Abstract: A converter circuit that derives its bias power from voltage supplied by a tertiary winding including a tertiary winding voltage level responsive circuit with a hysteretic characteristic to selectively enable and disable the drive circuitry controlling the converter's power switching transistor. Should the bias voltage drop due to an output fault, the converter is operated at a subfrequency of its normal operating frequency in order to prevent operating the power switching transistor in its active region during high current conduction.

Abstract: A transformer includes a preformed winding with each turn having a channel cross section. The individual units are joined to form the desired multiturn winding. Another winding is inserted within the channel cross section of the multiturn winding. In one embodiment, the channels of the two turns are joined to form a closed passageway. In another embodiment, they are nested one within each other to form a concurrent passageway.

Abstract: A self-oscillating power converter utilizes a MOSFET power transistor switch with its output electrode coupled to a tuned network that operatively limits the voltage waveform across the power switch to periodic unipolar pulses. The transistor switch may be operated at a high radio frequency so that its drain to gate interelectrode capacitance is sufficient to comprise the sole oscillatory sustaining feedback path of the converter. A reactive network which is inductive at the operating frequency couples the gate to source electrodes of the transistor switch and includes a variable capacitance as a means of adjusting the overall reactance, and hence the converter's switching frequency in order to provide voltage regulation. A resonant rectifier includes a tuned circuit to shape the voltage waveform across the rectifying diodes as a time inverse of the power switch waveform.

Abstract: A combination latch/switch mechanism is operative to lock a circuit board into a support housing and enable and disable selected circuits during the insertion process. A lever of the mechanism includes a notch to engage the support housing and a contact arrangement engaging and disengaging circuit paths as the circuit board is inserted into the housing.

Abstract: Harmonic currents of the line frequency on the input line of a power converter are significantly reduced by actively controlling the input current to have substantially the same waveform and be in phase with the input AC sinusoidal voltage. Specific peak current control techniques are utilized to constrain current in an input inductor to be in phase with and approximate in waveform the input voltage sinusoidal waveform by operating a switch at a much higher frequency than that of the input AC voltage source; with the peak current control using the input AC voltage as a controlling reference voltage waveform.

Abstract: A turn off circuit for an inductivity loaded power switching transistor utilizes a transistor current path in the base circuit and two series connected diode junctions in the emitter circuit to reverse bias the base-emitter junction of the power switching transistor without the need for an active reverse bias voltage source.

Abstract: An off-line switcher flyback-type power converter circuit is designed having energy and operative control circuits operating off a tertiary winding of the power transformer. A delayed current shutdown circuit permits starting in the face of high demand current loads whereby the load is supplied with bursts of current as start up is cyclic and delayed shutdown is also cyclic in this situation.

Abstract: A low profile magnetic structure comprising E and I type core shapes is dimensioned with the passage length through the core window being very long compared with a cross sectional dimension of the windows. In a transformer design, windings passing through the window are designed to be coaxial with one winding being a shell for the other winding.

Abstract: A current converter circuit that supplies send and return currents to a balanced transmission line includes current sensing circuitry that responds to a current unbalance or a differential current, independently of longitudinal currents in the balanced line. A reference voltage and two inputs to a comparator monitor the voltage drop across a voltage divider connecting the send and return leads of the transmission line. The voltage divider has a grounded center tap so that longitudinal currents flow to ground and provide equal and opposite polarity voltages across the divider, which cancel each other. Unbalanced currents provide a corresponding differential voltage input to the comparator, whose control voltage output is utilized to initiate corrective action in a current control circuit.

Abstract: A terminal removal tool for removing terminals from a printed circuit board, includes a pliers arrangement with special jaws to engage the terminal. Each jaw includes a housing to enclose an end of the terminal and a wedge which is positioned to engage an underside of the terminal when the pliers are closed. The end of the housing rides on the surface of the circuit board to properly position the wedges and when the pliers are closed the action of the wedges breaks the friction fit of the pins holding the terminal to the circuit board.

Abstract: A microcomputer surveillance system is operative to monitor the output signal of a power supply to determine if an alarm limit has been reached and to center the alarm limits around an operating point of the power supply. Sensed output signals are converted to signal frequencies and transmitted optically to counters which accumulate counts indicative of the output signal. A microcomputer controller uses these counts to set alarm limits and determine if an alarm limit has been exceeded.

Abstract: A series type ferroresonant regulator is modified by adding a second ferro-capacitor in parallel with the primary winding of the saturating transformer. This arrangement allows the transformer to operate at a much cooler temperature than is possible with a conventional series ferroresonant regulator of the same power rating.

Abstract: A stored program energy control system operates with the control of a telephone communications system to improve its energy efficiency by removing power from station sets and their associated visual indicators when they are inactive. Inactive station sets are identified by establishing minimal intervals of nonuse to define the inactive status. The energy control system responds to events like incoming calls and switchhook activity to restore power to the station set. Since energy is applied to a station set only when precisely needed, the overall energy drain of the system is greatly reduced.

Abstract: A snap-in bus bar is mechanically affixed to a printed circuit board to increase mechanical stiffness of the board and electrically connected to the printed circuit paths to provide a high current capacity conducting path. The bus bar includes a support member to provide insulation between conducting members attached thereto.

Abstract: A signal coupling arrangement including a dual detector opto-isolator arrangement operative to transfer a sensed DC signal from an input to an output of an amplifying circuit with an isolated electrical system there between incorporates amplifiers having a specific gain set by unique calibration means and to initially preset the coupling circuitry amplification gains to assure a consistent DC current transfer and DC contrast ratio in coupling DC signals from the input to the output.

Abstract: A voltage controlled flyback converter used as a battery charging circuit avoids the power dissipation of the more conventional series-type regulator-type charging circuits but cannot be readily utilized because of the high gain in the feedback loop due to the battery voltage, which causes instabilities therein when it is operated in a continuous current mode.These instabilities are avoided in a flyback converter used for battery charging by using current control techniques to control current on the primary side of the converter during high-rate battery charging. During low-rate charging, normal voltage feedback from an output current sensing resistor is used as long as the converter operates in a discontinuous mode.

Abstract: A digital phase and frequency comparator circuit establishes phase and frequency windows to determine if two AC signals are in phase and of substantially the same frequency. A phase difference between the two signals is determined by exclusively ORing the two signals and timing the duration of a signal state to determine if the phase difference exceeds a threshold. The two AC signals are also ANDed and counted to determine the frequency agreement.

Abstract: A power converter circuit, which is voltage-regulated and current-limited by a peak current control circuit, significantly reduces the current tailout effect by decreasing the frequency of operation of the converter during low voltage output current-limited operation by increasing the nonconduction interval of the power switch while maintaining a fixed conduction interval.The peak current control circuit periodically initiates current conduction in the power switch in response to a clock pulse, and terminates conduction when a peak current level is attained. The peak current control includes circuitry to compare decaying current in the filter circuit during nonconducting intervals with a preset current tailout threshold level. The periodic triggering of the power switch into conduction is inhibited until current has decayed to this current tailout threshold level.

Abstract: A transconductance amplifier capable of operating from a single supply voltage includes a differential input stage energized by a current mirror current source. Small voltages are sensed across the emitter junctions of the two transistors of the differential input stage. A feedback arrangement is included to stabilize the gain of the transconductance amplifier.

Abstract: A full-wave rectifier is implemented in CMOS integrated circuit chip technology. Two transistors are used in a bridge arrangement with two diodes to implement the rectifier while avoiding parasitic transistor action which previously provided an unwanted current path through the chip substrate to defeat full-wave rectification.