Abstract: Apparatus for use in an electrical power generating system including a generator for supplying an A.C. output voltage to a load on a set of lines and a circuit responsive to the A.C. output voltage for producing a regulating voltage, the generator having a winding the D.C. energization of which controls the A.C. output voltage. The apparatus controls the energization of the winding and includes a switching circuit adapted to be connected across a resistance and which when rendered conductive bypasses the resistance to couple the voltage regulating circuit to the winding with negligible loss of energy. The switching circuit is combined with a circuit that produces a signal when an increase in the A.C. output voltage exceeding a preselected parameter occurs, and with another circuit that renders the switching circuit nonconductive in response to the signal thereby causing the resistance to consume energy from the winding. Methods of operation of the apparatus are also described.

Abstract: An electronic dimming apparatus includes a semiconductor power controller which couples a lamp to an alternating current source and variably controls the average power supplied to the lamp by adjusting the relative proportion of each half-cycle in which the power controller is in a conductive condition. The semiconductor power controller is controlled by the output of a transition controller which in turn is connected to a triggering circuit. The triggering circuit is responsive to a first input condition corresponding to desired average power and also responsive to the zero-crossing of the alternating current waveform. The transition controller gradually changes the condition state of the semiconductor power controller between non-conduction and conduction and controls the voltage across the lamp load to maintain a stable rate of voltage change despite lamp impedance variations, thus reducing electromagnetic interference.

Abstract: Alternate polarity pulses of current are fed to a load L1A by charging a capacitor C5A alternately in different directions and closing unidirectional switches V2A and V3A at appropriate times to discharge the capacitor C5A through the inductor L1A. This arrangement is considered superior to an alternative system in which different capacitors are charged with different polarities to produce the different pulses. In the latter system the arrangement of switches needs to be such that the closing of one produces transient voltages which might cause the other switch to operate when it is not required to do so. In the illustrated system the switches V2A and V3A, being connected in parallel, do not suffer from this problem. In an alternative system the switches V2A and V3A could be replaced by a single bi-directional switch.

Abstract: A monitoring circuit for monitoring the condition of, for example, a remotely situated structure is shown as having a transducer responsive to the occurrence of a preselected condition in the remotely situated structure and effective for causing a signal indicative thereof; timing apparatus actuated upon the occurrence of the signal effective to establish the validity thereof; a power circuit electrically closed upon the expiration of a time span established by the timing apparatus, and sensory warning apparatus actuated upon electrical closure of the power circuit.

Abstract: A phase control device for regulating illumination of a fluorescent lamp means is disclosed, which includes a thyristor, an ignition circuit therefor and a delay circuit for providing a time delay of a predetermined period after a power switch of a driving circuit of the fluorescent lamp means is closed so that the ignition circuit is actuated to make the thyristor operative to thereby regulate the illumination thereof only after the fluorescent lamp means warms up sufficiently before the phase control therefor is introduced.

Abstract: Ramp generating circuits, for synchronizing SCR firing control signals to the phase-varying signals derived from a three-phase AC power source, each have a compensating circuit connected across an operational amplifier and a capacitor to control the peak value of the ramp signal generated at the output of the operational amplifier. The compensating circuit maintains the peak value of the ramp signal close to its calculated value despite variations in the actual value of the capacitor from its nominal or rated value and despite changes in power line frequency between 50 hertz and 60 hertz. The compensating circuit includes a T-section passive network, a voltage-following amplifier and several feedback resistors connected from the output of the operational amplifier to its inverting (-) input. This compensating circuit increases or decreases charging current to the capacitor according to the type of compensation that is necessary.

Abstract: The power delivered from a three-phase A-C power source and through a network of SCR's (connected, for example, to form a full wave rectifier bridge or to provide an A-C switch) to a load circuit is adjusted by controlling the conduction angles of the SCR's. The control is achieved by developing, from only one of the three alternating phase voltages provided by the A-C power supply, a reference square wave signal of the same frequency and whose amplitude excursions are precisely synchronized or keyed to the zero voltage crossings of the selected phase voltage, even though that phase voltage may include undesired harmonics, noise, transients or other distortion components.

Abstract: A circuit for supplying first and second currents to a load comprises two current generators for providing those currents during first and second time intervals and a resistance through which those currents flow. Two control potentials developed by two semiconductor junctions are applied across the resistance. First and second control circuits control the two current generators so that the first and second currents are provided during the first and second time intervals, respectively. The current supply circuit is useful in a multivibrator wherein the timing capacitor thereof is the load to which the first and second currents are supplied.

