Abstract: A fuse for responding to external temperatures to interrupt an electrical circuit, for example for interrupting a telephone battery feed in response to the temperature of a battery feed resistor, comprises a substrate carrying a pair of electrodes defining a gap between them. A fuse link, for example a gold strip, extends across the gap to interconnect the electrodes electrically. A film of solder overlies the fuse link and overlaps at least partly at least one of the electrodes. The fuse link is soluble in the molten solder so when the temperature of the solder paste exceeds its melting point, it melts, dissolves the fuse link, and retreats from the gap to sever the electrical connection between the electrodes.The fuse and a resistor whose temperature is to be detected, may be provided on a single substrate.

Abstract: A pushbutton switch assembly, for a keyboard, comprises a plurality of switch units each having at least a pair of superposed switch contacts, one of which is movable by an actuator to make or break contact. Each actuator is a hingedly mounted cantilever having a pushbutton at its free end. When the pushbutton is depressed an intermediate part of the cantilever actuates the movable switch contact. The cantilever is dimensioned so that the operating force needed at the pushbutton is only a fraction of that required to operate the switch contact directly. Also the pushbutton travel is correspondingly longer. Accordingly the assembly may use a relatively stiff, small travel type of switch unit, for example a snap-action spring plate or flexible membrane, yet provide at the pushbutton the "soft" action and long travel preferred by so many users.