Abstract: The present document describes systems and techniques of a battery heater failsafe circuit in a video-capturing doorbell. In aspects, the battery heater failsafe circuit is configured to monitor a temperature of one or more regions proximate or adjacent to a battery. If, while under software control of a processing unit, a battery heater is activated and, due to a software malfunction, the battery approaches or is equal to an upper threshold temperature, then the battery heater failsafe circuit can override the software-control of the battery heater to disconnect the battery heater from the processing unit and/or the battery. When, as a result, the temperature of the battery equals or drops below a lower threshold temperature, the battery heater failsafe circuit is capable of reconnecting the battery heater to the processing unit and/or the battery sufficient to enable a reactivation of the battery heater and allow heat generation.

Abstract: The subject matter described herein provides systems and techniques for controlling the production of eNoise in an audio playback system. The eNoise may be an audible noise produced when a current, such as a noise/ripple current, flows through a battery of the audio playback system. Such eNoise may be reduced by limiting the current, such as noise/ripple current, flowing through the battery. In some examples, the noise/ripple current may be diverted to the main board of the audio playback system by adding a source of current. A circuit to produce such a current may include transistor(s), capacitor(s), and/or resistor(s). Using the current source and/or such a circuit may also divert the noise/ripple current away from the battery, thereby reducing the eNoise produced.

Abstract: The present disclosure describes a system and method for protecting an electronic device from high voltages that may exceed tolerance limits for circuitry within the electronic device. A protection circuit blocks high voltages from the device components through gating techniques. Such gating techniques may similarly be used to control whether power is received by the electronic components when an error condition is detected by a control unit.

Abstract: The subject matter described herein provides systems and techniques for controlling the production of eNoise in an audio playback system. The eNoise may be an audible noise produced when a current, such as a noise/ripple current, flows through a battery of the audio playback system. Such eNoise may be reduced by limiting the current, such as noise/ripple current, flowing through the battery. In some examples, the noise/ripple current may be diverted to the main board of the audio playback system by adding a source of current. A circuit to produce such a current may include transistor(s), capacitor(s), and/or resistor(s). Using the current source and/or such a circuit may also divert the noise/ripple current away from the battery, thereby reducing the eNoise produced.