Abstract: A solid-state switch is connected in series with a load between the poles of an electrical power supply. It includes an isolated gate bipolar transistor with an emitter connected to the internal ground and connected to the load and a collector connected to one pole of the supply and driving an input of a subtractor the other input of which is connected to receive a set point voltage. The output of the subtractor drives a feedback system connected to the gate of the transistor. The voltage at the gate is then representative of the current in the switch and is applied to interrupter means which sends a turn-off signal if the gate voltage exceeds a (triggering) threshold value. The turn-off signal sends to a switching circuit a turn-off voltage which produces a turn-off bias and disables the feedback circuit.

Abstract: A piece of electrical apparatus, such as a junction box, having a body of insulating material has at least one sleeve to receive and position the screw of a connecting terminal and, projecting into the sleeve, at least one resiliently deformable protuberance, to retain the screw and prevent it from dropping out, the protuberance being formed by means of a thinned down zone of the wall of the sleeve. Further retaining means may be provided comprising one or more ribs projecting into the sleeve and extending longitudinally of the sleeve for a part of the length of the sleeve at the inner end of the sleeve.

Abstract: An acoustic warning device of the type comprising a striker member which is also the movable core member of a control solenoid. A radially polarized permanent magnet is disposed at one end of the solenoid, e.g. opposite a gong therefor, and a spring defines with the permanent magnet a rest position of the core/striker member. The end of the core/striker member proximate to the permanent magnet is limited in its outward displacements within the axial extent of the permanent magnet means. The flux through the solenoid is carried mainly by the core member. The alternating polarization of the core/striker member ends is alternately attracted and repelled by the magnetic flux of the permanent magnet which is the equivalent of an imaginary axially polarized magnet in the passage through the solenoid.

Abstract: In a tool for tightening clamps, of the kind comprising a flexible strip and an apertured head, having a passage in which the end of the flexible strip can be engaged after the strip has been passed around a bunch of articles to be clamped together and through the apertured head, the tool being used to cut-off that portion of the flexible strip of the clamp which projects beyond the apertured head following tightening to a greater or lesser degree of the clamp around the articles, the improvement comprising a displacement member, a trigger and coupling means including a swinging link provided between the displacement member and the trigger and including a sudden release mechanism comprising a cam having a cam surface with two separate stable zones separated from one another by an unstable zone and a cam-follower maintained in contact with the cam surface of the cam, the cam and the cam-follower being relatively movable to swing said cutting lever from a rest position into a working position, one of the cam an