Abstract: A power supply system includes at least two power supply devices that supply a current to a load. Each of the at least two power supply devices includes a converter configured to generate a current that is to be supplied to the load, an FET that is connected in series between the converter and the load, a gate voltage monitoring circuit configured to monitor whether a gate voltage of the FET has fallen below a predetermined first reference voltage, and an alarm generation circuit configured to generate an alarm according to a result of monitoring by the gate voltage monitoring circuit.

Abstract: A microgrid control system that can govern power provided to a load from various power sources. The microgrid control system can determine apportionment of power between the various sources based on characteristic power features of the various sources.

Abstract: In various embodiments, a control system for an electronic circuit iteratively applies voltage to and senses current from a load to regulate operation of the load.

Abstract: An apparatus includes a thermistor having a variable resistance with a first dependence on absolute temperature. The apparatus includes a reference resistor having a resistance with a second dependence on absolute temperature, the second dependence being less than or having opposite polarity to the first dependence. The reference resistor includes a switched-capacitor circuit. The apparatus includes a node coupled between the thermistor and the reference resistor. The node is configured to provide a signal indicative of absolute temperature based on the variable resistance and the reference resistance. The signal may be strain-invariant, proportional to a reference voltage, and indicative of a ratio of the variable resistance to the reference resistance. The apparatus may include a feedback circuit configured to maintain the node at a predetermined voltage level.

Abstract: In a power converter, a circuit determines an average value of an inaccessible current from an average value of an accessible current and a value of the operating duty cycle of the converter. A method of measuring an average value of an inaccessible current from a measured value of a current, in a power converter, by a duty cycle of a pulse width modulation (PWM) signal, representing a duty cycle of the power converter. Coupling a voltage representing the measured value to an input of a low pass filter during a time period (D) and coupling the input of the low pass filter to a reference voltage during a time period (1?D).

Abstract: The present disclosure is directed to a protection system for a wind turbine power system connected to a power grid. The protection system includes a main brake circuit having at least one brake resistive element and at least one brake switch element, a battery system, and a controller. The brake resistive element is coupled to at least one of a DC link of a power converter of the wind turbine power system, windings of a rotor of the generator, or windings of a stator of a generator of the wind turbine power system via the brake switch element. The battery system is coupled to the generator via a battery switch element. In addition, the controller is configured to disconnect the power converter and the generator from the power grid and connect at least one of the main brake circuit or the battery system to the generator in response to detecting an electromagnetic (EM) torque loss event so as to generate an EM torque.

Abstract: The present invention relates to methods for controlling a multi-channel power supply and to corresponding devices. According to one embodiment of the invention, a method for controlling a multi-channel power supply is provided. Therein each channel comprises an intrinsic channel resistance and a resistor adjustable between a lowest resistance and a highest resistance. The method comprises the following steps: Measuring for each channel a measure indicative of a current in the respective channel; Adjusting, on the basis of the measures, the adjustable resistor in the channel having the highest intrinsic channel resistance to the lowest resistance; and Adjusting, on the basis of the measures, the adjustable resistor(s) in the remaining channel(s), such that currents in each channel are balanced. With it a concept of simultaneously performing current balancing and reduction of power dissipation is provided.

Abstract: A respective electronically controlled switch is provided in series with the output of each PD. A control circuit having a timer functionality is further provided, with the electronically controlled switches responsive to the control circuit. Upon detection that a second PD, defined temporally, is provided with operating power, the respective electronically controlled switch is maintained open for a predetermined hold-off time period sufficient to ensure detection by the respective PD control state machine of the completion of startup. After expiration of the predetermined hold-off time period, the respective electronically controlled switch is closed thus enabling normal operation.

Abstract: In accordance with embodiments of the present disclosure, a power supply unit may comprise a plurality of output terminals configured to supply electrical energy to one or more information handling resources, a measurement module configured to measure one or more parameters indicative of an intermediate impedance between the power supply unit and at least one other power supply unit, and a microcontroller unit. The microcontroller unit may be configured to estimate an intermediate impedance based on the one or more parameters and communicate the intermediate impedance to a controller of an information handling system in which the power supply unit is disposed.

