Abstract: A boost power converter for powering a load with an AC power source. The boost power converter has an energy storage device, a resonant circuit, a resonator switch circuit, a boost inductor circuit with a boost inductor, and a boost switch circuit. The resonator switch circuit alternately connects the resonant circuit to different sides of the energy storage device, where power from the energy storage device is transferred by the resonant circuit to the load. The boost switch circuit selectively connects the boost inductor to the resonator switch circuit, such that the boost inductor is charged in one of two different directions depending on the phase of the AC power source. The boost power converter is well-suited for ballast applications that drive a fluorescent lamp.

Abstract: The power delivery of an energy source (10) is enhanced by a dual function circuit. The circuit utilizes a storage capacitor (32) to store a voltage higher than the source voltage by transferring charge from the energy source to the storage capacitor between current pulses (16), than transferring charge from the storage capacitor to the load during current pulses. This is achieved by the novel combination of a boost converter (40) operating in conjunction with a buck converter (45).

Abstract: A boost-converter with low losses having a series connection of an energy storing main inductor and a main diode connected between a first input terminal for a first voltage and a first output terminal for a second, higher dc-voltage. The centre point between the components connected in series is, via a controllable switching element, connected to a common second input and output terminal. A control circuit for the switching element is provided to monitor the voltage of the first output terminal of the converter and to control the on and off operation of the switching element.

Abstract: In accordance with the present invention a power supply for providing an ac/dc output to a load is disclosed. The power supply includes a first source of dc power and an inverter that provides an ac output to the load. A second source of dc power is provided and selectably connects the first and second sources of dc power in series with the load when the output current reverses. In one embodiment the power sources are connected in series with every output current reversal. The first source of dc power is controllable and the magnitude of the dc current is responsive to a current reference signal. A control circuit provides the current reference signal, wherein the current reference signal is pulsed immediately prior to the ac output reversing polarity. The first source of dc power source preferably includes a buck converter that is switched at a variable frequency, depending upon the desired output current.

Abstract: A buck-boost power converter for powering a load from an AC power source having a full resonant circuit for applying an alternating voltage to the load. A choke is connected to the full resonant circuit and a switching device switches the choke in quasi-resonant manner to an input power rectifier to produce high power factor power conversion.

Abstract: An uninterruptible power supply for providing continuous power from a power source line to a load is provided. In particular, the uninterruptible power supply may either operate in an "Off-Line" mode or one of two "On-Line" modes. The uninterruptible power supply operates in the "Off-Line" mode when the power source line voltage is above a first threshold value. The uninterruptible power supply routes power from the power source line to the load in the "Off-Line" mode. The uninterruptible power supply operates in a first "On-Line" mode when the power source line voltage drops below a first threshold value but exceeds a second threshold voltage, or the frequency of the power source line exceeds a predetermined range. The uninterruptible power supply boosts the power source line voltage in the first "On-Line" mode of operation and applies the boosted signal to the load.

Abstract: A booster type DC-DC conversion circuit and a voltage reduction type DC-DC conversion circuit are connected in series with a battery. When battery voltage is high, the booster type DC-DC conversion circuit does not operate, and the voltage reduction type DC-DC conversion circuit outputs a constant voltage lower than the battery voltage. When the battery voltage drops, the booster type DC-DC conversion circuit operates, and converts the battery voltage to a constant voltage higher than the operation voltage of the voltage reduction type DC-DC conversion circuit. The voltage reduction type DC-DC conversion circuit outputs a constant voltage. The power supply apparatus can continuously output a constant voltage from when the battery voltage is high until it becomes low, and can efficiently utilize the battery capacity.

Abstract: An uninterruptible power system has a transformer with a primary connected to input terminals, a secondary connected to output terminals, a static switch connected between the input terminals and the primary, and an auxiliary primary connected to an inverter which is supplied by a battery to provide output voltage to the output terminals when a main AC power system connected to the input terminals has failed. The primary has multiple taps at different voltage levels and a buck-boost winding. The taps of the transformer are switched and the buck-boost winding is controlled to provide either buck, boost, or pass-by to allow control of the output voltage from the transformer to within a few percent of a desired voltage level despite large changes in the input voltage.

