Abstract: Operation of an electrical load controller includes predetermining a duration of time based at least in part on a frequency of an alternating current (AC) waveform, the AC waveform oscillating though full cycles, selecting a detection window of time equal in duration to the predetermined duration of time, the selected detection window extending from a selected first time to a selected second time and straddling an expected time of a next zero-crossing of the AC waveform, monitoring a zero-crossing signal for a zero-crossing indication, of the next zero-crossing, occurring within the selected detection window, ascertaining a time of the next zero-crossing based on the monitoring, and selectively controlling a supply of AC power to a load, wherein the controlling uses the ascertained time of the next zero-crossing of the AC waveform to fire a switching circuit of the electrical load controller.

Abstract: A driver chip for a half-bridge circuit includes a drive module and a programming module. The drive module is configured to receive an enabling signal and at least one input signal. The drive module outputs a high-side output signal to a high-side switch and a low-side output signal to a low-side switch, respectively. The programming module includes a decoding unit configured to receive the enabling signal and the at least one input signal. The programming module further includes a preset unit coupled to the decoding unit. The decoding unit outputs decoded data to the preset unit, and the preset unit outputs a circuit parameter.

Abstract: A dynamic light control method for controlling at least one adjustable illumination parameter at a target location has been suggested. The method comprises setting the value of at least one adjustable illumination parameter at a first predetermined level, maintaining the value of the at least one adjustable illumination parameter at the first predetermined level for a first predetermined time period, varying the value of the at least one adjustable illumination parameter from the first predetermined level to a second predetermined level, maintaining the value of the at least one adjustable illumination parameter at the second level for a second predetermined time period, and varying the value of the at least one adjustable illumination parameter from the second level to a third predetermined level, wherein the varying the at least one adjustable illumination parameter comprises monotonously varying the at least one adjustable illumination parameter with a predefined maximum variation rate.

Abstract: A lighting experimental system and a lighting experimental method for reducing the ability of the poultry to recognize the red objects are provided, wherein wooden testing box is provided with an opening at the top thereof, a square adjustable light-emitting diode (LED) light source is disposed directly above the opening of the wooden testing box, a first black backdrop is fixedly laid on a surface of each inner wall of four sides of the wooden testing box, a horizontal trough is provided at the bottom of the wooden testing box, a feed box is disposed in the horizontal trough, and the feed box is connected to an electric push rod; two color photographic papers are fixed on an inner wall, directly above the horizontal trough, of the wooden testing box, pressure sensors are disposed between the color photographic papers and the inner wall of the wooden testing box.

Abstract: An in-wall power adapter is described. The in-wall power adapter comprises a first contact element configured to receive power; an outlet coupled to receive power from the first contact element; and a recess having contact elements adapted to provide at least one of power signals and control signals; wherein the recess is adapted to receive a module.

Abstract: An optoelectronic component includes an optoelectronic semiconductor chip that generates primary radiation during intended operation of the semiconductor chip, which primary radiation is coupled out via an emission side of the semiconductor chip, an optical element on the emission side and including a plurality of transmission fields arranged laterally side by side, wherein each transmission field is individually and independently electrically controllable, the transmission fields each include an electrochromic material, the transmission fields are such that, by electrically driving a transmission field, the transmittance of the electrochromic material for a radiation coming from the direction of the semiconductor chip during operation is changed and transmittance of the optical element in the region of the respective transmission field is changed for the respective radiation.

Abstract: A display device and a driving method, comprising: a time sequence controller generating a time sequence control verification signal on the basis of a display data signal; a high-speed interface of the time sequence controller transmitting the display data signal to a driver, and a low-speed interface of the time sequence controller transmitting a time sequence control verification signal to the driver; the driver generating a source driving verification signal on the basis of the display data signal; the driver comparing the source driving verification signal to the time sequence control verification signal; and on the basis of the comparison result, the driver triggering the time sequence controller to adjust the display data signal.

Abstract: To achieve visibility improvement and reduction of sense of incongruity in a vehicular lamp using LEDs. A lighting control device for controlling the on/off of a light source having a first and a second lamp unit each with LEDs including: a control part that generates a control signal for controlling the emitted lights of the lamp units; and a light source drive part for driving the lamp units based on the control signal; where the light emitted from the two lamp units driven by the light source driving part is such that each luminous intensity decreases from a first value to a second value which is smaller than the first value within a common period, and each luminous intensity decreases to the second value during the common period maintaining the relationship that the luminous intensity of the first lamp unit is lower than that of the second lamp unit.

