Abstract: A load is supplied by a transformer supplied via a voltage regulator and thyristor network. The thyristor network and regulator are simultaneously controlled to respond to changes in the load and in practice the thryistors respond rapidly and are re-adjusted as the regulator is inherently more slowly adjusted. The result is that the thyristors produce minimum reflected harmonics overall in the mains and an optimum power factor can be achieved for each power setting.

Abstract: A low voltage two wire dimming circuit comprises a voltage compensating circuit for regulating the RMS value of an AC voltage applied to a load and a correcting circuit for eliminating damaging DC current that may flow through the load. The voltage compensating circuit adjusts the firing angle of an electronic switch disposed in the dimming circuit to compensate for fluctuations in the AC supply voltage. The correcting circuit advances or retards the firing angle during selected half cycles to correct for asymmetries in the AC load voltage waveform caused by excessive DC current. According to the invention, there is also provided a two wire low voltage dimming circuit without voltage compensation but having improved dimming ability at low load currents and improved resistance to the flow of damaging DC currents.

Abstract: Voltage drop developed across a transformer primary winding coupled in series with a primary a.c. power circuit including an a.c. power source and an a.c. load is utilized to provide a secondary source of a.c. power having secondary voltage level stability which is substantially independent from otherwise influential changes in primary power circuit levels. Secondary power stabilization is mainly established by constant voltage limiting of the primary winding excitation by the forward voltage drop developed across an arrangement of semiconductor junctions coupled in parallel with the primary winding. The transformer may be used to change the source level of the secondary a.c. power which is produced, and to obtain electrical isolation between the primary power circuit and any ancillary circuits coupled with the secondary a.c. power source.

Abstract: A circuit for controlling an AC current through a load. The load, e.g. a motor (3), is connected in series with a first triac (7) between two terminals (1, 2) adapted for connection to an AC supply voltage. A series circuit of a capacitor (6) and a parallel circuit consisting of a first (14) and a second (5) resistor is connected parallel to the first triac. The control electrode of the first triac is connected to the capacitor by means of a series circuit of a third resistor (9) and a second triac (10). A control electrode of the second triac is connected to the capacitor by means of a diac (8).

Abstract: A.c. line operated controller which provides solid-state switching of a.c. power flow, together with producing a supplementary source of low d.c. power for operation ancillary circuits. Operation is obtained through electrical connection that is in series with only one side of the a.c. power circuit. Device utilizes a thyristor for a.c. power switch control. A small residual potential which is devised to appear across the ON-state thyristor is rectified to produce the low d.c. power level. When the thyristor is OFF, the line voltage potential across the thyristor is reduced and rectified to produce the low d.c. power level. Turning the thyristor OFF is attained by current starving of the thyristor gate electrode by a gate shunting semiconductor switch. Device is shown to be utilized in "two terminal" apparatus producing time delayed switching of a light, as a controller for producing the illusion of a flickering flame from an ordinary light bulb, as a light flasher, and as a "touch-controlled" a.c.

Abstract: The proposed invention is an energy saving load control device primarily intended for inductive loads (i.e., fluorescent lighting, motors, etc.) operating from an alternating current (AC) source. The proposed device switches the load voltage off at arbitrary positions in the sine wave and simultaneously provides a commutating path for any inductive current. By switching the load voltage on and off and providing a commutating current path reduced energy consumption is realized.

Abstract: An AC power control apparatus including a power circuit for supplying an AC current to a load, and a circuit connected to a power supply, for initiating energization of the load at a zero-cross point of an AC current waveform. A control circuit for controlling the change of energization time between a current turn on time to a current turn off time in units of AC waveform cycles, and a detector for detecting an AC zero level. From a given polarity of the AC current waveform, the initiating energization of the load and deenergization of the load at a zero-cross point of the AC current waveform is from the same polarity as the given polarity of the AC current waveform.

