Abstract: A current supply has a first voltage summing circuit with two inputs, one of which receives a signal that indicates a desired current level to be produced. A current source produces a current level at an output in response to a control signal received from the first voltage summing circuit. The current source output is coupled to a center tap of the primary winding of a transformer that has a capacitor connected across the end terminals of its primary winding. Separate transistors connect ends of the primary winding to a common node and a resistor couples the node to circuit ground. A sensor produces a voltage e.sub.i that is proportional to a magnitude of the current flowing through said capacitor. A second voltage summing circuit produces an output voltage e.sub.t equivalent to the sum of voltage e.sub.i and the voltage across the resistor and the output voltage e.sub.t is applied to the other input of said first voltage summing circuit.

Abstract: A X-ray emissive vacuum tube is fully enclosed in an electrically conductive casing with electrical terminals through which bias potentials are applied to the tube. Occasionally an arc discharge occurs between electrodes within the tube generating a high frequency signal which ordinarily resonates with the conventional casings. However a resistive coating is applied to the inner surface of the case. That coating has a resistivity sufficient to lower the Q of the case to a value at which significant ringing does not result from the discharge.

Abstract: An information retrieval system for extracting information from a pair of substantially coherent electromagnetic waves represented by phase differences therebetween each of which is incident on a photodetector, and having a demodulator which receives the photodetector output signal and which also receives a reference signal. The reference signal is obtained through use of a phase shift detector which receives the photodetector signal to determine certain phase shifts occurring therein and provides this information to a reference signal supply to adjust the phase of its output signal which then serves as the reference signal for the demodulator.

Abstract: An assembly for an X-ray imaging apparatus has a vacuum tube with an envelope containing an anode, a cathode and a filament. The vacuum tube is enclosed in an electrically conductive casing along with a high voltage supply for the tube. Electrical current is supplied to components within the casing by one or more transformers that extend through openings in the casing. Each transformer has an annular core that is sealed to the casing by magnetically non-conductive material. Another magnetically non-conductive seal extends across the central opening in the core. Thus each transformer is mounted in a manner that hermetically seals the aperture through which it extends. Each transformer has a one winding magnetically coupled to the core outside the casing, and another winding magnetically coupled to the core inside the casing and connected to an internal component of the assembly.

Abstract: Apparatus for measuring the velocity of, for example, an aircraft includes two optical units spaced a predetermined distance apart along an axis, there being a plurality of pairs of associated radiation detectors, with each pair of detectors having one detector in each unit, the planes of lines of sight of each pair of detectors extending parallel to each other, with these planes of different pairs of detectors being inclined relative to each other, in a measurement period, comparing means of the apparatus determining the delay between the forward and aft detectors of at least one pair of detectors receiving radiation from the same part of the same portion of the plane of a radiation source, such as the terrain, and from this determination the velocity being represented, the comparing means possibly comprising a known form of correlator, possibly provided by a digital computer, the computer possibly also providing axis transformation means within the apparatus.

Abstract: An electronic door control system is disclosed having a d.c. motor rotatable in one direction for opening a door and in the opposite direction for closing the door. One or more semiconductor devices (preferably SCR's) supply d.c. power to the motor from an a.c. power source when rendered conductive. A polarity selecting circuit controls the polarity of d.c. power supplied to the motor and thus its rotational direction. A sensor (e.g. floor mat) senses body pressure near the door to enable conduction of the semiconductor device and provide a first d.c. power polarity for a predetermined period to open the door. A circuit reverses the polarity after the door is opened, thereby closing the door. A speed control circuit responsive to counterelectromotive force developed by the motor effectively controllably varies the conductivity of the semiconductor device in a sense tending normally to cause motor rotation, and thereby door movement, at a predetermined speed.