Abstract: Articles of clothing include modules for sensing physical and/or physiological characteristics associated with use of the clothing or for performing other functions. Such clothing systems and methods may use physical or other interaction(s) between the module and the article of clothing for activating and/or deactivating the module and/or sensing devices included with the module, for example, to confirm whether the module and clothing are authorized for use with one another, and/or for automatic data algorithm selection methods. Additionally, such systems and methods also may sense interactions between the module and a module securing element of the clothing to determine characteristics associated with the clothing.

Abstract: An LED control system is provided for connection to an LED lighting system via a power line to control the LED lighting system using commands formed by manipulation of frequency and amplitude of a signal transmitted over the power line. The signal may be for example a wave or a sequence of pulses. The signal may be provided in superposition with line power or the line power may be formed as the signal.

Abstract: This application relates an activity detector (100) for detecting signal activity in an input audio signal (SIN), such as may be used for always-on speech detection. The activity detector has a first time-encoding modulator (TEM) 101 including a first hysteretic comparator (201) for generating a PWM (pulse-width modulation) signal based on the input audio signal. A second TEM (103) having a second hysteretic comparator (401) is arranged to receive a reference voltage (VMID) and generate a clock signal (SCLK). A time-decoding converter (102) receives the clock signal and generates count values of a number of cycles of the clock signal in periods defined by the PWM signal. An activity monitor (104) is responsive to a count signal (SCT) from the TDC 102 to determine whether the input audio signal comprises signal activity above a defined threshold.

Abstract: Disclosures of the present invention describe a human body-friendly light source constituted by at least one lighting unit and a plurality of color temperature (CT) reducing films stacked to each other. The CT reducing films are connected to a light emission surface of the lighting unit, so as to apply a color temperature reducing treatment to a light emitted from the lighting unit. Exponential data have proved that, two or more stacked CT reducing films exhibit an apparent color temperature reducing effect on the light. Exponential data have proved that, with the increasing of the stack numbers of the CT reducing films, the light is concerted to an orange-white light with color temperature in a range of 1,000-2,500 K, so as to make a sensitivity of melatonin suppression in response to the light be getting lower.

Abstract: A backlight driving device including a light source array, a driving circuit and a scanning circuit is provided. The light source array includes backlight units electrically connected to scanning lines and driving lines. The driving circuit outputs driving signals to the backlight units through the driving lines, and the driving signals respectively includes driving pulses in different time intervals. The scanning circuit outputs scanning signals to the backlight units through the scanning lines, and the scanning signals respectively includes a start pulse in at least one of the time intervals. The start pulses of the scanning signals respectively correspond to the driving pulses in the same time interval, and drive the backlight units of the each row of the light source array in time-division.

Abstract: An LED-based light includes one or more LEDs, a sensor arranged to detect a brightness level in an area resulting from the combination of light emitted by the LEDs with light from at least one ambient light source other than the LEDs, and operable to output a signal corresponding to the detected brightness level, a controller operable to regulate an amount of power provided to the LEDs in response to the signal, a light transmitting housing for the LEDs, the sensor and the controller and a connector shaped for connection with a light socket disposed at an end of the housing.

Abstract: Provided are a quantum dot light emitting diode and a manufacturing method. The quantum dot light emitting diode comprises: a pair of electrodes, arranged side by side and spaced; a flip chip light emitting diode, disposed on the electrodes and electrically connected to the electrodes; a quantum dot interlayer, disposed on the flip chip light emitting diode; a package layer, covering the electrodes, the flip chip light emitting diode and the quantum dot interlayer; and a whitening adhesive layer, surrounding the package layer. The quantum dot interlayer is disposed to isolate the invasion of the external water and oxygen to the quantum dot layer and the light emitting diode chip to form an environment, in which the quantum dots are isolated from water and oxygen.

Abstract: A system and method involving lighting fixtures, a control network, a controller and other devices such as light sensors, input devices and network adapters for coordinating precise brightness and color schedules among the lighting fixtures while maintaining a high color reliability including provisions for managing a plurality of lighting fixtures. The lighting fixtures contain lighting elements selected such that when controlled properly, operating along a daytime locus, the resultant light output closely resembles sunlight on a cloudless day in spectral characteristics, and wherein the total flux of blue light can be adjusted from a relative level of 1-100% the maximum blue flux of the lighting fixture by controlling individual lighting elements.

