Abstract: A system is described for use in controlling the position of window closures in poultry houses without the use of significant electric power in response to sensed air conditions within the house. The system includes pulleys releasibly loaded on a cable connected to a curtain which have respective weights that may lift and lower the curtain when the pulleys are released.

Abstract: A piezoelectric pump includes a hollow cylindrical piezoelectric crystal (12) with end bells (22) and (24) on either end defining a pump chamber (14). A resilient diaphram (32) with an offset orifice (34) provides afferent valving action and a resilient diaphram (44) with an offset orifice (46) provides efferent valving action. Connecting leads (52) and (54) allow a voltage source (56) to be periodically connected to the crystal (12) by a switch (62). A resistor (64) is disposed between one pole of the switch (62) and the connecting lead (54) to allow decay of the charge on the crystal (12). By sensing the voltage on the lead (52) during relaxation of the crystal 12, the internal load can be monitored to provide an indication of the pumping operation. Automatic monitoring is provided by a computer (104).

Abstract: An air trimmer capacitor has a tubular housing having an interior wall formed with angularly spaced flats that are interconnected with conically arcuate wall sections. A coil spring is confined within the housing in contact with the flats. A rotor is threadably received in the coil spring that supports an electrode in adjustably spaced relation with a stationary electrode.

Abstract: An electronic device such as a multi-turn trimming capacitor and potentiometer has two conductive elements and means for rotating one element with respect to the other. The rotating means includes a drive member coupled with one conductive element such that an angular displacement of the drive member with respect to the other conductive element imparts less angular displacement to the one conductive element with respect to the other conductive element. Rotation of the one element is achieved while sealing both elements from ambience.

Abstract: A method and apparatus of pumping a fluid by means of a piezoelectric pump is provided. All moving parts, including the valves and impeller, are piezoelectrically motivated. The preferred embodiment includes a piezoelectric ceramic tube having conductive bands adhered to the outer surface. The conductive bands and an inner surface electrode define tube regions which serve as valve and reservoir pump regions.

Abstract: An apparatus for pumping a fluid by means of a piezoelectric pump is provided. All moving parts, including the valves and core, are piezoelectrically motivated. The preferred embodiment includes a piezoelectric ceramic tube having conductive bands adhered to the outer surface. The conductive bands and an inner surface electrode define tube regions which serve as valve and reservoir pump regions. A sensing circuit senses the voltage on the outer electrodes of the innermost of the piezoelectric regions to detect the presence of faulty pumping operation. The sensing circuit utilizes the piezoelectric effect that results from internal loading of the core.