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A crash bar (also known as a panic exit device, panic bar, or bump bar) [1] [2] is a type of door opening mechanism which allows users to open a door by pushing a bar. While originally conceived as a way to prevent crowd crushing in an emergency, crash bars are now used as the primary door opening mechanism in many commercial buildings.
This type of switch is also known as a Normally Open (NO) Switch. (Examples: doorbell, computer case power switch, calculator buttons, individual keys on a keyboard) A 'push to break' switch does the opposite, i.e. when the button is not pressed, electricity can flow, but when it is pressed the circuit is broken.
In electronics, a latch-up is a type of short circuit which can occur in an integrated circuit (IC). More specifically, it is the inadvertent creation of a low-impedance path between the power supply rails of a MOSFET circuit, triggering a parasitic structure which disrupts proper functioning of the part, possibly even leading to its destruction due to overcurrent.
Modern manual door closer Eclipse door spring and separate checking mechanism. A door closer is a mechanical device that regulates the speed and action of a door’s swing. [1] Manual closers store the force used to open the door in some type of spring and reuse it to close the door. Automatic types use electricity to regulate door swing behavior.
A gated SR latch circuit diagram constructed from AND gates (on left) and NOR gates (on right) A gated SR latch can be made by adding a second level of NAND gates to an inverted SR latch. The extra NAND gates further invert the inputs so a SR latch becomes a gated SR latch (a SR latch would transform into a gated SR latch with inverted enable).
A push-button (also spelled pushbutton) or simply button is a simple switch mechanism to control some aspect of a machine or a process. Buttons are typically made out of hard material, usually plastic or metal. [1] The surface is usually flat or shaped to accommodate the human finger or hand, so as to be easily depressed or pushed.
The first modern direct-pull electromagnetic lock was designed by Sumner "Irving" Saphirstein in 1969 [6] [7] [8] for initial installation on doors at the Montreal Forum. [9] Fire concerns by local authorities in locking the doors at the Forum prompted management to find a locking solution that would be safe during a fire incident.
The first known example of a tumbler lock was found in the ruins of the Palace of Khorsabad built by king Sargon II (721–705 BC.) in Iraq. [1] Basic principles of the pin tumbler lock may date as far back as 2000 BC in Egypt; the lock consisted of a wooden post affixed to the door and a horizontal bolt that slid into the post.