Abstract: A quantum dot LED and a manufacturing method for the same are disclosed. The quantum dot LED includes a pair of electrodes disposed separately and side by side; an LED chip disposed on the pair of electrodes and electrically connected to the pair of electrodes; a quantum dot layer disposed on the LED chip; a glue layer disposed on the quantum dot layer; and an inorganic encapsulation layer that packages and covers the pair of electrodes, the LED chip, the quantum dot layer and the glue layer. The present invention can provide a water and oxygen isolation environment, which is beneficial to increase the luminous efficiency and life of the quantum dots. Adopting an atomic layer deposition method to form the inorganic encapsulation layer, the surface is smooth and even in thickness, the problem of cracking of the film layer will not generate.

Abstract: A lighting control device that controls a lighting device includes: a brightness sensor that obtains brightness information indicating a current brightness of an illuminated surface; a storage that stores a brightness target value for the illuminated surface; a controller; a receiver via which the controller receives an energy-saving signal; and a transmitter that transmits, to the lighting device, a control signal generated by the controller. When the energy-saving signal is not being received, the controller determines a dimming rate for the lighting device based on the brightness target value and the brightness information. When the energy-saving signal is being received, the controller determines an energy-saving brightness target value smaller than the brightness target value by multiplying the brightness target value by a predetermined rate and determines an energy-saving dimming rate for the lighting device based on the energy-saving brightness target value and the brightness information.

Abstract: A lighting device having a first configuration wherein a first light source is exposed and a second light source is covered and a second configuration wherein the first light source is exposed and the second light source is exposed. The light device is enclosed in a rigid enclosure securing the lighting device in the second configuration. A power source is electrically coupled to the lighting device to provide power to the first light source and the second light source. A switch is coupled to the power source and the first and second light sources. The switch is configured to permit propagation of power from the power source to the second light source when the lighting device is in the second configuration.

Abstract: A light therapy device is provided that emits both blue spectrum wavelength light and cyan spectrum wavelength light stimulate intrinsically photosensitive Retinal Ganglion Cell (ipRGC) receptors located in a human eye. The light therapy device may be attached or secured in an area of or directly to a consumer device, such as a computer, or laptop, etc., so that a user operating the consumer device may utilize the consumer device and the light therapy device at the same time. Further, settings of the light therapy device may be controlled utilizing an application that may be executing on a computing device.

Abstract: A semiconductor laser driving apparatus for driving a semiconductor laser serving as a light source for optical scanning, the semiconductor laser driving apparatus includes: first and second switching elements that are each capable of switching energization of the semiconductor laser ON/OFF; a first pulse generation unit that intermittently outputs first driving pulses to the first switching element in a first time slot; and a second pulse generation unit that outputs a second driving pulse to the second switching element in a second time slot different from the first time slot.

Abstract: The present invention proposes a method for operating a hearing device 1 which prevents battery leakage, especially in the case when the hearing device 1 is powered by a mercury-free battery 2. The method comprises monitoring a supply voltage of at least one of a plurality of electronic units 7, 8, 9 of the hearing device 1, initiating a low battery leakage shutdown state when a low supply voltage condition is identified based on the monitoring, wherein the initiating a low battery leakage shutdown state includes activating at least one power gate 10 to disconnect at least one of the plurality of electronic units 7, 8, 9 from the power supply when entering the low battery leakage shutdown state, and discharging a buffer capacitor 4 provided for stabilizing the battery voltage. Moreover, a hearing device 1 optimized for being powered by a mercury-free battery 2 is provided.

Abstract: A light-emitting device includes an autotransformer, a circuit module and a light-emitting module. The autotransformer includes a first positive conductive wire for receiving a first input voltage within a first predetermined voltage range, a second positive conductive wire for receiving a second input voltage within a second predetermined voltage range, and a common negative conductive wire electrically mated to the first positive conductive wire and the second positive conductive wire. The first predetermined voltage range is larger than the second predetermined voltage range. The circuit module includes a driver electrically connected to the autotransformer, and a predetermined operating voltage value for driving the driver is substantially within the second predetermined voltage range. The light-emitting module is electrically connected to the driver.

