The access control switch, also known as the "door button" or the "door button" is an integral part of the access control device.

　　The principle of the door button, in fact, is the principle of a doorbell button, when pressed, the internal two contacts conduction, release the button bounce back, the contact disconnected.Therefore, some projects in which someone directly used the doorbell button to make a door button is also possible.But the doorbell button usually has a "bell" printed on it.