Abstract: An electronic tester is disclosed that monitors the current capability of a storage battery without drawing heavy currents. It determines current capability from measurement of the battery's internal resistance is monitored in the conventional manner by drawing a small current load and observing the A.C. voltage generated at the battery terminals. The load circuit used here ensures that the current drawn is independent of battery resistance. The resistance signal is pocessed with a novel application of integrator circuitry to derive the battery's current capability.

Abstract: An electronic tester is disclosed that monitors the current capability of a storage battery without drawing heavy currents. It determines current capability from measurement of the battery's internal resistance. Internal resistance is monitored in the conventional manner by drawing a small current load and observing the A.C. voltage generated at the battery terminals. The load circuitry used here ensures that the current drawn is independent of battery resistance. The resistance signal is processed with a novel application of integrator circuitry to derive the battery's current capability.

Abstract: A circuit improvement and method leading to increased leak detection sensitivity is provided for gaseous leak detectors which utilize a hand held probe. The circuit modification provides a high pass filter and additional circuit gain which are switched together in or out of the detection circuit. When the modification is switched in circuit it is necessary to move the probe with a sweeping motion while searching for a gaseous leak.

Abstract: A quartz crystal gas pressure sensor senses a range of pressures within a gaseous environment, such as from 0.1 millibar to 1 bar. The sensor includes a quartz crystal connected to manifest a piezoelectric effect upon excitation by an alternating electric field and communicating with the gaseous environment, an oscillator circuit connected to the quartz crystal for generating the alternating electric field and including a feedback circuit for providing a signal for self-excitation at the resonant frequency of the crystal as well as indication of vibrational amplitude of the crystal as a function of gas pressure within the gaseous environment, and an indicator circuit connected to the feedback circuit for converting the electrical signal into an indication of the gas pressure sensed within the gaseous environment. A gas pressure measuring method is also described.

Abstract: Method and apparatus for the determination of the fuel flow condition of a fuel injector while the fuel injector is in its operative position in an engine are described. The device comprises a liquid reservoir, a measuring chamber for the liquid and a conduit to flow the liquid through the chamber to the injector under constant pressure, as well as electric circuitry to open and close the injector for at least one predetermined time interval. The chamber is refillable from the reservoir to a predetermined liquid level after each use. The liquid can be passed through the injector in short repeated bursts or in more prolonged flows. Comparison of the volume of liquid passing through the subject fuel injector in a given time period with the volume of a like liquid passed through a reference fuel injector in the same time period is indicative of the fuel flow condition of the subject fuel injector.

Abstract: A transducer coupling member for use with systems for detecting inhomogeneities in fluids flowing in a conduit. A first portion of the member is acoustically coupled to the conduit wall. An electromechanical transducer is mounted upon another portion. These two portions are partially acoustically coupled. The composite system forms a bandpass filter which eliminates frequencies and modes of oscillation which travel largely in the conduit, thus preventing the system from being rendered insensitive to inhomogeneities. The bandpass automatically adjusts to accommodate a variety of conduits.

Abstract: A detector comprises a pair of electromechanical transducers for disposition on a fluid-filled conduit in an acoustically coupled relationship, an adjustable gain driving amplifier responsive to the electrical output of one transducer for driving the other transducer, an automatic gain control circuit for automatically adjusting the gain of the driving amplifier maintaining the system on the margin of oscillation, and an indicating circuit for detecting modulation of the driving signal. Bubbles passing through the conduit increase the gain required to maintain the system on the margin of oscillation, and are detected as modulations of the driving signal. In a preferred embodiment, this bubble detector is utilized as a refrigerating system test instrument.

Abstract: This invention provides an apparatus for adjusting the scale and range of D'Arsonval pointer-type meters providing an uncluttered accurate readout particularly adapted for compact hand-held meters. Display wheels imprinted with numerals for a plurality of different scales are provided enabling the user to set, by manual rotation of a drive gear engaging a ring gear one of a plurality of desired ranges. The invention also provides for the simultaneous automatic selection or interconnection of circuit elements for driving the meter movement in accordance with the selected range.

Abstract: A detector comprises a pair of electromechanical transducers for disposition on a fluid-filled conduit in an acoustically coupled relationship, an adjustable gain driving amplifier responsive to the electrical output of one transducer for driving the other transducer, an automatic gain control circuit for automatically adjusting the gain of the driving amplifier maintaining the system on the margin of oscillation, and an indicating circuit for detecting modulation of the driving signal. Bubbles passing through the conduit increase the gain required to maintain the system on the margin of oscillation, and are detected as modulations of the driving signal. In a preferred embodiment, this bubble detector is utilized as a refrigerating system test instrument.

Abstract: The transducer functions as a capacitor to sense variations in inter-plate istances produced either by transducer displacement or by pressure. The capacitor plates include flexible rubber sheathing members having interior conductive surfaces spaced slightly from a conductive centrally-disposed metal plate. A pair of electrets are disposed one between each rubber surface and the central metal plate. Electrets are a battery replacement supplying a large electrostatic field. Opposite polarization of the electrets provides push-pull and directional capabilities. Like polarities, or the omission of one electrode, provide responsiveness both to pressure and to displacement. The central metal plate has sufficient mass to remain substantially stationary relative to the flexible movements of the rubber sheathing. Variations in the plate spacings produces variations in the capacitor output.