Abstract: A circuit includes a monitoring circuit that monitors a voltage and a switching circuit. Closing the switching circuit causes an external AC load to receive power from an external AC source. The circuit further includes a control circuit that opens the switching circuit for a time interval, where the time interval begins after the voltage is below a lower threshold. The control circuit also ends the time interval after the voltage exceeds an upper threshold, where the time interval is short enough that the operation of the AC load is not affected during the time interval. The circuit also includes a power harvesting circuit that harvests power from the external AC source to raise the voltage during the time interval.

Abstract: A thermostat includes a plurality of HVAC (heating, ventilation, and air conditioning) wire connectors for receiving a plurality of HVAC control wires corresponding to an HVAC system. The thermostat also includes a thermostat processing and control circuit operative to at least partially control the operation of the HVAC system and a powering circuit coupled to the HVAC wire connectors and configured to provide an electrical load power to the thermostat processing and control circuit. The thermostat includes circuitry and methods for maximizing efficiency of energy harvested from the HVAC system connected to the thermostat, and depending on which system is connected to the thermostat, different power schemes can be implemented in order to obtain power from the HVAC system.

Abstract: A thermostat includes a plurality of HVAC (heating, ventilation, and air conditioning) wire connectors for receiving a plurality of HVAC control wires corresponding to an HVAC system. The thermostat also includes a thermostat processing and control circuit operative to at least partially control the operation of the HVAC system and a powering circuit coupled to the HVAC wire connectors and configured to provide an electrical load power to the thermostat processing and control circuit. The thermostat includes circuitry and methods for maximizing efficiency of energy harvested from the HVAC system connected to the thermostat, and depending on which system is connected to the thermostat, different power schemes can be implemented in order to obtain power from the HVAC system.

Abstract: A dynamic power control circuit is provided. The control circuit can detect the presence of the external power source as well as detect one or more conditions of the device. For instance, the control circuit can detect a voltage difference between a first node coupling a first power output and a system circuit and a second node coupling a second power output and the batteries. The control circuit can also detect the activation or deactivation of the external power source. Based on the inputs, the control circuit can cause the controlled resistor to dynamically adjust a level of impedance between the first node and the second node. The controlled impedance between the first node and the second node enables the system circuit to dynamically utilize power supplied by the external power source as well as power supplied by the batteries.

Abstract: Latency-based selections of energy storage devices are described herein. In implementations, latency behavior of computing tasks performed by a computing device is predicted for a period of time. Based on the predicted latency behavior of the computing device over the period of time, an assessment is made regarding which of multiple heterogeneous energy storage devices are most appropriate to service the system workload. For example, high energy density devices may be favored for latency sensitive tasks whereas high energy density devices may be favored when latency sensitivity is not a concern. A combination of energy storage devices to service the current workload is selected based upon the latency considerations and then power supply settings are adjusted to cause supply of power from the selected combination of energy storage devices during the time period.

Abstract: Techniques for providing an enhanced resonant circuit amplifier are described herein. Using a capacitor to couple the drive to the resonant circuit can be problematic because the current flows the same direction with every energy burst, which causes the coupling capacitor to charge up and stop injecting energy into the resonant circuit. To solve this issue, embodiments disclosed herein add a burst of energy once every half cycle. This reduces distortion in the resonant energy. A second benefit is the ability to “push in” and “pull out” energy from the resonant circuit, which can prevent the capacitor from charging up and allow a resonant circuit amplifier to continually produce a symmetric, stable output. In addition, a controller can dynamically modify a number of aspects of an output, e.g., an amplitude and/or a DC bias, by modifying the duty cycle of an input signal.

Abstract: A thermostat is described that includes a rechargeable battery, a graphical user interface and a wireless network communication capabilities. During installation, in cases where the rechargeable battery is below a first threshold, the installation procedure is limited so as to avoid energy intensive installation steps which may not be supported by the low battery level. An example of an installation step that is avoided due to low battery level is set up of wireless communication. According to some embodiments, if the battery level is very low during initial installation, the installation process is halted while the battery is charged. An indication such as a flashing LED may be displayed so as to indicate to the user that the battery is being charged.

