Abstract: A universal phase-controlled reversible power converter having one transformer with multiple windings (i) couples a fixed d.c. voltage to an associated transformer winding through a fixed port having switches controlled for switching by fixed-phase signals, and (ii) couples any number of voltages having any waveform(s) whatsoever each to an associated transformer winding each through an associated variable port that has a filter with an inductor and controllable switches. Variable-phase switching control signals control the variable ports to produce any desired three-state demodulated waveform. A three-state demodulated waveform is filtered to present (i) a corresponding counter emf of any desired waveform to an input source or power, or (ii) any desired output waveform to a sink of power. Controllably producing the counter emf as a picture-of-the-line-input-voltage makes the load factor of the power converter, and all its loads, unity.

Abstract: A universal phase-controlled reversible power converter having one transformer with multiple windings couples a d.c. voltage to an associated transformer winding through a fixed port having controllable switches; and further simultaneously couples any number of a.c., d.c., combination a.c. and d.c. or stochastic voltages, each to an associated transformer winding and each through an associated variable port having a filter with an inductor and controllable switches. All couplings, transpiring in any number of relatively independent ports, are to an equal duty cycle substantially constant amplitude square wave within the transformer's windings. Any number of relatively independent open-loop transfer functions, or closed feedback control loops, may be simultaneously active (i) to control switching in variable ports so as to continuously couple power regardless of its waveform or distortion, or regardless of variations in waveform or distortion even so far as changes between a.c. and d.c.

Abstract: A regulated, low-voltage DC power source which draws energy from a standard AC outlet and uses a bank of lead-acid batteries for intermediate power storage.The power source features a multi-level charge-voltage controller which is automatically adjusted in function of the net current flowing in or out of the batteries. The charge-voltage control is accomplished by switching the charging current rectifiers on or off only at the zero-axis crossing in order to minimize voltage spikes, and only at every other crossing in order to minimize DC components in the secondary of the transformer. Charge current, load current and net battery current are separately metered in order to provide maximum efficiency and safety in the operation of the power source. A low-voltage-drop series regulator is relied upon to provide a 5 volt regulated output to the load from a 6 volt unregulated battery voltage source.

Abstract: A DC power supply comprising a sealed lead-acid battery, a charging regulator, a discharge pass element, an output power switch for disconnected the power supply from the computer and four light-emitting diode indicators which display the condition and trend of the battery charge state. The power supply may be permanently attached to an Apple IIc brand computer without marring the computer's plastic housing by means of tabs on upper and lower projections of the power supply housing which interlock with slots on the upper and lower surfaces of the computer's housing. The power supply also features an electronic "sleep" switch which not only prevents battery drain when the power output switch is turned off, but also prevents deep discharge of the battery and possible damage to the powered equipment when battery voltage drops below a preset value while the output switch is turned on and adequate voltage from the power line is unavailable.

Abstract: Each ultrasonic transducer in a plurality provides a particular signal having characteristics related to the heart rate of an associated fetus. Each particular signal is processed in an associated labor room monitor and modulated on a different carrier frequency for transmission on power lines in the hospital. At a remote location, a nurses station power unit is modular with nurses station monitors. The line signals are individually demodulated in an associated one of the nurses station monitors to provide an indication of heart rate. Alternatively, the transducer assemblies can be coupled to delivery room monitors to provide an indication of heart rate.The transducer assemblies are uniquely shielded to inhibit interference of spurious low frequency signals with the particular signals. The particular signals are partially detected in the transducer assemblies so that the assemblies can be used with both the labor room and delivery room monitors.