Abstract: Provided is a sensor system for an outdoor lighting system including at least one sensor physically connected with an external connector of a lighting fixture of the outdoor lighting system. The sensor performs sensing and wireless data and power connection, via a wireless power source and a wireless data source, with the outdoor lighting system.

Abstract: In one embodiment, an igniter circuit may include a circuit to determine if the current through a load switch exceeds a threshold value, and to responsively disable a second switch that couples DC power to the igniter circuit.

Abstract: A system and method involving lighting fixtures, a control network, a controller and other devices such as light sensors, input devices and network adapters for coordinating precise brightness and color schedules among the lighting fixtures while maintaining a high color reliability including provisions for managing a plurality of lighting fixtures. The lighting fixtures contain lighting elements selected such that when controlled properly, operating along a daytime locus, the resultant light output closely resembles sunlight on a cloudless day in spectral characteristics, and wherein the total flux of blue light can be adjusted from a relative level of 1-100% the maximum blue flux of the lighting fixture by controlling individual lighting elements.

Abstract: In an illumination apparatus, a control unit starts lighting of a light source at a first time before a wake-up set time and executes a first control pattern to increase a dimming ratio of the light source from the first time to a second time determined based on the wake-up set time and a second control pattern to further increase the dimming ratio of the light source from the second time to a third time determined based on the wake-up set time. When a change curve of the dimming ratio in the first control pattern and the second control pattern is applied to a function represented by the equation: Y(t)=d+(a?d)/(1+(t/c)b), the time c becomes closer to the second time than the first time in the first control pattern, and becomes closer to the second time than the third time in the second control pattern.

Abstract: A lighting controller comprising a control module is disclosed. The control module transmits electrical current to various sets of lights in accordance with scheduling data for each set of lights. The scheduling data may include start data and stop data for each set of lights.

Abstract: A light bulb assembly comprises an electrical connection module, a driver circuit configured to provide electrical energy at a drive voltage, and a light source. The driver circuit converts electrical energy at an input voltage to the electrical energy at the drive voltage. A controller is configured to control the power converter to provide electrical energy at the drive voltage. The controller stops operation at an interruption of electrical energy to the driver circuit. The controller is configured to resume operation subsequent restoration of electrical energy to the driver circuit. The controller is configured to maintain the timing voltage above a first voltage level when the controller is in operation and to determine the duration of an interruption of electrical energy to the driver circuit.

Abstract: Lighting control systems, control modules for contactors, and methods of operating a lighting control system are described. In one example, a control module for a lighting contactor includes a controller, a power supply, and a control mode selector. The controller is configured to control operation of a lighting contactor in response to at least one control signal. The controller is selectively operable in a plurality of control modes. The power supply is configured to receive the at least one control signal and provide power to the controller. The control mode selector is coupled to the controller and operable to operate the controller in a selected control mode of the plurality of control modes.

Abstract: A scanning projector includes a brightness compensation component. The brightness compensation component modifies pixel brightness as a function of instantaneous scan phase of a sinusoidally scanning mirror. The brightness compensation component uses different brightness compensation functions based on whether the instantaneous scan phase is above or below a threshold. The threshold may correspond to a knee of a maximum laser power limit curve.

Abstract: This invention relates to an auto configuring runway lighting system. The auto configuring runway lighting system comprises a plurality of lighting apparatus. Each lighting apparatus comprises a means for determining geographic location information of the lighting apparatus. A central controller communicates with the plurality of lighting apparatus to obtain the geographic location information and controls the status of the plurality of lighting apparatus based on the geographic location information.

Abstract: A system and methods for automatically setting light intensity for covert operations are presented. Infra-red light is transmitted from at least one infra-red light source, and external ambient light is sensed substantially continually from at least one ambient light sensor coupled to a vehicle exterior to provide sensed ambient light. A sensed intensity of the sensed ambient light is compared to a sensitivity of a night vision goggles to provide a power adjustment value. An intensity level of the at least one infra-red light is controlled based on the power adjustment value such that the external ambient light is provided at a substantially optimal light level for the night vision goggles.