Abstract: An enhanced parallel protection circuit is provided. A system using separate battery packs in a parallel configuration is arranged with multiple protection circuit modules (PCMs). The PCMs are configured to detect fault conditions, such as over voltage, under voltage, excess current, excess heat, etc. Individual PCMs can be configured to control associated switches and/or other components. When a fault condition is detected by an individual PCM, the individual PCM triggers one or more associated switches to shut down one or more components. In addition, by the use of the techniques disclosed herein, the individual PCM can also trigger switches that are controlled by other PCMs. Configurations disclosed herein mitigate occurrences where a multi-PCM device is operating after at least one PCM has shut down. Configurations disclosed herein provide safeguards and redundant protection in scenarios where a fault event is detected by one PCM and not detected by another PCM in a parallel configuration.

Abstract: Schedule-based energy storage device selection is described for a device having an energy storage device system with heterogeneous energy storage devices, such as heterogeneous battery cells. The techniques discussed herein use information regarding a user's schedule (e.g., the user's calendar) to predict future workload patterns for a computing device and reserve energy storage device capacities across multiple heterogeneous energy storage devices to improve efficiency of the energy storage devices. For example, if a user is expected to attend a video conference call later in the day (e.g., due to the video conference call being on the user's calendar), then energy in an energy storage device that is better capable of handling such a workload (providing power during the video conference call) more efficiently is preserved so that the energy is available when the video conference call occurs.

Abstract: A circuit includes a monitoring circuit that monitors a voltage and a switching circuit. Closing the switching circuit causes an external AC load to receive power from an external AC source. The circuit further includes a control circuit that opens the switching circuit for a time interval, where the time interval begins after the voltage is below a lower threshold. The control circuit also ends the time interval after the voltage exceeds an upper threshold, where the time interval is short enough that the operation of the AC load is not affected during the time interval. The circuit also includes a power harvesting circuit that harvests power from the external AC source to raise the voltage during the time interval.

Abstract: Techniques for providing an enhanced resonant circuit amplifier are described herein. Using a capacitor to couple the drive to the resonant circuit can be problematic because the current flows the same direction with every energy burst, which causes the coupling capacitor to charge up and stop injecting energy into the resonant circuit. To solve this issue, embodiments disclosed herein add a burst of energy once every half cycle. This reduces distortion in the resonant energy. A second benefit is the ability to “push in” and “pull out” energy from the resonant circuit, which can prevent the capacitor from charging up and allow a resonant circuit amplifier to continually produce a symmetric, stable output. In addition, a controller can dynamically modify a number of aspects of an output, e.g., an amplitude and/or a DC bias, by modifying the duty cycle of an input signal.

Abstract: A large-power insulated gate switching device (e.g., MOSFET) is used for driving relatively large surges of pulsed power through a load. The switching device has a relatively large gate capacitance which is difficult to quickly discharge. A gate charging and discharging circuit is provided having a bipolar junction transistor (BJT) configured to apply a charging voltage to charge the gate of the switching device where the BJT is configured to also discontinue the application of the charging voltage. An inductive circuit having an inductor is also provided.

Abstract: Latency-based selections of energy storage devices are described herein. In implementations, latency behavior of computing tasks performed by a computing device is predicted for a period of time. Based on the predicted latency behavior of the computing device over the period of time, an assessment is made regarding which of multiple heterogeneous energy storage devices are most appropriate to service the system workload. For example, high energy density devices may be favored for latency sensitive tasks whereas high energy density devices may be favored when latency sensitivity is not a concern. A combination of energy storage devices to service the current workload is selected based upon the latency considerations and then power supply settings are adjusted to cause supply of power from the selected combination of energy storage devices during the time period.

