Abstract: A keyboard switch has a deformable membrane which, when deformed, enables electrical contact between a pair of contacts. A key stem is urged away from the deformable membrane by an elastic body. When the key stem is displaced sufficiently, the elastic body imparts a click feel. The key stem, when displaced a sufficient amount, deforms the deformable membrane to make the electrical contact.

Abstract: A balun transformer with a common mode coil is formed by parallel two-strand cable wound around a common core having through-holes through which the cable passes. The common mode coil can be connected either on the input side or the output side of the balun transformer. Because only one core is used to form both the balun transformer and the common mode coil, the outer dimensions of the transformer can be reached, along with manufacturing costs, to reduce the number of man-hours required to manufacture the transformer by this invention. This configuration also permits shorter connections between the balun transformer and the common mode coil.

Abstract: A multi-drop type bus line system having a plurality of terminals respectively connected to a common bus line, in which each terminal has a connector interconnecting with the other terminals and the connectors at the respective terminals are interconnected by means of a connection cable. Each connector is provided with a switch which is actuated each time the connection cable is coupled to the connector of the terminal, whereby when the connection cable is coupled to the connector, the switch releases an impedance matching resistor connected between predetermined terminal pins of the connector. Impedance matching is improved and standing waves are reduced.

Abstract: A key switch is disclosed wherein a key stem is slidably movable within a switch case. Upward movement of the key stem under spring bias causes electrical disconnection between a stationary contact and a movable leaf-spring terminal type contact both mounted within the switch case. The stationary contact is a wire engaging a sheet metal type leaf-spring terminal contact having notches to provide plural contact points therebetween.