Abstract: A method and apparatus for charging a bulk energy storage capacitor, such as used for actuating solenoids in downhole tools. An electrical generator, which may be a mud-powered, provides a rectified voltage proportional to its rotational speed. The rectified voltage is fed to a single-ended primary-inductor converter, which in turn charges the bulk capacitor 16 when the voltage across the bulk capacitor falls between predetermined upper and lower set points. Upon discharging the bulk capacitor, such as from actuation of solenoid valves for creating mud pressure pulses, control logic also causes the converter to cease charging the bulk capacitor 16 to enhance circuit efficiency and performance. A battery may also be provided to charge the bulk capacitor via a current limiter, and a disconnect circuit prevents the battery from charging the bulk capacitor when the generator is charging the bulk capacitor via the converter.

Abstract: A measurement-while-drilling system includes a lower toroid, wherein the lower toroid has a lower toroid winding and is adapted to engage a mud motor shaft and is further adapted to receive a signal from one or more sensors and an upper toroid, wherein the upper toroid has a upper toroid winding; and a magnet disposed along the mud motor shaft within the lower toroid. The lower toroid and the upper toroid are disposed so that a signal from the lower toroid is induced in the upper toroid. The lower toroid winding is non-uniform so that the signal induced in the upper toroid is indicative of a rotation rate of the mud motor shaft.

Abstract: A measurement-while-drilling system includes a lower toroid, wherein the lower toroid has a lower toroid winding and is adapted to engage a mud motor shaft and is further adapted to receive a signal from one or more sensors and an upper toroid, wherein the upper toroid has a upper toroid winding; and a magnet disposed along the mud motor shaft within the lower toroid. The lower toroid and the upper toroid are disposed so that a signal from the lower toroid is induced in the upper toroid. The lower toroid winding is non-uniform so that the signal induced in the upper toroid is indicative of a rotation rate of the mud motor shaft.

Abstract: A downhole measurement assembly comprising a metal casing housing a plurality of tool sections, one of which includes a detector sensitive to a magnetic field, and a DC power supply for said tool sections, the power supply and the tool sections being electrically connected to the casing, characterised in that the power supply is connected to at least one tool section via a switching circuit and a conductor arrangement, the switching circuit comprising a capacitor, a plurality of switches and control means operative alternately to charge the capacitor from the DC supply and discharge the capacitor through said at least one tool section using the conductor arrangement so as to inhibit the generation of an electromagnetic field in the conductor arrangement between the capacitor and the said at least one tool.

Abstract: A downhole measurement assembly comprising a metal casing housing a plurality of tool sections, one of which includes a detector sensitive to a magnetic field, and a DC power supply for said tool sections, the power supply and the tool sections being electrically connected to the casing, characterised in that the power supply is connected to at least one tool section via a switching circuit and a conductor arrangement, the switching circuit comprising a capacitor, a plurality of switches and control means operative alternately to charge the capacitor from the DC supply and discharge the capacitor through said at least one tool section using the conductor arrangement so as to inhibit the generation of an electromagnetic field in the conductor arrangement between the capacitor and the said at least one tool.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may include receiving a received signal, such as a substantially sinusoidal signal, provided by a driven element, such as a magnetostrictive device, coupled to a non-atmospheric medium and an amplifier having substantially zero quiescent current in the absence of an input signal, wherein the amplifier is to receive a pulse modulated wave comprising an original signal substantially similar to the received signal.