Abstract: A thermostat is configured for automated compatibility with HVAC systems that are either single-HVAC-transformer systems or dual-HVAC-transformer systems. The compatibility is automated in that a manual jumper installation is not required for adaptation to either single-HVAC-transformer systems or dual-HVAC-transformer systems. The thermostat has a plurality of HVAC wire connectors including a first call relay wire connector, a first power return wire connector, a second call relay wire connector, and a second power return wire connector. The thermostat is configured such that if the first and second external wires have been inserted into the first and second power return wire connectors, respectively, then the first and second power return wire connectors are electrically isolated from each other. Otherwise, the first and second power return wire connectors are electrically connected.

Abstract: A large-power insulated gate switching device (e.g., MOSFET) is used for driving relatively large surges of pulsed power through a load. The switching device has a relatively large gate capacitance which is difficult to quickly discharge. A gate charging and discharging circuit is provided having a bipolar junction transistor (BJT) configured to apply a charging voltage to charge the gate of the switching device where the BJT is configured to also discontinue the application of the charging voltage. An inductive circuit having an inductor is also provided.

Abstract: A large-power insulated gate switching device (e.g., MOSFET) is used for driving relatively large surges of pulsed power through a load. The switching device has a relatively large gate capacitance which is difficult to quickly discharge. A gate charging and discharging circuit is provided having a bipolar junction transistor (BJT) configured to apply a charging voltage to charge the gate of the switching device where the BJT is configured to also discontinue the application of the charging voltage. An inductive circuit having an inductor is also provided.

Abstract: A dynamic power control circuit is provided. The control circuit can detect the presence of the external power source as well as detect one or more conditions of the device. For instance, the control circuit can detect a voltage difference between a first node coupling a first power output and a system circuit and a second node coupling a second power output and the batteries. The control circuit can also detect the activation or deactivation of the external power source. Based on the inputs, the control circuit can cause the controlled resistor to dynamically adjust a level of impedance between the first node and the second node. The controlled impedance between the first node and the second node enables the system circuit to dynamically utilize power supplied by the external power source as well as power supplied by the batteries.

Abstract: A thermostat for controlling an HVAC system in an enclosure may include a passive infrared sensor, an active infrared sensor, and an electronic display having a first mode and a second mode. The thermostat may also include one or more processors programmed to change a setpoint temperature of the thermostat to an energy-saving temperature upon detection of a non-occupancy condition for the enclosure. The processor(s) may detect the non-occupancy condition based at least in part on readings received from the passive infrared sensor. The processor(s) may also be programmed to change the electronic display from the first mode to the second mode upon detection of a person approaching the thermostat. The processor(s) may detect a person approaching the thermostat based at least in part on readings received from the active infrared sensor.

Abstract: An enhanced parallel protection circuit is provided. A system using separate battery packs in a parallel configuration is arranged with multiple protection circuit modules (PCMs). The PCMs are configured to detect fault conditions, such as over voltage, under voltage, excess current, excess heat, etc. Individual PCMs can be configured to control associated switches and/or other components. When a fault condition is detected by an individual PCM, the individual PCM triggers one or more associated switches to shut down one or more components. In addition, by the use of the techniques disclosed herein, the individual PCM can also trigger switches that are controlled by other PCMs. Configurations disclosed herein mitigate occurrences where a multi-PCM device is operating after at least one PCM has shut down. Configurations disclosed herein provide safeguards and redundant protection in scenarios where a fault event is detected by one PCM and not detected by another PCM in a parallel configuration.

Abstract: A thermostat and related methods are described for controlling one or more functions, such as heating and cooling in an HVAC. According to some embodiments the thermostat includes a switching circuit for controlling an HVAC function, where closing the switching circuit activates the HVAC function. The thermostat may also include power harvesting circuitry adapted and arranged to harvest power from the HVAC system, where during times when the HVAC function is active the switching circuit opens for a time interval. The power harvesting circuitry may harvest power from the HVAC system during the time interval, and the time interval may be short enough that the HVAC function remains activated without interruption during the time interval.