Abstract: A wireless power receiver that receives wireless power from a wireless power transmitter and a control method thereof are provided, wherein the wireless power receiver receives the wireless power from the wireless power transmitter; rectifies the wireless power; monitoring a voltage value of the rectified wireless power; determines whether a ripple of the voltage value of the wireless power is greater than or equal to a preset threshold; and if the ripple of the voltage value of the wireless power is greater than or equal to the preset threshold, changes at least one element value of the wireless power receiver to suppress the ripple below the preset threshold.

Abstract: Methods, computing systems and computer program products implement embodiments of the present invention that include determining a required electrical power level for one or more computer elements. Upon selecting a first value indicating a first electrical power level that is less than the required electrical power level, the first value is conveyed to a first power supply unit (PSU), so that that the first PSU delivers, to the one or more computer elements, the first electrical power level. A second value is selected that indicates a second electrical power level that is different from the first value, the second value indicating a difference between the required electrical power level and the first electrical power level. The second value is conveyed to a second PSU, so that that upon receiving the second value, the second PSU delivers, to the one or more computer elements, the second electrical power level.

Abstract: This application relates to a lighting system comprising a plurality of light emitting diode, LED, circuits, and a power source for providing a drive voltage to the plurality of LED circuits. For each LED circuit, the lighting system comprises a first variable resistance element connected between the respective LED circuit and ground, and a first feedback circuit configured to control a voltage at a first node between the respective LED circuit and the respective first variable resistance element to a first voltage. The lighting system further comprises a current source and a second variable resistance element connected between the current source and ground, wherein each first variable resistance element is configured to attain a resistance value depending on a resistance value attained by the second variable resistance element.

Abstract: Technology is provided for distributed power delivery to a processing unit on a printed circuit board. In one example, a printed circuit board includes a processing unit coupled to multiple power channels, including first channels on a first side of the processing unit, and second channels on a second side of the processing unit. The printed circuit board further includes a first power supply coupled to the processing unit via the first channels, and a second power supply coupled to the processing unit via the second channels. The processing unit is configured to receive a total current, including currents drawn substantially simultaneously from the first power supply and the second power supply. The total current is about equivalent to a current the processing unit would draw from a single power supply.

Abstract: A vehicle is supplied by a first electrical energy storage unit on board the vehicle, and a ground electrical network providing an energy supply by application of a supply voltage through electrical distribution. The first energy storage unit is controllable under a generator regime or a receiver regime. The supply voltage is adjusted, in the generator regime, by applying an algebraically additive supply voltage originating from the first electrical storage unit to the distribution, to maintain a supply voltage above a minimum threshold. In the receiver regime, if a surplus of supply voltage originating at least partially from a second storage unit in the generator regime is detected above the minimum threshold, this surplus is channeled energetically to the first energy storage unit of the vehicle if it is required for operating the vehicle and enables maintaining the supply voltage below a maximum threshold and above the minimum threshold.

Abstract: The supercapacitor-based grid fault ride-through system provides a dynamic model of a wind generation system including a Voltage Source Converter (VSC), which functions as a Static Compensator (STATCOM). The power control capability of the STATCOM is extended by incorporating energy stored in a supercapacitor. The system implements a vector control technique based on the decoupling of real and reactive power. Simulation results show that a fixed speed induction generator is capable of withstanding a significant grid fault when aided by the supercapacitor-based grid fault ride-through system. Moreover, the induction generator regains its pre-fault status immediately after the fault is cleared.

Abstract: A power supply system includes a plurality of power supply units that each includes an output terminal connected each other in parallel to other output terminals each included in other power supply units and connected to a plurality of load units, a power supply section that inputs an input voltage and outputs a first output voltage from the output terminal to the plurality of load units, and a shut-off control section that shuts off the output of the first output voltage from the output terminal based on an inputted stand-by signal, and a management control unit that inputs a configuration information representing a configuration of each of the plurality of load units in which the first voltage is inputted, and outputs the stand-by signal to any of the plurality of power supply units based on the configuration information.

Abstract: A controller is disclosed for hybrid systems providing power to an electrical power grid. The controller reduces wear on hybrid systems by having only a fast unit tuned to track fluctuations of a regulation signal in a normal mode of operation. By contrast, the slow unit does not track fluctuations in the regulation signal in the normal mode of operation, which reduces wear on the slow unit. The normal mode of operation is defined by an energy range of the fast unit. Energy band parameters associated with the energy range can be dynamically modified in order to optimize the efficiency of the hybrid system.