Abstract: A switching regulator composed of a push-pull converter with a buck or boost regulator connected upstream. The output inductance of the regulator is split into two separate inductances each of which is fed to one leg of the push-pull circuit. The push-pull converter is expanded to a resonance converter by means of resonance capacitors. This switching regulator has a high efficiency and is particularly suitable for use in satellite power supplies.

Abstract: A synchronously rectified buck-flyback converter is described which provides multiple synchronous regulated outputs. A synchronous buck converter provides the main output and a synchronous flyback converter, utilizing the primary inductor of the buck converter, provides the secondary output. The converter utilizes a split-feedback signal, whereby each of the regulated outputs provides a component of the signal and a switch controller synchronously activates and deactivates rectification switches based on the feedback signal, required output levels and load. The switches are synchronously controlled such that a power input switch is operated in anti-phase to a control switch for each regulated output.

Abstract: An auxiliary regulated power supply is described for use in a system having a main load directly connected to a main regulated power supply and an auxiliary load connected to the main regulated power supply by a line in which a voltage drop occurs. The auxiliary regulated power supply comprises a pair of input terminals for connection to the line, a pair of terminals for connection to a voltage source, a pair of output terminals for connection to the auxiliary load, a circuit for sensing the voltage at the output terminals, and an arrangement for boosting the output voltage at the output terminals from a secondary voltage source as necessary to maintain it at a level appropriate for the auxiliary load.

Abstract: A power supply for providing an ac/dc output to a load, includes a first source of dc power and an inverter that provides an ac output to the load. A second source of dc power is provided and selectably connects the first and second sources of dc power in series with the load when the output current reverses. In one embodiment the power sources are connected in series with every output current reversal. The first source of dc power is controllable and the magnitude of the dc current is responsive to a current reference signal. A control circuit provides the current reference signal, wherein the current reference signal is pulsed immediately prior to the ac output reversing polarity. The first source of dc power source preferably includes a buck converter that is switched at a variable frequency, depending upon the desired output current. In the event the user selects either an ac or dc electrode negative output a period of electrode positive dc energy is provided at start up to help establish the arc.

Abstract: A low loss power supply device for generating at least one output voltage (Ua) from an input voltage (Ue) having an absolute value which is higher than that of the output voltage. The power supply device has a low power loss and minimum space requirements. The power supply device includes a controller for generating the output voltage and a DC/DC converter having a primary circuit and a secondary circuit. The primary circuit voltage is a difference voltage (U.sub.c1) derived from the output voltage and the input voltage. The secondary circuit generates the output voltage. A further saving of components is achieved by forming the controller from the primary circuit of the DC/DC converter with the primary circuit connected in series with the secondary circuit.

Abstract: A continuous mode full wave power converter topology which integrates the buck-boost (flyback) and buck converter properties. The voltage transfer function is M=(D/(1-D)), characteristic of the buck-boost (flyback) converter. Characteristic of the full wave buck converter, the inductor current is source continuous during the alternate D intervals, source discontinuous during the simultaneous (1-D) intervals, and load continuous during both the D and (1-D) intervals.

Abstract: A system includes a computer main body, and an expansion unit detachably connected to the computer main body, for supplying a power to the computer main body and expanding a function of the computer. A power in the expansion unit is consumed in the expansion unit prior to power supply to the computer main body so as to stably supply a power to circuit components of the expansion unit. The expansion unit includes an expansion connector to which at least one expansion board is arbitrarily detachably connected, a power supply for supplying the power to the circuit components including the expansion circuit boards and to the computer main body, and a switch for detecting a power supplied from the power supply to the circuit components and stopping power supply to the computer main body by the power supply when the power exceeds a predetermined value.

Abstract: A controller for a two-switch buck-boost converter accomplishes one-at-a-time switch control by simultaneously employing an analog error signal to control one drive output and an analog inversion of that error signal, with respect to a voltage that is equal to the voltage excursion limit of a timing ramp signal, to control the other drive output. In a second embodiment of the invention, a controller employs a comparator to compare an analog error signal against a given voltage excursion limit of a timing ramp signal to perform the functions of determining which of two drive outputs is to be enabled to be modulated and of modifying the voltage excursion limits of the timing ramp signal such that the voltage excursion limit compared by the comparator is switched between two different voltage excursion limits.

