Abstract: In one embodiment, a battery charger is configured to provide a normal charge current during a first time period and to supply a maintenance current after the first time period expires.

Abstract: A power controller (10, 70) forms a pass-through zone of output voltages. When the output voltage is between an upper limit and lower limit of the pass-through zone, the power controller (10, 70) continuously connects the input voltage to the output to form the output voltage. When the output voltage is above the upper limit or below the lower limit of the pass-through zone, the power controller (10, 70) switches the output transistors (42, 58) to form the output voltage.

Abstract: A circuit and method provides a regulated dc—dc power conversion. Active switches, saturable core inductors, and a diode are used in a quasi-synchronous circuit. During a part of the cycle (the “blocking interval”) free-wheeling current is routed through free-wheeling diode while a saturable core inductor is in a high-impedance, blocking state. During other parts of the cycle an ac inverter voltage is rectified by active switching devices, preferably field effect transistors (FETs). The circuit provides regulated, low voltage outputs with low conversion losses.

Abstract: A circuit and method provides a regulated dc-dc power conversion. Active switches, saturable core inductors, and a diode are used in a quasi-synchronous circuit. During a part of the cycle (the “blocking interval”) free-wheeling current is routed through free-wheeling diode while a saturable core inductor is in a high-impedance, blocking state. During other parts of the cycle an ac inverter voltage is rectified by active switching devices, preferably field effect transistors (FETs). The circuit provides regulated, low voltage outputs with low conversion losses.

Abstract: An output voltage regulation system allows independent output regulation of multi-output dc-dc switched-mode power converters. The channel resistance of MOSFET synchronous output rectifiers are controlled to obtain the voltage drop required to keep the respective output between predetermined limits concurrent with wide excursions in output load. A typical circuit has a transformer with an input winding coupled to a dc source. A transformer has at least a first and second output winding. A switched-mode regulator means samples a portion of the first output voltage and provides at least a first pulse-width modulated drive voltage having a first state and a second state to a first input semiconductor switch control terminal. The drive voltage first state turns the input semiconductor switch on and the drive voltage second state turns the input semiconductor switch off.

Abstract: An output voltage regulation system allows independent output regulation of multi-output dc-dc switched-mode power converters. The channel resistance of MOSFET synchronous output rectifiers are controlled to obtain the voltage drop required to keep the respective output between predetermined limits concurrent with wide excursions in output load. A typical circuit has a transformer with an input winding coupled to a dc source. A transformer has at least a first and second output winding. A switched-mode regulator means samples a portion of the first output voltage and provides at least a first pulse-width modulated drive voltage having a first state and a second state to a first input semiconductor switch control terminal. The drive voltage first state turns the input semiconductor switch on and the drive voltage second state turns the input semiconductor switch off.

Abstract: A multi-output, multi-directional power converter has an input bi-directional switch and at least a first output bi-directional switch, a coupled inductor having an input winding and at least one output winding. The coupled inductor input winding is connected in series with the input voltage source and an input bi-directional switch. Each coupled inductor output winding is connected in series with a corresponding output voltage source such as a capacitor and its respective output bi-directional switch. A clock circuit provides a first and second control signal. Each control signal has a first and second state. The second control signal has a state that is the complement of the first control signal. The first control signal is connected to the input bi-directional switch control terminal and the second control signal is connected to each respective output bi-directional switch control terminal.

Abstract: A circuit and a computer program for enabling the monitoring of a plurality of switch settings at remote sites by central telephone exchange equipment through regular telephone lines is described. To compensate for slow drift variations in line impedance, the impedance of each line is continually calculated from the measurements, and any small change is used to update a line impedance correction factor, while any large instantaneous change is used to update the data counter. Telephone exchange battery variations which may be large and instantaneous, are compensated for by measuring the battery voltage immediately prior to measuring the line impedances, and correcting the line impedance readings with a battery voltage correction factor. Other types of temporary signal interference which are frequently present in telephone switching equipment are identified and rejected by applying consistency criteria to multiple readings which have been corrected by the aforementioned method.

Abstract: A portable transmitter intended to be used to broadcast a signal in response to an external actuation can be constructed so as to include a board such as a so-called printed circuit board carrying a metal coil serving as an antenna. This coil surrounds a central region of the board carrying the operative components of the transmitter other than the antenna and carrying as much excess metal as can be conveniently located generally within the antenna. With this structure, the components and any metal located as described serve as capacitance adjacent to the antenna. As a consequence of the structure the effect of any capacitance adjacent to the exterior of the transmitter is minimized so as to improve antenna performance. When the antenna forms a part of an oscillator circuit in the transmitter so as to determine the oscillator frequency this structure minimizes the effect of any capacitance external to the transmitter affecting the oscillator frequency.