Abstract: Certain embodiments of the disclosure may include systems, methods and apparatus for providing a gate driver circuit for an alternative energy power supply. According to an example embodiment of the disclosure, a gate drive circuit for an alternative energy power supply may be provided. The gate drive circuit may include one or more switching device units operated in parallel. The gate driver circuit is configured to selectively control the multiple the switching devices in order to balance currents between each of the parallel-connected switching devices.

Abstract: A system for controlling the operation of isolation transistors in high power Power over Ethernet (PoE) networks to achieve greater power delivery to a load is disclosed. In one or more implementations, the system includes a first power over Ethernet (PoE) powered device controller configured to control power supply to a load, and a second PoE powered device controller coupled to the load and to the first PoE powered device controller. The second PoE powered device controller is connected to the first PoE powered device controller using a shared connection interface and is configured to control power supply to the load. The shared connection interface is configured to synchronize the first PoE powered device controller and the second PoE powered device controller to deliver power at least substantially contemporaneously to the load.

Abstract: A lamp base having an electrical device recharging receptacle configured to receive a plug from a recharging device for a portable rechargeable electronic device. The receptacle is configured as a standard automobile cigarette lighter receptacle. The receptacle includes standard cigarette lighter receptacle electrical contacts that are connected to a voltage and current conversion circuit for receiving standard household voltage and converting it into standard automotive voltage and current. An adapter receptacle is provided in the lamp base with securable replacement electrical and mechanical connection mechanism, wherein the conversion circuit provides a voltage and current to the adapter receptacle. A replaceably securable USB adapter plug comprising a second conversion circuit for converting the voltage and current provided to the adapter receptacle into a standard USB voltage and current.

Abstract: A control unit of a system stabilization device uses a fluctuation detection block (60) to determine fluctuation components included in the active component and reactive component currents of a system current and fluctuation components included in the frequency signal and the amplitude signal of a system voltage. The high frequency cut-off of the fluctuation detection block (60) is set to be f1; the low frequency cut-off is set to be f2. The fluctuation detection block (60) is composed of a low-pass filter (61) with a time constant of T1, a low-pass filter (62) with a time constant of T2, a subtracter (63) which outputs the difference, between the output signals of the filter (61) and the filter (62), and a feedback circuit (64) which provides feedback on the output of the subtracter (63) to the filters (61, 62). Thus, stability is ensured without using a current detector.

Abstract: A constant current circuit includes a first transistor, a second transistor having the gate and the source connected to the gate and the source of the first transistor, and having the drain connected to a load, a voltage adjustment circuit section that controls the drain voltage of the first transistor, a constant current generation circuit section that supplies a constant current to the first transistor, and a detection circuit section that determines whether at least one of the first transistor and the second transistor is unable to output a current proportional to the first constant current while at least one of the first transistor and the second transistor operates in the linear region, by performing a voltage comparison between a voltage at a connecting section between the voltage adjustment circuit section and the constant current generation circuit section and a predetermined reference voltage.

Abstract: In the case where the rotation speeds of respective magneto alternating current (AC) generators of a plurality of power source apparatuses (10, 20, and 30) are approximately the same rotation speed and the total electric power generation demand is the same as or smaller than the maximum total generated electric power of the plurality of power source apparatuses (10, 20, and 30), the integrated control unit (6) for integrally controlling the plurality of power source apparatuses (10, 20, and 30) selects at least one of the plurality of the power source apparatuses (10, 20, and 30) and controls a voltage control unit (5) of the selected power source apparatus in such a way that the selected power source apparatus generates maximum generated electric power thereof, at the rotation speed, that is the same as or smaller than the total electric power generation demand.

Abstract: A transfer system may be provided. The transfer system may comprise a first transfer switch comprising first normally closed contacts and first normally open contacts. In addition, the transfer system may comprise a second transfer switch comprising second normally closed contacts and second normally open contacts. Furthermore, the transfer system may comprise third normally closed contacts with a solid state switch in parallel. A source monitor may be configured to monitor the quality of a primary source and a backup source. And a source control may be configured to operate the first transfer switch, the second transfer switch, the third normally closed contacts, and the solid state switch to transfer a load from the primary source to the backup source in response to the monitored quality of the primary source and the backup source.