Abstract: The invention is a controlled ferroresonant power supply with an improved feedback circuit resulting in improved output stability. The feedback circuit is responsive to the low voltage secondary output of the power supply to provide a variable output signal to activate the switch which controls the resonant winding circuit. The improved feedback circuit is responsive to the rectified AC low voltage secondary output for only a portion of its frequency period.

Abstract: In a pump drive circuit, a power source voltage signal supplied to the pump is phase-controlled by a triac connected between the pump and the power source. The period of triggering the triac is determined by a time constant circuit of a UJT, a capacitor and a resistor circuit. The power source voltage signal has its frequency determined by a frequency discrimination circuit. The resistance value of the resistor circuit is selected in accordance with the result of the discrimination. Accordingly, the pump is applied with a voltage signal the phase of which is controlled in accordance with the power source frequency, and is thus driven to maintain a predetermined output.

Abstract: A solid-state dimmer control circuit using opto-isolators, whereby the effective power to be supplied to a load is selectively varied. The opto-isolators couple a variable pulse switching circuit to a full-wave switching circuit which includes back-to-back silicon-controlled rectifiers. The variable pulse switching circuit is connected to means for generating a selectively variable control signal that is proportional to the power to be supplied to the load. A single a.c. power source is provided both switching circuits.

Abstract: The control circuit is preferably provided in an integral unit with a momentary on-off switch, preferably inside a switch housing box and adapted to replace a common wall switch to provide for the automatic turn-off of the light or other load operated by the switch after a presetable period of time. The circuit is constructed so as not to require a third wire (usually a power lead) at the unit. The use of low power logic circuit controls, employing preferably CMOS chips enables use of a capacitor storage element of manageable size, with very low power consumption of the circuit in its "off" state. The "on" duration of the light is adjustable over a suitable time range and the circuit is further characterized by a "flashing" period preceding total turn-off.

Abstract: A contactless motion detector, including an oscillator sensitive to an approaching metallic element, includes an electronic switch such as a thyristor triggerable by an output signal from a demodulator comprising a storage capacitor which is alternately chargeable and dischargeable, preferably with constant current, during each cycle of a high-frequency voltage generated by the oscillator. The oscillator voltage is compared with a reference voltage by means of a differential amplifier causing the flow of a charging current into the capacitor when the oscillator voltage exceeds the reference voltage whereas a discharging current flows out of that capacitor in the opposite case. The reference voltage is so chosen that the capacitor charge rises in the course of a few cycles above a predetermined threshold when the oscillator voltage is high but remains below that threshold when it is low.

Abstract: A phase fired controller is provided for eliminating large shifts in the firing angle due to line voltage variations. Another advantage of the controller is that variations resulting from parts tolerances are reduced substantially. This is accomplished by controlling the output of a capacitor that supplies a voltage to a comparator. The system has particular utility when used as a dimmer controller of an electrostatic copier.

Abstract: An improved proportional A-C power control for use in welding apparatus and other equipment to obtain smooth and continuous phase control particularly with inductive loads and requiring minimized current demands on the control circuit voltage source.

Abstract: To turn a thyristor, particularly a high-voltage thyristor, ON, and to connect the thyristor and the utilization circuit to a power source, a charge capacitor is connected to a charging circuit to charge the capacitor when the thyristor is blocked or in OFF state. A controlled switch, typically a transistor 20, is connected to the charge capacitor 19 and connects the charge capacitor to the gate electrode of the thyristor, when the controlled switch is turned ON; a control circuit is connected to the controlled switch which includes an opto-coupler 28 to control its conduction. Preferably, a threshold sensitive element such as a Zener diode 25, or a four-layer diode 30, is included in the controlled switch transistor base circuit to provide for sharp turn-on characteristics.

Abstract: A power control circuit has a thyristor bridge interposed between a.c. buses connected to an a.c. power supply and a load. The firing circuit for the thyristors of the bridge includes a light actuated controlled rectifier for generating firing pulses. Two series connected resistor-capacitor pairs are connected in series across the a.c. buses. Taps intermediate the resistors and capacitors provide an energizing anode voltage to the controlled rectifier reduced with respect to the a.c. voltage in the buses. The voltage reducing and capacitive properties of the pairs render operation of the controlled rectifier immune to transient voltage spikes in the a.c. buses.

Abstract: A field effect transistor is used to short circuit the timing capacitor of a thyristor when power is interrupted or removed. The short circuiting of the timing capacitor prevents the residual capacitor charge from being added to a new charge after an interruption so that the early firing of the thyristor is avoided and component damage is prevented. Because capacitor charging always starts at zero voltage when the field effect transistor is used, hysteresis at low voltages is greatly improved.