Abstract: A voltage-doubler rectifier includes an ac fullbridge diode rectifier and a dc-to-dc converter having two output boost circuits. One of the output boost circuits is coupled between the rectifier and a dc link, and the other output boost circuit is coupled, with opposite polarity, between the rectifier and the circuit common. Two series-connected filter capacitors are also coupled between the dc link and the circuit common. In a preferred embodiment, the two output boost circuits each comprise either a series, parallel, or combination series/parallel resonant circuit and a rectifier. A switch is coupled between the junction joining one pair of diodes of the rectifier and the junction joining the two filter capacitors. For a relatively high ac line voltage, the switch is open, and the circuit operates in a low boost mode. For a relatively low ac line voltage, the switch is closed, and the circuit operates in a high boost, or voltage-doubling, mode.

Abstract: A dc converter for supplying an electronic device in which a feed voltage is summed with an additional voltage generated by rectification and wherein pulse-width control is provided at the primary side of the converter transformer. According to the invention, the additional voltage is generated by rectification in the same manner as the main output voltage is generated, i.e. the rectifier circuit outputting the additional voltage is similar to that outputting the output voltage.

Abstract: A power booster circuit is described. The booster circuit having amplifying circuitry comprises an input circuit, a switching circuit, and an auxiliary power circuit. The booster circuit is initiated by receipt of a signal by the input circuit. The amplifying circuit latches on when initiated by the switching circuit. The amplifying circuit produces a constant boosted power signal, using an auxiliary power circuit.

Abstract: An apparatus for AC line voltage regulation has an input port for connection to an AC source, an output port for connection to a load, and a transformer assembly connected between the input and output ports. The transformer assembly comprises a buck/boost winding and a primary winding wound about a common transformer core, and a switch arrangement for controlling the connection of the primary winding in circuit with the buck/boost winding. The switch arrangement is controlled by switch actuators responsive to a voltage sensor assembly to connect the primary winding in either of two possible conditions when the voltage is outside predetermined limits. The transformer assembly comprises either a step down transformer for reducing or bucking the output voltage or a step up transformer for boosting the output voltage according to the condition of the switch arrangement. The primary may comprise separate windings controlled by the switching assembly for connection in different configurations.

Abstract: An AC voltage regulator maintains a predetermined, desired output voltage despite changes in the input voltage, the load, or other operating conditions. The regulator generates an AC reference voltage signal of the same frequency and in phase with the input voltage, and having an amplitude proportional to the predetermined, desired output voltage. The AC reference voltage signal is compared instantaneously to a portion of the actual output voltage to determine an error between the actual output voltage and the predetermined, desired output voltage. The error is instantaneously corrected by altering the actual output voltage to conform to the predetermined, desired output voltage.

Abstract: A microwave oven for a camping or other vehicle includes a heating room in which an object is heating by applying microwaves thereto, a microwave guide to propagate the microwaves into the heating room, a magnetron to produce the microwave for the microwave guide, and a voltage supply device to supply the magnetron with an appropriate voltage. The voltage supply device includes a transformer to boost the three-phase AC voltage from an alternator mounted on the vehicle, and a rectifying circuit to rectify the three-phase AC voltage boosted by the transformer. The magnetron receives the voltage rectified. The heater terminal and other main terminal of the magnetron are connected to terminals of the battery mounted on the vehicle.

Abstract: At least two active conditioners are connected in series with a common DC source, and are mounted as a unit between two pairs of AC terminals to act either as a tie-in link between two AC power sources, as a buck/boost regulator between one AC power source and its load, or as VAR compensator as well as active power conditioner between phases of a multiphase AC option.

Abstract: A single power converter is capable of drawing low distortion current from an AC line and delivering DC or AC power to a load. The single power converter is used to independently control the input current and the output current. The power converter transformer has an output winding which is controlled by pulse-width modulation (PWM) and a frequency controlled boost winding for controlling input current.

Abstract: A switched-mode power supply provides a plurality of directly regulated DC output voltages. The power supply includes a first inverter-coupled transformer for providing first and second DC output voltages, with a feedback loop provided from a first output to the inverter for regulating the first DC output voltage. A second transformer is coupled across the first and second output lines of the first transformer and is further coupled across the second output lines by means of a switching regulator circuit including a second feedback loop for regulating the second DC output voltage. By proper selection of the number of turns of the second transformer, the regulator is capable of either substantially increasing the second output voltage when the switching device is on while lowering the output voltage very little when the switching device is off, or increasing the second output voltage very little with the switching device on while substantially lowering the output voltage when the switching device is off.