Abstract: A circuit arrangement for providing in a fail-safe manner an alternating output signal to a load, e.g. in a railway signalling system. The load is connected across a first winding of a transformer, to opposite ends of a second winding of which transformer is connected a bi-directional current switching circuit. First and second modulated signal sources are connected to the bi-directional switching circuit. Each of the signal sources modulates a carrier signal with a modulation signal, the outputs of the signal sources being out of phase with respect to each other. The bi-directional switching circuit is operative to switch current through the second winding alternately in opposite directions at the frequency of the modulation signal. The circuit arrangement is such that if any of its components fails to operate correctly, the output appearing across the first winding is no greater than a threshold level.

Abstract: A proximity switch e.g. for a domestic a.c. supply is connected in-line e.g. in the live line of the supply between live and switch live terminals. No direct connection is made to the neutral line. Switching is performed by a triac T which receives a gate input 17 from a control circuit K that includes a proximity switch (FIGS. 5, 6). The control circuit K has a power supply comprising a charge storage capacitor C1 that is charged from the live terminal through a first impedance (diodes D3, D4) and a unidirectional first path through diode D1 when the triac T is conductive. When the triac T is switched to a non-conductive state, the capacitor C1 is charged from the switch live terminal through a second unidirectional path including diode D1 and a second impedance R2.

Abstract: A multiple location system is provided for controlling application of alternating-current power to a load. The system employs a dimming system in combination with one or more switches. In one embodiment, the system includes an override, so that a switch can provide power to the load even after the dimmer has turned the power off. In another embodiment, the dimming system includes an actuator, and the value of power to the load is determined substantially immediately upon setting of the actuator.

Abstract: The invention relates to a two-wire switch for connecting a load to an ac ltage source, and, in particular, to a two-wire switch with an auxiliary voltage source. A capacitor acting as charge storage device can be charged by the auxiliary voltage source which operates on the principle of phase angle control. In accordance with the invention, a series connection comprising a threshold element which can be brought into the conducting state when there is a prescribed minimum voltage across the capacitor, and a diode is inserted into a control current circuit for a controllable semiconductor device on the input side of the bridge.

Abstract: An economical astable multivibrator circuit provides a variable frequency, variable duty cycle digital signal for controlling a solid-state relay to provide power proportioning. An optical isolator receives analog input signals and converts those signals into a variable resistance signal for altering the RC time constant of the charge/discharge timing circuit. The controller is capable of driving several solid-state relays simultaneously and includes a powerstat adjustment for manually adjusting the range of power delivered to a load.

Abstract: An electronic switching device having a detection circuit or input circuit powered by an external source and load is described. The external source and load are in a series circuit with a power switching element which thereby provides switch controlled power in response to an output signal generated from a detection circuit. A current limiting device is connected in series with the power switching element, and an excess current detection circuit responds to excessive current flowing in the aforemention series circuit to interrupt the power switching element when an abnormally large current is passed. Circuitry is provided for holding the current limiting device in its operable or current interrupting state for a predetermined period of time.

Abstract: A switching arrangement for full-wave power control comprising a triac (2), the control electrode of which is preceded by a trigger diode, the control voltage being taken from an RC section having at least one potentiometer (9), which effects a phase shift in the firing time as a function of the position of the potentiometer (9), is improved by the RC section (9, 10) being connected to a constant voltage source. This consists of two Z diodes (6) which are connectd in opposition and which are advantageously bridged by means of an adjustable voltage divider (7, 8), in such a manner that the RC section (9, 10) is connected to an adjustable part voltage. Instead of bridging the triac (2) for full drive, as usual, the trigger diode (11) is connected to a special bias resistor by means of a switch (13). According to a preferred embodiment, the resistors of the switching arrangement consists of a low-temperature thick-film paste printed on a hard paper board (see drawing relating to this).

Abstract: A multiple location system is provided for controlling application of alternating-current power to a load. The system employs a triac as a power carrying device, the gate control circuit for which has been modified to include auxiliary switching. Potentiometers are disposed at various different locations for determining, responsively to the setting or positioning of an actuator, such as the slide control of a linear potentiometer, the magnitude of respective control signals substantially immediately upon setting of the actuator. The signals are mutually exclusively applied to control the triac in accordance with which of the actuators is being set. Alternatively, the control signals can be applied in accordance with which one of a series of take-command switches (one for each location) was last operated. In either case, only two wires are necessary to connect the different locations to one another. In one embodiment, the actuator controls a pair of momentary-close switches associated therewith (e.g.

