Abstract: A two dimensional digitizing system comprises two systems at right angles to each other, comprising two conducting grid structures each having three terminals A, B, and C, with the grid conductors running parallel to the X axis in one system and the Y axis in the other, and a cursor coil. When the cursor coil is excited with an alternating current, voltages e.sub.ab, e.sub.bc and e.sub.ca are induced between the terminal pairs AB, BC and CA respectively, whose amplitudes are functions of the position of the cursor coil relative to a cartesian co-ordinate system defined by said X and Y axes.The voltages e.sub.ab, e.sub.bc and e.sub.ca from each system are phase shifted and summed to provide two single signals e.sub.x and e.sub.y whose phase shift from a reference signal derived from the cursor coil excitation is a linear function of cursor coil displacement along the X and Y axis respectively.The phase shifting is accomplished by a passive network connected to the three grid winding terminals.

Abstract: A two dimensional digitizing system comprising two systems at right angles, each system having at least two conducting grid systems. Each grid system is comprised of a number of windings with a pitch distance D and an equal number of windings with a pitch distance D+.DELTA.d, where .DELTA.d is a small increment in distance. These windings produce a number of voltages whose amplitude varies cyclically as an AC excited cursor coil is moved in a direction at right angles to the conductors in a plane parallel to the plane of the conductors. Active or passive networks are provided for converting the grid voltages into signals whose phase with reference to the cursor coil excitation current varies linearly with cursor position. These signals are cyclic in nature going through a phase displacement of 360 degrees when the cursor moves through distance D in the case of one grid winding and a distance D+.DELTA.d in the case of the other grid winding.

Abstract: An engine diagnostic apparatus includes a first transducer positioned in the oil filler neck of the engine for translating the crankcase pressure waveform into a corresponding electrical waveform having a frequency component proportional to engine speed. A second transducer is positioned to translate an exhaust pressure waveform emitted by the engine to a corresponding electrical waveform having a frequency component representative of an engine fault at a frequency proportional to engine speed. The two frequency components are compared to provide diagnostic information.

Abstract: An automobile alternator test apparatus tests for the presence of a failed diode by detecting a frequency component (a subharmonic component) in the alternator output ripple voltage produced by the failed diode. The subharmonic frequency component is detected by a tracking filter that is slaved to the subharmonic frequency of the ripple frequency voltage produced by the failed diode. The output signal of the slaved filter indicates the presence of the failed diode.

Abstract: The cylinder of an internal combustion engine having a fault is identified by using a non-contacting transducer to generate a reference engine-cycle electrical signal having a phase determined by a reference one of the cylinders of the engine, and by using a non-contacting transducer to generate a fault engine-cycle electrical signal having a phase determined by the one of the cylinders having a fault. The phase difference between the fault electrical signal and the reference electrical signal is translated to a number identifying the cylinder having the fault.

Abstract: A conduit arrangement for measuring unburned combustibles in the exhaust eam issuing from an engine. A restriction is provided in the exhaust duct to form a superatmospheric pressure zone upstream from the restriction and a subatmospheric pressure zone downstream from the restriction. A minor fraction of the exhaust gas is bypassed around the restriction through a conduit system communicating with the two above-mentioned zones. A sampling chamber containing a combustibles sensor is located in the conduit system. An auxiliary conduit communicates the interior of the sampling chamber with the ambient atmosphere so that cooling air is drawn into the chamber to dilute the sampled gas. The dilution air lowers the temperature of the gas-air mixture, thereby cooling the sensor against heat degradation by the otherwise undiluted gas. The dilution air also contributes oxygen to the gas stream, thereby enhancing catalytic oxidation processes on which certain sensors depend for response to combustibles (CO and CH).