Abstract: In a buck-boost, switching regulator, separate signals are developed to control duty cycles of regulator switches. Control exercised by a pair of feedback-determined reference signal voltages through which a ramp signal is swept at inputs of separate comparators, comparator outputs control respective switches. A predetermined maximum voltage difference is permitted between the reference signal voltages. The reference used to control switching of one end of the regulator inductance is limited to a minimum voltage corresponding to a minimum duty cycle greater than 0% while the other reference is used to control the other end of that inductance and is limited to a maximum voltage corresponding to a minimum duty cycle less than 100%. A current limiting feedback from one of the switches is operated in response to current in excess of a predetermined level to force the ramp signal to a level corresponding to 0% duty cycle for both switches at the same time.

Abstract: A regulated power supply for supplying DC output voltage and current to an electronic control system of an internal combustion engine, designed especially for automotive applications and cold cranking conditions encountered therein, is disclosed. The power supply has a series switching regulator section having a transformer provided with two windings, and a shunt switching regulator section that shares the transformer with the series regulator section. When normal battery voltages are available, the power supply through its series regulator section operates in a voltage dropping mode, intermittently passing current through the primary winding of the transformer to maintain the desired output voltage. When low battery voltages are encountered, such as during cold cranking conditions, the shunt regulator section of the power supply operates in a voltage boosting mode to maintain the desired output voltage.

Abstract: This disclosure relates to an electrical power transfer system for matching a load to a DC source such as a solar array. The system tracks the power output of the source under varying operating conditions and matches the load to the source to maintain peak power conditions. The system senses the voltage and the current of the source, incrementally changes the volt-ampere operating point of the source and thereby changes its incremental resistance, and adjusts the load to the level where the ratio of the DC source voltage to the DC source current is substantially equal to the incremental resistance.

Abstract: Improvement in a regulated D.C. power supply having a conventional main transformer with a center tap secondary and rectifying elements, the improvement comprising a buck-boost transformer, and a regulating device, the buck-boost transformer being of the same type construction as the main transformer and also having a center tap secondary, the secondary of the buck-boost transformer being connected in circuit with the secondary of the main transformer and the rectifying elements so that the center taps of the main and buck-boost transformers are utilized as positive and negative output terminals for the power supply, connecting the input of the main transformer to the input of the regulating device and the output of the regulating device to the primary of the buck-boost transformer, whereby a regulated D.C. power output is provided by the buck-boost transformer bucking or boosting the main transformer.

Abstract: A D.C. power supply (10, 44) having an auxiliary bridge rectifier (14, 38, 48) connected in series with a primary bridge rectifier (12, 46) is disclosed. The auxiliary bridge rectifier (14, 38, 48) "floats" above the potential of the primary bridge rectifier (12, 46) furnishing additional voltage at the D.C. power supply output (20, 22; 56, 58) whenever the A.C. mains voltage input to the main bridge rectifier (12, 46) drops below a predetermined value. In one embodiment of the present invention, a series of SCR's (26, 28) arranged in three-phase configuration perform the rectification and regulation functions of the primary bridge rectifier (12, 46) and the auxiliary bridge rectifier (14, 48). In an alternate embodiment of the present invention, paired SCR's (40) and diodes (42) are arranged in a half-controlled auxiliary bridge rectifier configuration (38). Individual firing angles for the various SCR's (26, 28, 40) are computed as a composite of several factors, including a firing delay factor .alpha..sub.

Abstract: A boost power supply having a full-wave rectifier driving an inductor, diode, and the parallel combination of a filter capacitor and load. A shunting switch connected between the inductor and diode is periodically closed to draw current through the inductor, thereby charging the inductor. The switch is then opened so that the inductor, while discharging, generates a relatively high voltage which is applied to the load and filter capacitor through the diode. The shunting switch is opened and closed in a manner which causes the input current to follow a sinusoidal waveform in phase with the input voltage with an amplitude that maintains the output voltage of the power supply constant. Specifically, a harmonically pure sinusoidal waveform is multiplied by a voltage inversely proportional to the output voltage.