Abstract: A circuit for controlling the initiation and operation of a phase control circuit employed in voltage regulation to a load such as dimming lights. The circuit uses a power semi-conductor which is triggered by a "walk-in" circuit. The "walk-in" circuit includes a regulator diode across a diode bridge which stabilizes the output of the load, such as a level of lighting.

Abstract: A two-terminal line-powered control circuit is disclosed in which a triac is used to switch AC power to a load. When the triac is not conducting, a portion of the voltage appearing across it is rectified and filtered and used to supply power to a radio control circuit. When the triac is conducting, the voltage appearing across inverse-parallel connected diodes, which are in series with the triac, is stepped-up using a transformer, then rectified and filtered and used to supply power to the radio control circuit. The radio control circuit is in turn used to control the operation of the triac in response to a remotely transmitted radio signal.

Abstract: A power control system for electrical apparatus, in which a unidirectional rectifying device is connected to one of a plurality of loads connected mutually in parallel, an ignition circuit comprising a plurality of resistors is connected between the loads and a switching element whose conduction phase is controllable, and at least one of the resistors in the ignition circuit is connected through the unidirectional rectifying device to the said load, whereby the power supply to each of the plurality of loads can be controlled in an individual manner by means of the single switching element.

Abstract: An electronic switch with CSE wiring, especially a triac, has a load connected in series therewith to an a-c voltage network. A rectifier bridge circuit has its a-c terminals connected into the driving circuit of the electronic switch. The d-c terminals of the bridge circuit are connected to a light-emitting diode poled in the conduction direction. Since the firing current for the switch is periodically repeated, the light-emitting diode indicates the switching state of the triac since the brief pauses without current of the LED are not perceived by the human eye.

Abstract: In a transformer having a primary winding which is connectable to an a.c. voltage source via switch means which opens and closes at a controllable frequency, there is connected in parallel with the primary or secondary winding of the transformer a circuit which for at least a part of the time during which the switch means opens maintains magnetization of the transformer in a direction opposite to the direction of the magnetization caused by the subsequent closing of the switch means.

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 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: A dimmer switch assembly consists of a conductive yoke which has two insulation housings connected thereto which carry respective subassemblies for the dimmer switch. A cavity in the first housing receives the main power semiconductor device of the dimmer switch. The power semiconductor device is thermally connected to the yoke through a thin electrically insulative tape and has an active, non-electrically isolated, heat sink. A biasing spring within the first housing presses the power semiconductor device toward mechanical engagement with the yoke. The first housing assembly is fastened to the yoke by conductive eyelets which are insulated from the power semiconductor by the first insulation housing.

Abstract: A dimmer switch assembly consists of a conductive yoke which has two insulation housings connected thereto which carry respective subassemblies for the dimmer switch. The first insulation housing contains a rotatable push shaft. Shaft rotation rotates a resistor plate having a resistive pattern on its surface relative to fixed resistor contacts. A biasing spring biases the shaft to an outward position relative to the conductive yoke. A cavity in the first housing receives a main power semiconductor device of the dimmer switch. The power semiconductor device is thermally connected to the yoke through a thin electrically insulative tape and has an active, non-electrically isolated, heat sink. A biasing spring within the first housing presses the power semiconductor device toward mechanical engagement with the yoke. The first housing assembly is fastened to the yoke by conductive eyelets which are insulated from the power semiconductor by the first insulation housing.

Abstract: A system of controlling the operation of an AC load with a switch placed in series with the load, which switch is itself operated by dc control logic powered by power loss experienced by the switch which the logic controls. Numerous elements in the control system perform multiple functions allowing the control logic to remain alive during both the on and off mode of the switch without power being provided to the logic by separate conductors to the AC power source, such that the control system is completely self powered and self regulated by simply placing the system, with two wires, into a series loop with the AC power source and the load.

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 system for providing a firing signal to an electrical power switch at a selectable instant during each cycle of a periodic waveform electric power source. A comparator receives a signal varying monotonically with time and a control voltage as inputs, and produces the firing signal at such time that one of these inputs first exceeds the other. The control voltage is clamped to a predetermined value to provide a minimum power output from the electrical power switch.