Abstract: In order to control of dimming of solid state lighting devices (SSL) a driver circuit drives the SSL subject to an input voltage using a phase-cut dimmer. The driver circuit comprises a transistor operable in two modes, either alternating between on/off states or continuously controlling a current through the transistor. A power converter network provides a switched-mode power converter in conjunction with the transistor when operated in the first mode generating a drive voltage for the SSL. The control unit controls the transistor to selectively operate in one of the two modes; to control the transistor to determine that the input voltage exceeds an input voltage threshold; and to control a drive current through the SSL based on a measurement of a phase-cut angle thereby controlling an illumination level of the SSL device.

Abstract: A single magnetic storage element is used to provide power to multiple lighting devices, which may be strings of light-emitting diodes (LEDs) of different color. A switching circuit controls alternating application of energy among the multiple lighting devices and another switching circuit may charge the primary winding to different energy levels to control the intensity of the multiple lighting devices. In particular, the multiple lighting devices may be controlled to provide a desired color profile while dimming the lighting devices, while requiring only a single magnetic storage element for supplying energy to the lighting devices.

Abstract: A scanning laser projector drives laser light sources with waveforms for higher efficiency. Optical light power values for pixels are mapped to amplitude/duration pairs. Laser diodes are driven with electrical currents having the amplitude for time period specified by the duration. For increasing optical light power values, amplitude values are increased, and then durations are increased.

Abstract: A pulse width modulation control unit multiplies a value of a user side setting signal by a value of a dimming signal to obtain a pulse width modulation output current control signal. The pulse width modulation control unit sends the pulse width modulation output current control signal to a light emitting diode driving unit. The light emitting diode driving unit multiplies a value of the pulse width modulation output current control signal by a value of a maximum output current of the light emitting diode driving unit to obtain a light emitting diode pulse width modulation driving current. The light emitting diode driving unit drives a light emitting diode by the light emitting diode pulse width modulation driving current.

Abstract: An LED module includes a light-emitting unit composed of a plurality of LEDs connected in series to one another, a sensor unit, a power interrupt circuit inserted into a power supply path through which the light-emitting unit is supplied with power from an external power source, and a control circuit that controls the power interrupt circuit according to output of the sensor unit. The LED module further includes a secondary battery and a voltage supply circuit. The voltage supply circuit supplies the control circuit with voltage equivalent to voltage drop between the ends of a group of LEDs included in the plurality of LEDs that constitute the light-emitting unit while the external power source is supplying power to the light-emitting unit, and supplies the control circuit with voltage output from the secondary battery while power interrupt circuit is interrupting the power from the external power source to the light-emitting unit.

Abstract: Embodiments relate to controlling a lighting control according to at least one of received signal strength indication (RSSI) and a preset lighting mode. Brightness or/and color temperature of the lighting device may be automatically controlled to two or more levels according to the RSSI and a user's taste. A switch application of the lighting device using the RSSI is operated to facilitate a control by a user, and On/Off or/and brightness of the lighting device are controlled according to the RSSI.

Abstract: The invention relates to a method for operation of an actively clocked PFC circuit with a directly or indirectly connected load circuit at the output of the PFC circuit, wherein the load circuit has a lighting means, in particular one or more LEDs, wherein the PFC circuit is supplied at least with a measurement signal which reflects the power consumption of the load circuit or with an external control signal which indicates the power consumption, and a control circuit adjusts the mode of operation of the PFC circuit continuously or preferably in two or more steps, depending on the control signal or measurement signal.

Abstract: From a start of a lighting until a predetermined time period passes, a high-pressure discharge lamp is supplied with a constant current (Ib) until the lamp power reaches a predetermined wattage (Plow). When the lamp power reaches the wattage (Plow), current is supplied to maintain the lamp power at the wattage (Plow). After another predetermined time period passes, current is supplied to maintain the lamp power at a rated lamp wattage (Pr). While this lamp power is being maintained, the size of the lamp current is limited to a current limit (Ia). The current (Ib) and the wattage (Plow) satisfy a relationship Ia·0.7?Ib?Ia·0.9 and Pr·0.5 Plow?Pr·0.9 to accelerate an initial building of luminous flux while reducing drainage to the electrodes.

Abstract: A switching current regulator controls a load current flowing through a load. The switching current regulator switches a switch to an ON state after applying a regulating signal to the switch. During an integration period while the switch is in the ON state, the switching current regulator integrates an output voltage based on a sense voltage based on the load current and a reference voltage; at the end of the integration period, the switching current regulator outputs an integrated output voltage. The switching current regulator compares the integrated output voltage to a predetermined value. Based on a result of comparing the integrated output voltage and the predetermined value, the switching current regulator adjusts the regulating signal.