Abstract: The supercapacitor-based grid fault ride-through system provides a dynamic model of a wind generation system including a Voltage Source Converter (VSC), which functions as a Static Compensator (STATCOM). The power control capability of the STATCOM is extended by incorporating energy stored in a supercapacitor. The system implements a vector control technique based on the decoupling of real and reactive power. Simulation results show that a fixed speed induction generator is capable of withstanding a significant grid fault when aided by the supercapacitor-based grid fault ride-through system. Moreover, the induction generator regains its pre-fault status immediately after the fault is cleared.

Abstract: A semiconductor IC device capable of power-sharing includes a first power line configured to be supplied with a first power, a second power line configured to be supplied with a second power, a switching block configured to connect the first power line with the second power line in response to a first control signal, and a power-sharing control block configured to generate the control signal in accordance with a plurality of operation command signals.

Abstract: The present disclosure provides a power supply system. The power supply system includes a plurality of power supply devices connected in parallel. Output terminals of the plurality of power supply devices are coupled to a common supply line. Each of the plurality of power supply devices includes a DC-to-DC converter, a transformer, a switching control device, a rectifying device, and a judging device. The judging device receives a feedback voltage, an error signal and a second AC voltage to determine whether the power supply device is normal, wherein the feedback voltage is a voltage division of an output voltage on the common supply line, the error signal is an output of the switching control device, and the second AC voltage is retrieved from a second winding set of the transformer.

Abstract: An outlet or multi-outlet power strip device for interrupting standby power is provided that includes at least one standby power shut-off unit, which is provided correspondingly to at least one receptacle outlet and either supplies or shuts off power to an electronic product connected to the at least one receptacle outlet depending on the status of the electronic product; an outlet power supply, which receives power from the at least one standby power shut-off unit, and converts and supplies the input power to the outlet; a mode selector, to which a selected mode on whether the outlet should be operated in independent mode or cooperative mode is input; and a controller, which sets a standby current of the electronic product, detects the power status of the electronic product by using the set standby current, and controls the at least one standby power shut-off unit according to the detected power status.

Abstract: A controller is disclosed for hybrid systems providing power to an electrical power grid. The controller reduces wear on hybrid systems by having only a fast unit tuned to track fluctuations of a regulation signal in a normal mode of operation. By contrast, the slow unit does not track fluctuations in the regulation signal in the normal mode of operation, which reduces wear on the slow unit. The normal mode of operation is defined by an energy range of the fast unit. Energy band parameters associated with the energy range can be dynamically modified in order to optimize the efficiency of the hybrid system.

Abstract: A control methodology for an engine-driven electric machine of a hybrid vehicle electrical system for enabling continued operation of the vehicle electrical system under failure mode conditions that require or result in disconnection of the battery pack from the electrical system. At the onset of a fault condition requiring battery disconnection, the electric machine is controlled to drive the battery pack current toward zero before disconnecting the battery pack. Once the battery pack is disconnected, whether by relay or fuse, the electric machine is controlled to maintain the bus voltage of the electrical system at a specified value. In both operating modes, the electric machine is controlled based on a synchronous vector current command that is determined directly as a function of the control objective (zero battery pack current or maintaining bus voltage) for improved response time compared to a traditional torque-based control.

Abstract: A turbo compounding system may include a turbo generator having a switched reluctance machine having at least one pole-matched rotor and stator pair, a single phase inverter coupled to the turbo generator and further coupled to a direct current link, an inverter coupled to the direct current link, a motor generator coupled to the inverter.

Abstract: A semiconductor module has switching semiconductor elements connected in parallel to each other and at least a free wheeling semiconductor element reversely connected in parallel to the switching semiconductor elements. The free wheeling semiconductor element is placed between the switching semiconductor elements. At both end parts of the semiconductor elements, each of the switching semiconductor elements is placed. A longitudinal side of each of the switching semiconductor elements and the free wheeling semiconductor element is placed in parallel to a short side of the semiconductor module. An electric-power conversion device has a plurality of arms. Each arm is composed of the semiconductor elements.

Abstract: A device for delivering a desired power to a load comprises a voltage detection module, a comparator module, a power regulation module, and a current source. The voltage detection module generates a voltage signal based on a voltage across the load. The comparator module compares a first value based on the voltage signal to a power reference signal. The power reference signal is based on the desired power. The power regulation module generates a digital code based on the comparison. The current source provides a current to the load. The current is based on a predetermined constant current and a second value. The second value is based on the digital code.