Abstract: A device is proposed for generating specific electrical voltage values for consumers associated with an internal combustion engine. The device also encompasses a voltage elevating circuit which can be switched on in the vicinity of the minimum voltages for the consumers. This means that this voltage elevating circuit does not need to be switched on continuously during engine operation, but rather only at times of increased power needs. The voltage elevating circuit has a series circuit of a coil 20 and a diode 21 in a voltage supply line, and the connecting point of these two components is briefly closed off from the other supply line in a clocked manner. The activation of the voltage elevating circuit can be switched on and off in accordance with the input and output voltages and in accordance with the maximum permissible switching current. Depending on the clock frequency of the switch 23, the line inductance of the supply line suffices as an inductance 20.

Abstract: A buck boost type noninverting transformerless switching regulator utilizes two synchronized switches operating at either the same or different duty cycles to independently control energy storage and energy delivery from a two terminal inductor element to the output load. A wide range of output voltage is available and is continuously regulated.

Abstract: A transistorized power supply for providing a constant voltage to a load. A series regulator interposed between a d.c. input voltage source and the load to regulate the d.c. output voltage. A d.c. to d.c. converter serially connected between the d.c. input voltage source and the series regulator. The d.c. to d.c. converter is selectively actuated to supplement the d.c. input voltage when the d.c. input voltage falls below a predetermined value in order to maintain a constant voltage across the load.

Abstract: A regulated power supply includes an oscillating inverter circuit for generating a high frequency square wave signal that drives a saturable reactor which pulse-width modulates the square wave as a function of a control current through a control winding on the saturable reactor. The output voltage generated by the power supply in sensed by a feedback circuit and fed back as a modulating signal of the control current through the saturable reactor control winding to vary the power transferred by the saturable reactor to an output transformer. The variation in power supplied to the output transformer compensates the output voltage as sensed by the feedback circuit. A protective circuit is provided to sense an output overvoltage condition and inactivate the power supply by terminating the oscillation of the inverter.

Abstract: The unbalance in currents flowing alternately in the two halves of a doubended, push-pull inverter is obviated by means of a parallel resonant network, comprised of an inductor and capacitor, placed in series with the power supply voltage applied to the center tap of the inverter transformer primary winding. The network component values are selected to provide relatively a high impedance of the inverter fundamental operating frequency while providing a low impedance at twice the fundamental operating frequency.

Abstract: A power supply device which boosts and stabilizes the voltage of a dc power supply includes an oscillator circuit connected to the dc power supply, a voltage multiplying rectifier circuit which rectifies the output of the oscillator circuit and boosts the voltage and an oscillator control circuit which monitors the boosted voltage and stabilizes the boosted voltage by on-off control of the oscillator circuit. The voltage multiplying rectifier circuit includes a voltage storage element, such as a capacitor connected in parallel with the load driven by the power-supply device. When the output voltage of the device exceeds a predetermined reference voltage, the oscillator control circuit turns the oscillator circuit off. The voltage storage element is thus no longer supplied with electric energy and begins to discharge through the load thereby lowering the output voltage of the device.

Abstract: A voltage regulated DC to DC converter is disclosed which is operable over a wide range of input voltage including voltages greater or less than the desired output voltage. The converter uses an inductor and a capacitor as storage elements, the inductor being composed of two windings having a common junction. A transformer having a center tap connected to the common junction of the two windings of the inductor is connected at either end of its winding to ground through controlled switches. One winding of the inductor and either end of the transformer winding are connected by respective power diodes to the capacitor which supplies the output voltage to a load. The other winding of the inductor is connected to a fourth power diode as a clamping diode. Input voltage is supplied to the inductor through a third controlled switch.

Abstract: This closed loop potential regulated ac-dc power supply comprises a power transformer having two secondary windings and a compensating transformer having two compensating windings connected individually in series circuit with the principal power supply secondary windings. The other secondary windings on the power transformer supply exciting windings for compensating variations in output potential by control of the compensating transformer control circuitry which has an input circuit connected across the load and an output for varying the ac supply to the exciting windings inversely of variations in load potential. A differential amplifying circuit is used for determining the load potential error and driving a transistor effectively to insert a dc component in inverse feedback relationship into the exciting windings of the compensating transformer. As the output potential error increases, the control current is decreased, and conversely.