Abstract: A power distribution system includes controller of a switching power converter to control the switching power converter and determine one or more switching power converter control parameters. In at least one embodiment, the switching power converter utilizes a transformer to transfer energy from a primary-side of the transformer to a secondary-side of the transformer. In at least one embodiment, the switching power converter control parameters includes a secondary-side conduction time delay that represents a time delay between when the primary-side ceases conducting a primary-side current and the secondary-side begins to conduct a secondary-side current. In at least one embodiment, determining and accounting for this secondary-side conduction time delay increases the prediction accuracy of the secondary-side current value and accurate delivery of energy to a load when the controller does not directly sense the secondary-side current provided to the load.

Abstract: An independently functioning or centrally controlled wall light switch is configured to operate in normal mode and a Jewish holiday mode wherein the state of the light is fixed, regardless of the user's physical manipulation of the light switch. The control system automatically activates holiday mode by combining a geographically determined Jewish religious clock executed by software and hardware that utilizes the current time, date and geographical location of the apparatus in accordance with the Jewish definition of time and laws for calculating numerous religiously significant shifting daily points in time. The control system further incorporates several energy saving and preference modes by utilizing a particular day's calculated religious points in time in conjunction with holiday behavior patterns common to most Jewish families to provide the user with a greatly simplified means of programming an automatically adjusting on/off light timer and dimming overlay functionality during holiday mode.

Abstract: A programmable light timer for implementing a timing pattern is described. The programmable light timer comprises a memory storing a plurality of timing patterns, each timing pattern being associated with a unique timing pattern code and having one or more on/off settings for a time period; and a user interface enabling the selection of a timing pattern code associated with a timing pattern of the plurality of timing patterns.

Abstract: A method of illuminating livestock with artificial light sources. The method includes generating a first light having a first light output that provides white light at typical lumen levels for workers. Then by using a dimming device the light source can be dimmed to provide a blue light at under 3 lumen in order to provide artificial light to the diurnal avians representative of moonlight to cause the occurrence of a predetermined characteristic visual spectral response of the diurnal avian substantially enclosed habitat for diurnal avians.

Abstract: A system for generating light with reduced physioneural compression. The system includes a first light source operable to emit light within a first wavelength range corresponding to a first photoreceptor and a second light source operable to emit light within a second wavelength range corresponding to a second photoreceptor. The system includes a controller functionally coupled to each of the first light source and the second light source. The controller is configured to alternately operate one of the first light source and the second light source with a duty cycle that is less than a response time of the visual cortex, but greater than a response time of physioneural cells, optionally including a latency between operation of light sources. The system may further include a third light source corresponding to a third photoreceptor.

Abstract: An LED (Light Emitting Device) light source (100), a pulse controller or pulse control module (130) for an LED light source, and a method are provided, for controlling relative timing and phase of LED light pulse generation and operation of peripheral devices, relative to a common timing reference. A system is provided comprising a pulse controller (130) for controlling synchronization of multiple LEDs (144) and/or other devices and peripherals (164), relative to a common timing reference. The pulse controller (130) comprises a processor (131) that programmatically executes a time based sequence of digital control signals (141) from received inputs (121) indicative of a pulse generation sequence.

Abstract: A power supply circuit (4) is responsive to an activating signal by supplying a discharge lamp (2) with an operating voltage on which a high voltage is temporality superposed. An insufficient current detecting circuit (46) detects abnormality of an output current supplied to the discharge lamp (2) from the power supply circuit (4). A CPU (52) stops the operation of the power supply circuit (4) in response to detection of abnormality by the insufficient current detecting circuit (46). An output nullification time period timer (50) nullifies the output of the insufficient current detecting circuit (46) for a predetermined time period measured from the supplying of the activating signal.

Abstract: Various apparatuses and methods for starting a thyristor are disclosed herein. For example, some embodiments provide an apparatus for controlling power to a load. The apparatus includes a thyristor, a secondary load switchably connected to an output of the thyristor, and a sensor connected to the secondary load. The sensor is adapted to connect the secondary load to the thyristor when the output of the thyristor falls below a predetermined level.