Abstract: A current sensing assembly includes a conductor, first and second magnetic sensors disposed proximate to opposite sides of the conductor and being structured to output first and second voltage signals, a current direction detector circuit structured to detect a direction of a current flowing through the conductor, a switching circuit having first and second outputs and being structured to switch between a first condition where the first voltage signal is output to the first output and the second voltage signal is output to the second output and a second condition where the first voltage signal is output to the second output and the second voltage signal is output to the first output based on the switching signal, and an output circuit including a differential amplifier structured to amplify a voltage difference between the first and second voltage signals and to output the amplified voltage difference.

Abstract: A current sensing assembly includes a conductor, first and second magnetic sensors disposed proximate to opposite sides of the conductor and being structured to output first and second voltage signals, a current direction detector circuit structured to detect a direction of a current flowing through the conductor, a switching circuit having first and second outputs and being structured to switch between a first condition where the first voltage signal is output to the first output and the second voltage signal is output to the second output and a second condition where the first voltage signal is output to the second output and the second voltage signal is output to the first output based on the switching signal, and an output circuit including a differential amplifier structured to amplify a voltage difference between the first and second voltage signals and to output the amplified voltage difference.

Abstract: Electrical equipment is safeguarded from damage due to faults by a circuit that provides several levels of protection. A semiconductor switch and a current sensor are placed in series with the electrical equipment. When the current to the equipment exceeds a first threshold for a predefined period of time, the semiconductor switch is rendered non-conductive until the circuit is specifically reset. When the current to the equipment exceeds a greater second threshold, a pulsed signal alternately places the semiconductor switch in conductive and non-conductive states so that the average current applied to the equipment is within an acceptable level. Should the current exceed an even greater third threshold, the semiconductor switch is immediately rendered non-conductive until the circuit is manually reset.

Abstract: An electrical current sensing apparatus includes a magnetic flux sensor which may be disposed adjacent to or within an opening in a conductor. The magnetic flux sensor may be disposed adjacent to a corner of the opening around which magnetic flux resulting from a current conducted through the conductor tends to concentrate. The magnetic flux sensor includes a Hall effect device having a flux sensitive surface. In one embodiment, the conductor has a tubular cylindrical side wall with an opening in which the magnetic flux sensor is disposed. In another embodiment, the conductor has a rectangular configuration with an opening in which the magnetic flux sensor is disposed. In another embodiment, the magnetic flux sensor is mounted on the surface of the conductor adjacent to the opening.

Abstract: An electrical sensing apparatus includes a conductor having longitudinally extending sections with parallel central axes and a connector section which extends between the longitudinally extending sections. The connector section has a central axis which extends parallel to the central axes of the longitudinally extending sections. A magnetic flux sensor is disposed adjacent to the connector section to detect variations in current conducted through the conductor. The magnetic flux sensor may be at least partially disposed in a slot in the connector section and have a flux sensitive side surface which extends perpendicular to a central axis of the connector section. The magnetic flux sensor may include an electrically insulating material which is at least partially enclosed by the connector section and a Hall effect device which is supported by the electrically insulating material. The electrically insulating material may be disposed in engagement with the connector section.

Abstract: A power tool has a variable speed control circuit that comprises a user switch, a motor and a silicon controlled rectifier (SCR) connected in series between a pair of power supply terminals. A manually variable resistor is connected between a first electrode of the SCR and a circuit node. A capacitor is coupled between the circuit node and a second SCR electrode. A bleed-off resistor is connected between second electrode of the SCR and the circuit node to provide a path for discharging the capacitor when the user switch is open. A zener diode couples the circuit node to the SCR gate electrode. The circuit configuration ensures that the capacitor charges from substantially the same voltage level at the start of each half-cycle during which the SCR is to be turned on.