Abstract: A method of power point tracking for operating a photovoltaic power plant, which includes a DC-DC converter of the output voltage of a panel having a power switch driven by a PWM control signal of variable duty-cycle generated by a PWM control circuit, in discontinuous conduction mode or continuous conduction mode depending on the current load of the converter, is implemented by low cost analog circuits. The method does not require the use of any analog-to-digital conversion, digital processing or storage resources and may use a single voltage sensor.

Abstract: A current controller for a spacecraft comprises ripple regulators and a pulse width modulated regulator. Ripple regulators receive current from associated current sources and pass current to or shunts current away from the bus. The pulse width modulated regulator receives current from another current source and passes a portion of the current to the bus. This regulator varies its set point to float between ripple regulators passing current and the ripple regulators shunting current and adjusts a portion of current that is shunted away from the bus. The current shunted by the regulators form a total shunt current. The variable set point of the pulse width modulated regulator varies as the total shunt current varies. The ripple regulator set points do not vary in this manner. An error generation circuit generates an error that adjusts the ripple regulator and the pulse width modulated regulator to a desired bus voltage level.

Abstract: A lamp base having an electrical device recharging receptacle configured to receive a plug from a recharging device for a portable rechargeable electronic device. The receptacle is configured as a standard automobile cigarette lighter receptacle. The receptacle includes standard cigarette lighter receptacle electrical contacts that are connected to a voltage and current conversion circuit for receiving standard household voltage and converting it into standard automotive voltage and current.

Abstract: An integrated circuit is partitioned into two or more sub-circuits, each sub-circuit including two supply terminals across which to receive supply voltage. The sub-circuits are connected in series with the first sub-circuit receiving input voltage at its first supply terminal, and the voltage level output at the second supply terminal of the first sub-circuit being used as input voltage level in a second sub-circuit. Further, a control-circuit is configured to balance voltage drops across the sub-circuits and to maintain constant voltage-drops over the sub-circuits. The control-circuit includes two buffer capacitors, each coupled in parallel over one of the two sub-circuits respectively. The control-circuit also includes at least one bucket capacitor alternately coupled in parallel over the first and the second buffer capacitor through a switching system controlled by a toggling signal.

Abstract: In at least some embodiments, a system comprises a load and a fuel cell coupled to said load, the fuel cell being configured to provide a constant power level to said load. The system further comprises a battery coupled to said load and configured to provide power in excess of said constant power level to said load, if needed by said load.

Abstract: A current controller for a spacecraft comprises ripple regulators and a pulse width modulated regulator. Ripple regulators receive current from associated current sources and pass current to or shunts current away from the bus. The pulse width modulated regulator receives current from another current source and passes a portion of the current to the bus. This regulator varies its set point to float between ripple regulators passing current and the ripple regulators shunting current and adjusts a portion of current that is shunted away from the bus. The current shunted by the regulators form a total shunt current. The variable set point of the pulse width modulated regulator varies as the total shunt current varies. The ripple regulator set points do not vary in this manner. An error generation circuit generates an error that adjusts the ripple regulator and the pulse width modulated regulator to a desired bus voltage level.

Abstract: Techniques for DC-to-AC conversion are disclosed, and may be embodied in a solar inverter device that can operatively couple to a power grid. The device includes a photovoltaic (PV) stack including series-connected PV modules. Each PV module is associated with a capacitor for storing output of that PV module. A positive terminator circuit switches a negative end of the PV stack to ground during positive half of grid cycle, and a negative terminator switches a positive end of the PV stack to ground during negative half of grid cycle. A connecting branch couples each PV module output to a common bus, each branch including control circuitry configured to selectively couple the corresponding PV module output to bus. During a first half of grid cycle, some of the capacitors discharge to the grid while a balance of the capacitors charge in preparation for discharge during a second half of grid cycle.

Abstract: The solution controls electric operational power to be fed to an amplifier. The control can be carried out, for instance, in accordance with a predetermined signal. The operational power is fed to the amplifier with a voltage source unit and a current source unit, and the operational voltage that the voltage source unit feeds to the amplifier is controlled. The current source unit feeds at least some of the operational electric current of the amplifier.

Abstract: Procedures to prevent the disconnection of a park of electricity generators from a network in the event of a voltage sag, through which, upon detection of the sag, the voltage travelling to the network is controlled in proportion to the magnitude of the sag; the active power produced by the park, rather than sent to the network, is thus diverted into to storage and/or energy dissipation equipment, keeping the park voltage at a nominal level. The invention also includes a device for carrying out procedures integrating a bypass, transformer, static inverter, static converter, capacitance and dissipation resistance unit, voltage sag detection circuit and control circuit.

