is closed when the doorbell button is pressed, the piston will strike the tone bars to create the chiming sound. In a two-toned chime, the moves forward to hit one tone bar, then it moves backward rapidly to hit the second tone bar. This creates the "ding-dong" noise we're accustomed to hearing on many household doorbells. Add in a few more chime bars, and you can get elaborate chimes, such as the popular "Westminster Quarters" chime heard from many a clock tower.
In recent years, technology has changed this product. Electronic doorbells capable of playing long musical phrases and even voices have come on the market. They don?t contain any electromagnets; rather, when the button is pressed it registers an integrated circuit that triggers the song to go off. These doorbells can even be wireless, so when you press the button, it activates a transmitter that sends a radio signal to a doorbell radio receiver to activate the noise.
Although technology has attempted to infiltrate the world of doorbells and make them complicated products, a magnet is still the simplest way to see if someone is at home