Abstract: The present power supply has two step-up transformers with their respective primary and secondary windings series-connected. A half-wave rectifier tube and a filter are connected to the transformer secondary windings to rectify the current induced in them and to smooth out fluctuations in that current. One or more additional step-down transformers are provided, each having a primary winding that may be switched in series with the first-mentioned primary windings or disconnected from them and a secondary winding connected across a lamp. These additional transformers, when connected in the circuit, reduce the D.C. output voltage of the power supply and enable this output voltage to be selectively adjusted in steps. The lamps indicate visually which of these additional transformers are connected in the circuit.

Abstract: A voltage supply circuit comprises an input for receiving a DC input voltage having one of plural possible levels; a DC-AC inverter for inverting the DC input voltage and which includes a boosting transformer having a winding with end terminals and an intermediate terminal and an inverter drive circuit for providing an AC current to the transformer; a connection between the input and the intermediate terminal of the boosting transformer for applying the DC input voltage to the latter; and a control circuit for controlling the inverter drive circuit, and which selects between a first condition, in which the inverter drive circuit is made operative so that a boosted voltage is provided at one end terminal of the boosting transformer, and a second condition, in which the inverter drive circuit is made inoperative, so that the DC input voltage introduced at the intermediate terminal is provided as a DC output voltage at the end terminal of the booster transformer.

Abstract: A sinusoidal-like output is obtained from a source of DC by adding the outputs of two or more DC to AC inverters, producing flat-topped pules combining to provide a normally near ideal stepped sinusoidal-like waveform, with the output of a buck-boost circuit which produces bucking or boosting outputs of one polarity or another when voltage regulation is called for or a zero output when no regulation is called for.

Abstract: A voltage regulator for providing a predetermined output voltage from an unregulated voltage input is described where the output voltage is compared with a reference voltage to generate one or more control signals which in turn activate boost regulators which inject voltage onto the output. Each boost regulator utilizes a transformer for injecting the voltage onto the output and a bypass diode across the transformer to permit the input voltage less the diode voltage drop to appear at the output when the boost regulator is not activated.

Abstract: A highly efficient tuned oscillator ballast circuit especially suitable for a fluorescent lamp load includes an oscillator circuit coupled to a pulsed DC potential source and having a tuned output circuit coupled to a load circuit, to a drive circuit for the oscillator which is dependent upon current flow in the load circuit and to a rectifier and charge storage and isolation and applying network coupled to the pulsed DC potential source and providing energy thereto whenever the potential decreases below a given reference level. A transient compensating circuit to protect the oscillator components from initial or "start up" transients is also included.

Abstract: A highly efficient tuned oscillator ballast circuit especially suitable for a flourescent lamp load includes an oscillator circuit coupled to a pulsed DC potential source and having a tuned output circuit coupled to a load circuit, to a drive circuit for the oscillator which is dependent upon current flow in the load circuit and to a rectifier and charge storage and isolation and applying network coupled to the pulsed DC potential source and providing energy thereto whenever the potential decreases below a given reference level. A transient compensating circuit to protect the oscillator components from initial or "start-up" transients is also included.

Abstract: A high power factor conversion circuit suitable as a ballast circuit for lamps includes a full-wave rectifier coupled to an AC potential source and providing a pulsating DC potential. A high frequency inverter is coupled to a load circuit and to a feedback rectifier circuit supplying a rectified high frequency potential to an energy storage feedback circuit which provides energy in a manner to inhibit a decline in the pulsating DC potential thereby providing a substantially uniform DC potential to the high frequency inverter.

Abstract: There is disclosed a voltage multiplier having a capacitor-diode voltage multiplying network which is fed with voltage pulses from a d-c source through a first switching means. Pulses of a second polarity are also supplied through a second switching means to the input of the capacitor-diode voltage multiplier from a second d-c source whose voltage is adjustable to change the voltage of the pulses of second polarity. The switching means are alternately rendered conducting by signals from a control circuit. The second d-c source may be controlled by a voltage comparator which compares the output voltage of the capacitor-diode voltage multiplier to the reference source.

Abstract: A typical "stand alone" precision power DC to AC solid state converter reres a higher DC supply voltage than is usually available from its utility power sources. The disclosed invention is a voltage boost circuit that provides the DC-bus voltage amplitude for precision power DC to AC solid state converters by transforming only the difference between the available raw power DC voltage bus and the required precision DC voltage amplitude. This DC voltage difference obtained by the circuitry of this invention is boot-strapped to the available DC bus to obtain the required precision DC voltage.