Doorbell Transistor Rectifier Assembly for Low-Voltage Power Conversion
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Solution Overview
Problem
Audio/video recording and communication doorbell devices experience significant power dissipation and voltage drop due to full-wave rectifier circuits, leading to insufficient power supply and increased costs or size, especially when powered from limited sources like photovoltaic devices or batteries.
Innovation Solution
Incorporating a transistor assembly that emulates a full-wave rectifier circuit, reducing power dissipation and allowing operation with lower input voltages, by using field effect transistors with lower forward voltage drops, and providing a DC path between input and output power buses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a full-wave rectifier circuit with diodes is used to convert AC input power to DC output power, then the doorbell device can be powered from AC electrical power sources, but significant power is dissipated due to diode forward voltage drops
Solution Approach 1:
The patent replaces diodes with transistors in the rectifier circuit, changing the key parameter from diode forward voltage drop (typically 0.6-0.7V) to transistor saturation voltage (typically 0.2-0.3V for BJTs or lower for MOSFETs). This parameter change reduces the voltage drop across the rectifier elements, thereby reducing power dissipation while maintaining the AC to DC conversion functionality. The transistor assembly can be configured as a bridge rectifier or other rectification topology, providing the same adaptability to AC power sources with improved energy efficiency.
2Power
If a full-wave rectifier circuit is used to convert AC input power to DC output power, then power conversion is achieved, but voltage drop across diodes results in insufficient power supply voltage when input voltage is small
Solution Approach 1:
The patent changes the voltage drop parameter by substituting diodes with transistors. Transistors exhibit lower voltage drops in their on-state compared to diodes, particularly MOSFETs which can have on-resistance values that result in minimal voltage drop at operating currents. This allows the rectifier circuit to maintain higher output voltage for a given input voltage, ensuring sufficient power supply voltage even when the input voltage is small or when powered from limited capacity sources like photovoltaic devices or batteries.
3Temperature
If cooling devices such as heatsinks are added to handle power dissipation, then thermal management is improved, but cost and size of the doorbell device increase
Solution Approach 1:
The patent converts the harmful effect of power dissipation into a benefit by using transistors that inherently dissipate less power. Instead of adding cooling devices to manage the heat generated by diode-based rectifiers, the invention eliminates the need for such cooling devices by choosing transistor components with lower power dissipation characteristics. This approach transforms the thermal management problem into a component selection opportunity, where the transistor's low voltage drop becomes a feature that reduces the need for thermal management hardware, thereby reducing device size and cost.
4Power
If a full-wave rectifier circuit is used, then AC to DC conversion is achieved, but the diode forward voltage drop causes significant power loss that may necessitate cooling devices
Solution Approach 1:
The patent applies parameter changes by substituting diodes with transistors in the power conversion circuitry. This component substitution changes the electrical parameters of the rectifier, specifically the voltage drop across the switching elements. Transistors, particularly MOSFETs operated in their linear or triode region, exhibit much lower on-state resistance compared to diode forward voltage drops. This parameter change reduces power loss during AC to DC conversion, eliminating or reducing the need for cooling devices and simplifying the overall device complexity while maintaining effective power conversion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The transistor assembly reduces power dissipation and voltage drop, enabling the doorbell devices to operate efficiently with lower input voltages and reducing the need for cooling devices, thus enhancing performance and reliability.
Implementation Method 1
the transistor assembly is configured to emulate a full-wave rectifier circuit, and/or to provide a DC path between an input power bus and an output power bus
Implementation Method 2
by using field effect transistors with lower forward voltage drops
Data Source
AI summary
An audio/video (A/V) recording and communication doorbell device includes a transistor assembly and control circuitry. The transistor assembly is electrically coupled between an input power bus that distributes alternating current (AC) input power and/or direct current (DC) input power, and an output power bus that provides a DC output power for the A/V recording and communication doorbell device. The control circuitry is configured to cause the transistor assembly to convert AC input power and/or DC input power from the input power bus to the DC output power into the output power bus, to provide the DC output power for the A/V recording and communication doorbell device.