Abstract: A method of gapping a ferrite core by coating the core with a stabilizing material, fracturing the core with a laser beam thereby creating one or more gaps in the core's magnetic field, optionally opening the fracture to obtain a desire inductance, and then sealing the core.

Abstract: A battery drain limitation circuit for use in engine powered vehicles and equipment which rely upon a battery to start the engine and also to operate accessories. When the engine is not running, the circuit disconnects the battery from all loads when battery charge, as measured by either one of two complementary means responsive to high and low drain rates, respectively, falls to a level below which the battery charge may not be sufficient to start the engine. High drain rates exaggerate battery voltage reduction below no load voltage levels, and are detected by a low cutoff voltage level after which the battery voltage recovers to reflect sufficient charge to start the engine. Battery dissipation from low drain rates is prevented by a long timing delay following detection of a high cutoff voltage level. The circuit is rendered inoperable if the engine is running, by means of a microphone which detects engine noise. The device is simple to install at the battery.

Abstract: A battery drain limitation circuit, for use in engine-powered vehicles and equipment that rely on a battery for starting the engine and for operating accessories, disconnects the battery from all loads when the battery voltage falls to a level below which the battery charge may be insufficient to start the engine. The circuit is rendered inoperable, when the engine is running, by means of a microphone that detects engine noise. The circuit includes a reset mechanism that reconnects the battery to all loads. The reset mechanism may be automatic or manually actuated. A timing circuit delays the disconnection for a period of time sufficient to start the engine. The drain limitation circuit employs a latching relay that, in its preferred embodiment, includes front and rear coils in tandem, axially separated by a collar with an internal detent. A front plunger and a rear plunger are disposed for axial movement within the coils and the collar.

Abstract: A linear variable differential transformer (LVDT), includes a hollow bobbin with first and second ends, a ferromagnetic core adapted for linear movement within the bobbin, a primary coil wound around the exterior of the bobbin, and first and second secondary coils wound around the primary coil. The first and second secondary coils are wound from starting points at the first and second bobbin ends, respectively. The seconardy coils are then wound continuously and simultaneously toward the opposite bobbin ends, so that the two secondary coils cross over each other at a cross-over point approximately halfway between the bobbin ends. The second secondary coil thus overlaps the first secondary coil between the cross-over point and the first bobbin end, and the first secondary coil overlaps the second secondary coil between the cross-over point and the second bobbin end. Each of the secondary coils has a sufficient continuous length to overlay substantially the entire length of the primary coil.

Abstract: An apparatus for winding two coils simultaneously on a bobbin, such as winding the two secondary coils of a linear variable differential transformer (LVDT), has a chuck or the like holding a bobbin. The chuck is rotated by a first motor. First and second wire guides move linearly in directions opposite to one another along the axis of rotation of the bobbin, and guide two strands of wire onto the rotating bobbin. The wire guides arrive simultaneously at the longitudinal center of the bobbin where the two strands of wire cross one another. The two wire guides are driven by two lead screws which rotate at identical speeds but in opposite directions to one another. The lead screws are driven by a second motor. The speeds of rotation of both motors are controlled by a computer, whereby the pitch pattern of the windings is determined by a computer program.