Electronic Inductance Circuit for 2-Wire Intercom Power Supply
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Solution Overview
Problem
Conventional electronic inductance circuits for 2-wire video intercom systems face challenges in providing sufficient direct current power supply while maintaining stable alternating current impedance, particularly at low frequencies like 300Hz, due to limitations in resistor values and impedance, which restrict the size and efficiency of the intercom system.
Innovation Solution
The proposed electronic inductance circuit includes a main circuit path with an inductor and FET, a resistor, and a freewheeling diode connected in parallel, along with a secondary circuit path through a capacitor and another resistor, allowing for a coil inductor with an auxiliary resistor and freewheeling diode as alternating current feedback components, enabling larger direct current power supply with stable alternating current impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coil inductor is used as the inductance component, then the audio signal impedance is sufficient, but the size of the inductor becomes very large
Solution Approach 1:
The patent replaces the traditional mechanical coil inductor with an electronic inductance circuit comprising a FET, capacitor, and resistor. This substitution eliminates the need for large magnetic components while achieving the required inductance effect through electronic components, thereby reducing size while maintaining audio signal impedance.
Solution Approach 2:
The patent changes the operating parameters of the FET (gate-source voltage, drain current) to dynamically control the equivalent inductance. By adjusting these parameters, the circuit achieves the required inductance value without requiring large physical components, thus resolving the contradiction between impedance sufficiency and size reduction.
2Volume of moving object
If an electronic inductance circuit with alternating current feedback resistor is used, then the size is reduced, but the direct current power supply capability and alternating current impedance are limited
Solution Approach 1:
The patent introduces dynamic control of the FET gate-source voltage that adapts to the load current requirements. The circuit dynamically adjusts the FET operating point based on the required power supply capability, enabling the compact electronic circuit to provide sufficient direct current power supply capability while maintaining reduced size.
Solution Approach 2:
The patent implements feedback mechanisms where the drain current is sensed and used to adjust the gate-source voltage of the FET. This feedback loop enables the circuit to automatically regulate the power supply capability according to load demands, overcoming the limitation of fixed-parameter electronic inductance circuits.
3Reliability
If the resistor value is increased to improve alternating current impedance, then the impedance is sufficient, but the voltage drop increases and power consumption increases
Solution Approach 1:
The patent uses a relatively small resistor value combined with the dynamic FET control to achieve the required alternating current impedance. Instead of relying on a large resistor, the circuit uses the FET's variable resistance characteristic controlled by gate voltage, achieving sufficient impedance with minimal power dissipation.
Solution Approach 2:
The patent changes the FET's operating parameters (gate-source voltage) to dynamically adjust its on-resistance. This allows the circuit to achieve high alternating current impedance when needed while maintaining low power consumption during normal operation, resolving the contradiction between impedance and power loss.
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 configuration allows for a larger direct current power supply with stable alternating current impedance that does not change with direct current variations, enhancing the performance and size capabilities of 2-wire intercom systems.
Implementation Method 1
a main circuit path along an inductor and a source terminal and a drain terminal of a FET between the input terminal and the output terminal of the electronic inductance circuit
Implementation Method 2
a secondary circuit path along a capacitor connected with a second resistor in series between the input terminal and the output terminal
Implementation Method 3
a main circuit path along an inductor and a source terminal and a drain terminal of a FET
Data Source
Figure 1~2
Figure 3~4
AI summary
An electronic inductance circuit for the power supply of a 2-wire bus intercom system and a device thereof. The electronic inductance circuit comprises a main circuit path along an inductor (LI) and the source terminal (S) and the drain terminal (D) of a FET (Ql) between the input terminal (Al) and the output terminal (AO) of said electronic inductance circuit, in which said inductor is connected to said source terminal of said FET; a resistor (Rl) and a freewheeling diode (Dl) individually connected to said inductor in parallel; and a secondary circuit path along a capacitor (CI) connected with a second resistor (R2) in series between said input terminal and said output terminal, which is connected to said main circuit path in parallel. The solutions of the electronic inductance circuit achieve larger direct current power supply for the 2-wire intercom system and stable alternating current impedance with fast response to the DC power supply.