Abstract: A high current, high speed comparator switching circuit includes circuits to positively control turn on and turn off of switching transistors and counteract conduction overlap due to stored charge resulting from high current loads.

Abstract: A digital counter driven by a stable high frequency source generates a periodic signal synchronized to an external signal source. Gating circuitry responsive to particular digital counts, accumulated by the counter, defines precise quantized time intervals. The external signal is examined during these quantized time intervals for the occurrence of significant cyclic events such as zero crossing. A single occurrence of cyclic event is determined during a first time interval while successive multiple occurrences of the cyclic event are searched for during a second but smaller time interval. In each instance failure of the event searched for activates corrective circuitry to inhibit synchronous oscillation with the external signal source.

Abstract: An insertion-extraction tool to apply forces with mechanical advantage in the insertion and extraction of printed circuit boards into and out of an apparatus housing includes connecting means to secure the tool to the apparatus housing and engaging means to link with the printed circuit board being inserted and extracted.

Abstract: An alarm circuit to monitor a periodic signal source for an occurrence of a short-circuit condition detects the entry of the instantaneous periodic signal magnitude into a predefined window bounded by an upper and lower threshold. The duration of the entry is timed to determine if a short circuit has occurred.

Abstract: A three-phase rectifier utilizes three feedback controlled ferroresonant regulators to convert a three-phase signal into a regulated DC voltage. A monitoring circuit is included which responds to a signal loss at any input phase to actuate an alarm signal.

Abstract: A channel formed type unitary clamp is designed to fit over nearly abutting bar ends of cantilevered rack bars which are part of ladder racks used to support cables. The clamp includes locking tabs which are bent to lock the clamp onto the nearly abutting bars and are operative to stabilize the relative end positions of the nearly abutting bar ends.

Abstract: A converter designed to be powered by a constant current and variable voltage source such as a coaxial cable of variable length includes regulation circuitry to regulate the input voltage of the converter. In particular, the switching device of a single-ended converter is pulse width modulated to regulate the input impedance and hence the input voltage of the converter to permit its efficient operation at varying cable lengths.

Abstract: The inlet air temperature and the exhaust gas temperature of a gas turbine power plant are monitored and are utilized as a determining characteristic in a power output stabilization control circuit. The control circuit is designed to change its response upon the attainment of a particular inlet air temperature threshold to conform to differing high and low temperature operating characteristics of the gas turbine power plant.

Abstract: A digital feedback control for a switching regulator utilizes interrelated digital counting circuits to provide a combined proportional, integral and differential feedback. By generating a simultaneous interrelated feedback signal, the response time of the feedback control is improved and a significant reduction in circuit elements is permitted.

Abstract: A switching regulator includes a digital feedback control circuit to regulate the output voltage. The frequency output of a voltage controlled oscillator responsive to the output voltage is periodically counted. The accumulating count is continuously compared with a reference count. The elapsed time for this count to accumulate to a value equaling the reference count determines the duty cycle of periodic conduction through the switching device of the switching regulator.

Abstract: A single-ended converter circuit operating in a transformer coupled mode is disclosed having multiple outputs. A current limiting circuit is included on the primary side of the power transformer to limit the total aggregate current output of the converter. Secondary current limiting circuitry is included in selected ones of the multiple outputs to individually limit current outputs of the converter. A similar current limiting arrangement is disclosed for application to double-ended type converter circuits.

Abstract: A single-ended self-oscillating DC-to-DC converter is disclosed including base drive compensation circuitry. Compensation circuitry is active during saturation intervals of the power transistor to control its forced current gain at some fixed value irrespective of the magnitude of a saturated current flowing through the transistor.

Abstract: A static electromagnetic frequency changer utilizes linear inductances and capacitances and a saturable reactance to generate subharmonic frequencies. The magnetic components of the circuit are designed to be combined on a single magnetic structure. The frequency changer is rendered relatively insensitive to slight changes in the frequency and amplitude of the driving signal through the inclusion of a feedback winding.

Abstract: An uninterruptible power supply derives regulated power from either a primary power source or a reserve power source. A power flow control unit derives the output power as needed from either one or both power sources. Its operating characteristics are selected so that complicated transfer and disconnect circuitry is eliminated.

Abstract: A ferroresonant voltage regulator utilizes control of the voltage peak of a signal waveform as a voltage regulation technique. The peak of the voltage waveform is adjusted in response to a feedback control. The regulated output voltage is derived from a peak voltage detector.

Abstract: A transfer switch to selectively transfer an electrical load from one high voltage source to another includes a shaft connected to a handle. Spaced close to opposite ends of the shaft are two circular slotted cams. Cam followers connected to opposite ends of a follower bar are inserted in the cam slot. The follower bars connected to the cam followers are connected to vacuum interrupter contacts (mechanical vacuum relays). The transfer switch is constructed so that as the cam is rotated the contacts connecting one high voltage source to the electrical load are closed and as the cam is continued to be rotated the contactors of the previously connected high voltage supply are subsequently released.

Abstract: Alternately triggered SCRs are driven by alternately operating pulse circuits sharing a common timing circuit. A cross inhibit circuit prevents misfires by suppressing spurious trigger signals which may be coupled from one pulse circuit to another.

Abstract: An uninterruptable power supply supplies a regulated output by utilizing a ferroresonant transformer. Two independent inputs are connected to the transformer; one input is connected to a commercial AC line signal source, the other input is connected to a battery energized static inverter circuit. The AC line source normally supplies the output power. A phase control system monitors the phase of the regulated output signal and constrains the static inverter to run in phase with the output. The phase and magnitude of the AC line signal are monitored. If the magnitude of the AC line drops significantly, the static inverter is constrained to operate in phase with the AC line signal wherein the inverter and AC line both share to contribute power to the output load. If the AC line signal fails, the static inverter operates independently and supplies all of the output power to the load.

Abstract: A single-ended converter circuit combines a magnetic energy storage medium with an energy discharge path to simplify transformer design, improve transformer operating characteristics, and reduce induced electromagnetic interference. The concept is extended to self-oscillating, single-ended converters and a double-ended type is achieved by combining two single-ended converters with a single power transformer structure.

Abstract: In a typical self-oscillating, single-ended converter that is pulse width modulated to regulate the output signal, duty cycle changes to stabilize the output signal cause the switching frequency of the converter to vary.The switching frequency of the single-ended converter disclosed herein is stabilized by controlling the on and off durations of the switching device in an inverse proportional relationship to each other. The relation is controlled by adjusting the charging threshold of a timer circuit controlling the conducting interval of the switching devices in response to a voltage regulation error signal which controls the nonconducting interval thus limiting the total period of the switching device to a fixed interval.