Condenser Microphone Circuit for Wide Phantom Power Variation
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Solution Overview
Problem
Existing condenser microphone circuits using a two-line wiring system struggle to support variations in phantom power supply voltage, particularly between 11 V to 52 V, leading to signal distortion and reduced dynamic range.
Innovation Solution
A condenser microphone circuit design incorporating a constant current diode, collector grounding transistors, and voltage dividing resistors to stabilize operation across varying power supply voltages, allowing for a two-line wiring system that maintains signal quality and dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a two-line wiring system is used to reduce the number of lines, then the flexible pipe portion size is reduced, but the output signal becomes distorted more easily and dynamic range decreases
Solution Approach 1:
The patent introduces a constant current diode as an intermediary component between the power supply and the FET. This constant current diode stabilizes the current flow to the FET, preventing signal distortion and maintaining dynamic range while enabling the use of a two-line wiring system. The constant current diode acts as a mediator that decouples the power supply voltage variations from the FET operation, allowing reliable signal transmission through the reduced wiring configuration.
2Adaptability or versatility
If the phantom power supply voltage varies within 11 V to 52 V range, then the circuit must support wide voltage variation, but existing two-line wiring circuits cannot maintain stable operation
Solution Approach 1:
The patent employs parameter changes by introducing a constant current diode that converts voltage variations into a stable current parameter. The constant current diode maintains a fixed current flow regardless of the power supply voltage variations between 11 V and 52 V, thereby stabilizing the FET operation. Additionally, the voltage dividing resistors adjust the base potentials of the transistors to accommodate different voltage levels, enabling the circuit to adapt to wide voltage variations while maintaining stable operation.
Solution Approach 2:
The circuit implements dynamic adaptation through the voltage dividing resistors connected to the transistor bases. These resistors automatically adjust the base potentials according to the power supply voltage level, allowing the circuit to dynamically respond to voltage variations. The constant current diode also provides dynamic current stabilization, ensuring that the FET receives consistent current despite changes in power supply voltage, thus maintaining circuit stability across the 11 V to 52 V range.
3Reliability
If collector grounding transistors and voltage dividing resistors are added to stabilize operation, then circuit complexity increases, but signal distortion is reduced and dynamic range is enhanced
Solution Approach 1:
The patent applies the self-service principle through the constant current diode, which automatically regulates the current flow to the FET without requiring external control circuits. The voltage dividing resistors also provide self-adjusting base potentials based on the power supply voltage, eliminating the need for additional active stabilization components. This self-regulating approach improves signal quality and dynamic range while minimizing the increase in circuit complexity, as the added components operate autonomously to stabilize the circuit.
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 circuit effectively supports power supply voltage variations from 11 V to 52 V, reducing signal distortion and enhancing dynamic range, while maintaining a compact two-line wiring configuration.
Implementation Method 1
a constant current diode that supplies a current to the FET
Implementation Method 2
the second resistor divides voltage on a cathode side of the constant current diode
Implementation Method 3
a collector grounding second transistor that amplifies the output signal from the FET
Data Source
AI summary
Provided is a condenser microphone circuit that can support variation in power supply voltage of a phantom power supply using a wiring system of two lines. A condenser microphone circuit includes a microphone unit, an FET, a constant current diode, a collector grounding first transistor that generates an operation power supply of the FET, a first resistor that sets base potential of the first transistor, a collector grounding second transistor that amplifies an output signal from the FET, a second resistor that sets base potential of the second transistor, and an output circuit. A base of the first transistor is connected to a source of the FET, an emitter of the first transistor is connected to a drain of the FET, a base of the second transistor is connected to the drain of the FET, an emitter of the second transistor is connected to the output circuit, and the second resistor divides voltage on a cathode side of the constant current diode.