How Does a Doorbell Really Work?Jason Warren
Did you ever wonder how your doorbell works? In the typical electric type, an electrical circuit is completed using a switch (your button outside), an electromagnet and a battery or transformer. The electromagnet is activated by the electric current (supplied by battery or transformer) which causes: a buzzer to go off, a bell to ring or a magnetic clapper (or hammer) to strike chime bars, creating sound.
- Electrical circuits:
- A broken, interrupted electrical circuit is “off” – with no electricity running through it. That’s because the circle/circuit that the electricity runs around is no longer complete.
- A complete or closed circuit is “on” – it allows electricity to flow from a transformer or battery around the entire closed circuit.
- Integrated circuit – Wireless doorbells use this to transmit sound via radio waves to a receiver/speaker.
- Electromagnet: This is a magnet wrapped in a wire coil, which acts as a motor to operate your doorbell. A magnetic field is produced when electricity passes through the wrapped coil, activating the magnet. The coiled wire amplifies the magnetic field, making it stronger. Think of an electromagnet as a “temporary” magnet that is only “on” (or magnetized) when electrical current runs through the wire/coil on a closed circuit.
- Solenoid: An electromagnet where the coiled wire surrounds a piston with a magnet at its center. The magnet in the piston is moved back and forth by the electromagnetic field when a circuit is opened/closed.
- Switch: Your doorbell’s button acts as an electrical switch that completes an electrical circuit, allowing power (electrical energy) to flow.
- Transformer: Takes your household electrical current and turns it from 120v down to 10v (low voltage), which is all that is needed to power your chime.
What Happens when You Press a Doorbell?
The electromagnet is activated when you push the doorbell button at someone’s front or back door.
- The button acts as a switch that completes the electrical circuit – allowing electricity to flow from the transformer or battery. (Completing a circuit is also called closing it, which means that it is no longer broken and electricity can flow through it.)
- The building or home’s electrical current passes through the transformer, turning 120 V household current into 10 V current needed to run the doorbell. (In wireless models, electricity may come from a battery.)
- The electrical current then passes through the wire around the magnet, which generates an electromagnetic field.
- The attraction of the magnetic field drives a sound-making device, usually a metal bell with a tiny hammer or clapper.
How the Doorbell Rings: What’s Happening Inside?
This simple chime setup consists of a bell with a spring-loaded clapper next to it. An electromagnet controls the clapper, which is ready to strike if activated.
- This simple chime is switched on/activated when the puch button is pressed, bringing electrical contacts together. That completes a circuit and activates the electromagnet.
- The magnetic action pulls the clapper toward the electromagnet.
- When released, the clapper springs forward and strikes the bell. In this case, it’s not just the front door button that controls the whole electrical circuit. The clapper is also part of the circuit.
- As the clapper strikes the bell, it simultaneously breaks the circuit, cutting off power to the magnet.
- The spring snaps/pulls the clapper back again to its starting place. In returning to the starting position, the clapper completes the circuit again-which re-activates the magnet to strike the bell again. This continues as long as you keep the button pressed. This is called a self-interrupting circuit.
- A self-interrupting circuit explained: The doorbell is “on repeat” until you release the button. When you DO release the button by the front or back door, it is pushed back out by its own spring, interrupting the circuit that you first created when you pressed it…however, if you keep your finger on the bell…
- When you continuously keep the button pushed, without releasing it – the bell keeps on ringing! That’s because the clapper is on a “self-interrupting” circuit that just keeps on cycling – breaking and completing the circuit over and over, until you decide to release the button!
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One end of the electromagnet’s wire is directly connected to the electrical circuit. The other end of the wire connects to a metal contact, next to a moving arm (kind of like a clapper). This contact arm is made of thin and light metal, with one end resting on a contact point and the other end connected to the electrical circuit.
- When the doorbell button is pressed, the circuit closes, letting electricity flow and generating the electromagnetic field. The field attracts a metal bar that pulls the contact arm away from the metal contact. This breaks the circuit and de-energizes the electromagnet.
- The contact arm snaps back into its starting place. This completes the circuit and lets electrical current flow through the circuit.
- The magnetic field is generated and repeats the prior step above: attracting the metal bar, pulling the contact arm away from the metal contact. This breaks the circuit and de-energizes the electromagnet once again.
- The “buzzing” buzzer sound comes from the contact arm quickly flapping back and forth between the electromagnet and the contact point, several times per second.
Inside this bell are 2 vertical bars of different types/thicknesses of metal, which make different sounds when struck. The vertical metal bars act as “bells” to make the familiar ding and dong sounds. Separating the 2 vertical bars are batteries, a spring and a small electromagnetic clapper or hammer – to do the striking. The magnetic hammer is a cylinder inside a horizontal plastic tube. This “cylinder-in-tube” setup is just like a piston or small battering ram – and is called a solenoid. To operate:
- Press the door chime button (which acts as the switch) completing the circuit.
- The electromagnet activates – it pulls the piston or metal inner cylinder (clapper or hammer) to the right, which compresses a spring.
- The sudden movement of the metal cylinder (the clapper/piston) and the collapsing spring allow the clapper to strike the right-hand bell (vertical metal bar) making the ding sound.
- As the metal cylinder (clapper) hits that right-hand metal bar, it breaks the circuit, switching the electromagnet off – so the spring then re-expands suddenly.
- This sharply snaps the metal cylinder (hammer/piston) back the other way, striking the left-hand chime (vertical bar) and making the dong sound.
- The vertical metal chime bars vibrate as the sound dies out – for that little extra drama!
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Multiple chimes for apartments or office buildings: Electric doorbells for multi-unit dwellings or offices will complete one of many circuits – to ring the bell in the selected apartment number only, as you press the button. In older buildings, you may find a round or cool rotary style. These were patented back in the 1930s. To operate this type of chime, you first turn the dial to select the apartment/office you’re visiting. Then you press the button in the center to get the circuit going and ring the bell.
Wireless or electronic styles: Wireless electronic doorbells use a special kind of circuit – called an integrated circuit. How do these work?
- Pressing the push button causes a recorded digital sound to be transmitted. The button is battery-powered and the system is wireless.
- The doorbell button/switch acts as a transmitter, sending a radio signal for a distance of up to about 300 ft. to the receiver/speaker in your home.
- The signal reaches your indoor battery-powered ringer/receiver or speaker – which emits a sound. This indoor speaker plugs into a wall outlet – or you can carry a portable transmitter with you to the back yard.
Most wireless chimes offer several different radio channels, so you can use a different one than your neighbor to avoid mix-ups! There are several quality advanced wireless doorbells for the hearing impaired that offer visual signals in addition to audible features.
Wireless Style Advantages:
- No wiring: Wireless doorbells require no wiring. Hard-wired styles need to be hooked up to the electrical system in your home and may require an electrician. The coordinating button uses a small battery that lasts a long time.
- Amplified reach: These modern wireless bells make it easier to hear, even if you are far away in the back yard, for example. Many people with large homes choose wireless doorbells – you can carry the battery-powered ringer (also called a receiver or speaker) with you when you are far from the front door of your house. You can also install (plug in) extra speakers throughout the house. Here are some excellent options to extend the range of your doorbell.
When you need help selecting a new stylethat’s perfect for your home or business needs, call on the experts at 1800Doorbell.com. We can also help you with troubleshooting your old/existing chime, and offer guidance on installation of new ones. Call us today at 800-366-7235 or contact us online at 1800Doorbell.com!