Decoder Constant Current Sink Circuit for Irrigation
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Solution Overview
Problem
Existing two-wire power and communication systems for irrigation systems are limited by sensitivity to power surges, require extensive and costly external surge protection, and face issues with voltage reduction affecting decoder communication, leading to false command recognition and size limitations.
Innovation Solution
The system employs a constant current sink circuit with a shunt regulator and internal surge protection within each decoder, allowing decoders to draw a consistent current despite voltage changes and reducing the need for external surge protection devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If decoders use fixed resistor circuits to switch to a circuit path with a resistor between the common current and ground, then the decoder can communicate with the central controller, but any reduction in voltage causes a proportional reduction in the current pulse, causing the gateway to not recognize the acknowledgment pulse and falsely determine that the decoder did not receive a command
Solution Approach 1:
The patent changes the electrical parameters of the decoder circuit by replacing fixed resistor circuits with voltage-regulated constant current circuits. This allows the current pulse to remain stable despite voltage variations in the two-wire system, ensuring reliable command recognition by the gateway controller.
2Length of moving object
If decoders are installed further away from the gateway or central controller, then the system can cover a larger area, but the resistance of the power and communication wires becomes significant and reduces the voltage available across the decoder
Solution Approach 1:
The patent implements voltage regulation and constant current sourcing at the decoder level, which compensates for voltage drops over long wire runs. This allows the system to extend to greater distances while maintaining reliable operation.
3Quantity of substance
If large numbers of decoders are installed in the system, then the system can control more sprinklers, but this further reduces voltage and increases resistance on the power and communication wires
Solution Approach 1:
The patent employs constant current sinking and voltage regulation at each decoder, which stabilizes the electrical parameters despite the addition of multiple decoders to the system. This allows for expansion to control large numbers of sprinklers without degrading system performance.
4Measurement precision
If decoder circuitry that listens for communications are sensitive to power surges by lightning, then the decoder can detect communication signals, but expensive, external surge devices with ground rods must be installed at short intervals along the power and communication wires
Solution Approach 1:
The patent integrates surge protection functionality directly into the decoder circuitry itself, allowing the decoder to protect its own communication and power circuitry without requiring external surge protection devices. This eliminates the need for expensive external surge protectors with ground rods.
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
This solution enhances system scalability, reduces installation costs, and minimizes surge-related damage by maintaining reliable communication and power delivery across longer distances with fewer external surge protection devices.
Implementation Method 1
decoders have a constant current sink circuit that includes a shunt regulator that controls a field effect transistor
Implementation Method 2
a constant current sink circuit that includes a shunt regulator that controls a field effect transistor
Data Source
AI summary
A two-wire power and communication system is provided, having a decoder that draws a constant amount of current for communication signals despite changes in the voltage on the power and communication wires. In one example, decoders have a constant current sink circuit that includes a shunt regulator that controls a field effect transistor.