Abstract: A DC to DC switching regulator includes a first pulse width modulator (PWM) (26) and two switching transistors (48) and (50) that are coupled to a transformer (18) to generate an output signal that has pulse widths variable in response to the PWM (26). The output of the transformer (18) is rectified to provide a regulated DC output. A second PWM (78) is provided to convert the amplitude of the regulated DC output to a stream of pulses that are input to an isolation transformer (112) by a push-pull arrangement of transistors (118) and (120). The pulse width of the pulses input to the isolation transformer (112) is variable as a function of the level of the regulated DC and the amplitude thereof is a constant referenced to the internal reference of the PWM (78). The output of the isolation transformer (112) is rectified and filtered to provide an error signal that varies in response to the pulse width of the output pulses from the PWM (78).

Abstract: Medical suction apparatus is disclosed including in combination a rigid outer canister having a cover and a disposable semi-rigid inner liner or container. Mounting assembly means coacts with the canister and cover to seal the container within the canister. The container is a cup-like member which maintains its cup-like shape before, during and after use within the canister. A simple and efficient snap-fit mounting assembly includes an annular sealing support lid on the upper peripheral lip of the container. The lid is snap-fit mounted to the rim of the canister to support the container therefrom. This mounting also establishes a gap between the container and canister, as well as sealing such gap. The cover is snap-fit mounted to the annular lid to compress the container lip and an upper section of the container sidewall between the cover and the lid. This mounting seals the interior of the container. The lid may be released from the canister without breaking the seal between the cover and container.

Abstract: A pump (10) is disclosed for use in pumping a fluid (14) from a borehole (12) to the surface. The pump includes a first and second pumping string (20, 22) extending into the borehole and a return string (26) extending from the borehole. First and second pistons (82, 94) are slidably mounted at the ends of the first and second puming strings within the borehole, respectively for reciprocation between extended and retracted positions. First and second pumping cylinders (56, 64) are secured in fixed relation to the first and second pumping strings (20, 22) so that the first and second pistons (82, 94) are slidable therein. The pistons and pumping cylinders define first and second pumping chambers (92, 104). Each of the first and second pistons includes a gear rack (88, 100) having teeth meshing with the teeth on a stroke return gear (106).