How does a doorbell work?
http://home.howstuffworks.com/home-improvement/repair/doorbell.htm
A doorbell works by using a combination of electrical and mechanical components. When someone presses the doorbell button, it completes an electrical circuit, which activates the bell or chime inside your home. Here is a step-by-step explanation of how a traditional wired doorbell works:
1. Button Press: When someone presses the doorbell button, a small metal piece inside the button touches a contact on the back, completing an electrical circuit.
2. Voltage Path: The completed circuit allows electricity to flow from the transformer, through the doorbell wiring, and into the doorbell button.
3. Transformer: The electrical current flows from the doorbell button to a transformer. The transformer's purpose is to convert the higher-voltage, low-current electricity from the utility line into a lower-voltage, higher-current electricity suitable for the doorbell system.
4. Chimes or Bells: From the transformer, the electrical current moves to the chimes or bells inside your home. These are electromechanical devices that produce sound when electricity passes through them.
5. Electromagnetism: Inside the chime or bell unit, there is an electromagnet. When electricity flows through this magnet, it creates a magnetic field that attracts a metal arm or striker.
6. Striking Mechanism: The metal arm or striker is typically connected to a bar, which strikes a metal plate or resonating chamber to create the sound.
7. Sound Generation: The striking mechanism hits the metal plate or resonating chamber, producing the familiar doorbell chime or bell sound.
It's important to note that the complexity and design of doorbells can vary; for example, wireless doorbells use radio frequencies instead of physical wiring to transmit electrical signals. Nonetheless, the basic principles of completing an electrical circuit and using electromagnetism to generate sound remain consistent.