Abstract: A static high voltage switch which can be constructed in miniaturized form and having a high degree of reliability, it comprises a bridge of switches, such as thyristors, each controlled by a secondary winding of a transformer whose single primary winding is connected to the secondaries by toroidal cores. Each toroidal core comprises a secondary winding. The primary winding is constituted by a high voltage cable element, which passes axially through the cores.

Abstract: Power supply and method in which the primary current to a transformer is switched on and off to maintain the output of the supply at a desired level. When the energizing current is off, an additional current is applied to the transformer to maintain the core at a level of magnetization such that the full hysteresis characteristic of the transformer is utilized during the next half cycle of operation.

Abstract: A phase-fired triac controller used to control the supply of voltage to a load. A system has been devised that controls the level of voltage at the gate triac to avoid breakdown of this element.

Abstract: A voltage reducing circuit device for reducing the RMS value of an incoming AC voltage is disclosed herein. This device is especially suitable for reducing line voltage applied to a load requiring lower voltage. In a preferred embodiment, the device is one which allows a domestic made 115 VAC small heating apparatus, such as a hair dryer, to be used in foreign countries where the 230 VAC service is available. In any case, the device is one which is relatively insensitive to fluctuations in line voltage and to changes in frequency.

Abstract: Intelligent load control and switching circuits for facilitating the switching and control of the power consumption level of at least one power-consuming load, responsive to a signal, having a programmable amplitude or programmable pulse-width, provided thereto. The load control and switching circuit not only controls the coupling of a power source to a power-consuming load, but also controls the portion of the source waveform cycle during which the load is coupled to the source, to control the average power consumption thereof. Several embodiments of load control and switching circuitry, as well as power supplies for providing operating potential thereto, as disclosed.

Abstract: Apparatus facilitating the switching and control of the power consumption level of at least one power-consuming load remotely located from a central facility. Load switching and power-consumption control commands are sent from the central facility to each of the remote locations to provide an analog signal having a programmable amplitude or programmable pulse-width thereof to an intelligent load control and switching circuit. The load control and switching circuit not only controls the coupling of a power source to a power-consuming load, but also controls the portion of the source waveform cycle during which the load is coupled to the source, to control the average power consumption thereof. Several embodiments of load control and switching circuitry, as well as power supplies for providing operating potential thereto, are disclosed.

Abstract: A circuit arrangement contains an oscillator for producing high frequency pulses, a gate circuit, a pulse transformer and a triac. The high frequency pulses can be connected to the primary winding of the transformer by way of the gate circuit. The secondary winding of the transformer is connected in the control circuit of the triac. The line voltage load is connected in the output circuit of the triac. A switch is arranged at the output of the gate circuit and is connected to the primary winding of the transformer. The switch is closed only during the presence of one polarity of the pulses so that a current can only flow through the primary winding of the transformer during a corresponding interval.

Abstract: A circuit for controlling the application of alternating current power to an apparatus provides a triac having a pair of main terminals adapted for being coupled in series between the apparatus and a source of alternating current power, the triac also having a gate terminal, nonregulated direct current power supply adapted to receive alternating current power from the source thereof, the power supply including a rectifier and a filter and having a pair of output terminals for distributing direct current power, circuitry for maintaining an approximately constant load on the nonregulated direct current power supply and for switching current therefrom to the triac gate terminal including a semiconductor junction switch having a gate terminal, a first main terminal coupled to one output terminal of the power supply and the triac gate terminal and a second main terminal coupled to the other output terminal of the power supply, and circuitry coupled to the switch gate terminal for activating and deactivating curren

Abstract: A power supply circuit impresses a signal supplied by a pulse generator (28) at one frequency on an alternating current such as a standard AC signal at 115 volts RMS and 60 hertz by utilizing a single switching transistor (Q1) coupled between the pulse generator (28) and a current-directing element (14) which, in turn, is serially coupled between a source (10) of the alternating current and a load (18). The resultant bidirectional output voltage across the load (18) may be rectified and averaged to produce a substantially constant DC voltage whose level is regulatable by controlling the duty cycle of the pulse generator (28).

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.