Abstract: A method and a device for non-contact energy transmission from one or more medium-frequency current sources, whose medium frequencies may have deviations around fM, to one or more moving consumers via one or more transmission lines and from or via transformer heads, allocated to the moving consumers, having one or more downstream matching controllers for adjusting the power received from the transmission lines. The currents fed into a matching controller are brought together with the aid of a single switch, depending upon the power demand of the consumers connected to the matching controller. The switching frequency of the switch is selected as a fixed value from a 10%-wide tolerance band around 1/fM. The output voltages of a plurality of matching controllers are able to be parallel-connected via diodes for supplying a consumer.

Abstract: A power supply and switching technique is provided that utilizes a first battery and a second battery to charge a load. The power supply includes a first controlled power switch coupled to the first battery and the load, a second controlled power switch coupled to the second battery and the load, and a power controller coupled to the first controlled power switch, the second controlled power switch and the load. The power controller monitors the voltage and the load and causes a charge to be applied to the load when the load voltage is not a predetermined voltage. The power controller causes a charge to be applied to the load by selectively closing the first controlled power switch, thereby providing a charge from the first battery to the load, and/or selectively closing the second controlled power switch, thereby providing a charge from the second battery to the load. A similar switching technique may be used to recharge the first and second battery by alternately coupling them to an external power source.

Abstract: A circuit for generating electric power at the moment a D.C. pulsating power is suspended includes an induction device in series with or in parallel with the load for generating the power and supplying it to the load.

Abstract: A power supply and switching technique is provided that utilizes a first battery and a second battery to charge a load. The power supply includes a first controlled power switch coupled to the first battery and the load, a second controlled power switch coupled to the second battery and the load, and a power controller coupled to the first controlled power switch, the second controlled power switch, and the load. The power controller monitors the voltage and the load and causes a charge to be applied to the load when the load voltage is not a predetermined voltage. The power controller causes a charge to be applied to the load by selectively closing the first controlled power switch, thereby providing a charge from the first battery to the load, and/or selectively closing the second controlled power switch, thereby providing a charge from the second battery to the load. A similar switching technique may be used to recharge the first and second battery by alternately coupling them to an external power source.

Abstract: A power supply and switching technique is provided that utilizes a first battery and a second battery to charge a load. The power supply includes a first controlled power switch coupled to the first battery and the load, a second controlled power switch coupled to the second battery and the load, and a power controller coupled to the first controlled power switch, the second controlled power switch, and the load. The power controller monitors the voltage and the load and causes a charge to be applied to the load when the load voltage is not a predetermined voltage. The power controller causes a charge to be applied to the load by selectively closing the first controlled power switch, thereby providing a charge from the first battery to the load, and/or selectively closing the second controlled power switch, thereby providing a charge from the second battery to the load. A similar switching technique may be used to recharge the first and second battery by alternately coupling them to an external power source.

Abstract: The process provides constant electric power from a combination of a wind energy generator and a firm secondary generator. The wind energy generator and the secondary generator supply electricity directly to a utility transmission system. The secondary generator must be able to provide power on demand that will meet a utility's needs. The secondary generator is preferably a natural gas turbine, but may be a hydrogen fuel cell, a diesel internal combustion engine, or any other similar technology.

Abstract: A current regulator that controls a load current by selectively connecting the load to a high voltage source and a low voltage source. The switching is triggered by a command pulse. By switching between the high voltage source and the low voltage source, the regulator controls load current without generating emissions. The low voltage source also maintains the load current at a selected level without requiring switching.

Abstract: A sensor circuit detects a current supplied to a set of light-emitting diodes and produces a current reading dependent on the temperature of .operation of these light-emitting diodes. The sensor circuit comprises first and second serially interconnected resistors also connected in series with the set of light-emitting diodes. The sensor circuit also comprises a temperature-dependent impedance connected in parallel with one of the first and second resistors. At least a portion of the current through the set of light-emitting diodes flows through the sensor circuit to enable the first and second serially interconnected resistors and the temperature-dependent impedance to produce a variable voltage signal representative of the current through the set of light-emitting diodes, this variable voltage signal being dependent upon temperature. The above sensor circuit finds application in a substantially constant intensity light source.