Abstract: A telephone apparatus includes a phone jack arrangement (299) providing an interface to land lines from the central office and other telephone apparatuses. Phone jack arrangement (299) comprises a phone jack (306) having inner conductors (420, 422) coupled to outer conductors (406, 408) of a phone jack (304), and outer conductors (424, 426) coupled to inner conductors (402, 404) of phone jack (304). Condition detectors (232, 234) detect whether phone lines of phone line circuitry (270) are connected to land lines, and microprocessor (212) may operate the telephone apparatus or configure base station user interface (126) accordingly. A two-line operating mode may select one of the phone lines for operating use upon detection of a predetermined condition from condition detectors (232, 234) or ring detectors (246, 248). Thus, a multi-line telephone apparatus operates flexibly according to different phone line connections.

Abstract: A method of operating a multi-line telephone apparatus includes, when a phone line switch (140) is actuated, taking a phone line off-hook when the line is on-hook and bringing the phone line on-hook when the line is off-hook. When the phone line is off-hook and a hold switch (164) is actuated, a hold condition is placed on the phone line when the line is not on hold and removed when the line is on hold. When a phone call is established on a first phone line and a conference switch (160) is actuated, a second phone line is brought off-hook and a conference call connection is established. A common conventional method of making a conference call, which includes actuations of hold switch (164) and phone line switches (140, 142), is retained.

Abstract: An electronic battery equalization circuit that equalizes the voltages of a plurality of series connected batteries in a battery pack. The current waveform is in the shape of a ramp for providing zero current switching. The ramp converter power circuit has at least one semiconductor device and a transformer coupled to the equalizing voltage supply source. The transformer has a primary winding circuit and at least one secondary winding circuit. In one embodiment, each secondary winding circuit is connected to a different pair of batteries. The equalizing current is provided to the lowest voltage batteries in one half of the battery pack during one half of the charging cycle. The equalizing current is then provided to the lowest voltage batteries in the other half of the battery pack during the other half of the charging cycle. In another embodiment, each secondary winding circuit is connected to a different single battery.

Abstract: A full bridge DC to DC converter which provides zero voltage switching (ZVS) for one leg of the bridge and zero current switching (ZCS) for the other leg of the bridge is described. ZVS is achieved with parallel capacitors, while ZCS is achieved by using the reverse breakdown characteristics of the various diode and switching devices. This technique provides a significant reduction in the switching losses of the switching devices, which allows for higher power and frequency combinations.

Abstract: A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator.

Abstract: A microprocessor based A.C. motor control circuit which can be used for both open and closed loop control includes a pair of RAMs for storing separate groups of synchronized digital waveforms for driving an A.C. motor. The microprocessor is used to calculate the group of digital waveforms required to maintain a controlled motor parameter at a desired value. One RAM has an output connected to supply the group of digital waveforms stored therein to a motor driver, while the second RAM is connected to receive a new group of digital waveforms which have just been calculated by the microprocessor. Once the new group of waveforms have been loaded into the second RAM, the microprocessor generates control signals to disconnect the output of the first RAM from the motor driver, and to connect the output of the second RAM to supply the newly calculated digital waveforms to the motor driver. The first RAM is then connected to receive the next group of digital waveforms to be calculated by the microprocessor.