Open Circuit Current Limiter for Portable Multimeters
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Solution Overview
Problem
Portable electrical multimeters consume significant battery life when left in low-ohms measurement mode with an open-circuit configuration, as they continue to draw current from the battery power source without actively measuring resistance.
Innovation Solution
A resistance measurement circuit with a current control component that reduces current flow during open-circuit configurations by controlling the gate bias of a field-effect transistor (FET) and using a thermistor to manage power consumption, ensuring minimal current draw when not actively measuring resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the multimeter continues to draw current from the battery power source during open-circuit configuration, then the measurement function remains ready for use, but the battery life is significantly decreased
Solution Approach 1:
The patent implements dynamic current control by detecting the circuit configuration state (open-circuit vs. closed-circuit) and adjusting the current draw accordingly. The current control component dynamically switches between high current (for active measurement) and low current (for idle state), resolving the contradiction between maintaining readiness and conserving battery life.
Solution Approach 2:
The patent changes the operating parameter (current draw) based on the measurement state. By detecting whether the circuit is open or closed, the system adjusts the current parameter to match the actual need, thereby reducing unnecessary power consumption while maintaining measurement capability when needed.
2Use of energy by moving object
If the multimeter draws minimal current during idle states, then battery life is extended, but the current control complexity increases
Solution Approach 1:
The patent employs a self-regulating current control mechanism that automatically detects the circuit state and adjusts current draw without external intervention. The detection circuit and current control component work together to autonomously manage power consumption, reducing the need for complex user-controlled switching mechanisms.
Solution Approach 2:
The patent implements a feedback loop where the detection circuit monitors the circuit configuration and provides information to the current control component, which then adjusts the current draw accordingly. This feedback mechanism enables automatic adaptation to changing states, managing complexity through intelligent control rather than multiple discrete switches.
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
Significantly reduces battery power consumption by limiting current flow during idle states, thereby extending the battery life of portable multimeters.
Implementation Method 1
using a thermistor to manage power consumption
Data Source
AI summary
A resistance measuring circuit includes a current generating component, a current control component, and a voltage measurement component. The magnitude of a target resistance can be measured by connecting the target resistance between first and second measurement terminals of the resistance measuring circuit, applying a current generated by the current generating component to the target resistance, and determining the voltage across the target resistance. When no target resistance is connected between the first and second measurement terminals, the current control component controls the current generating component to reduce current consumption of the resistance measuring circuit.