Speaker Mute Switch Circuit for Power-On Pop Noise Elimination
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Solution Overview
Problem
Conventional pop noise eliminators using a parallel architecture of transistors cannot completely eliminate pop noises when turning on an audio output device due to residual bias voltage, resulting in incomplete suppression of the pulse.
Innovation Solution
A pop noise eliminating circuit comprising a power source, grounding terminal, speaker, audio amplifier, delay unit, and two power control switches (NMOS transistors) that initially keeps the audio output loop in an open circuit status until the power source stabilizes, preventing pop noise production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If transistors are activated before starting up power supply to eliminate pop noises, then the voltage of the pulse is lowered, but the transistors still have bias voltage about 0V-0.2V which cannot completely eliminate the pulse
Solution Approach 1:
The patent extracts and removes the harmful pulse signal from the audio output loop by opening the circuit switch during power startup. Instead of merely lowering the pulse voltage through transistor biasing, the invention completely disconnects the audio amplifier from the speaker, preventing the unstable power supply pulse from reaching the output device.
Solution Approach 2:
The patent applies preliminary action by controlling the circuit switch to open before power supply stabilization and close after power supply becomes stable. This timing-based control prevents pop noise by ensuring the audio output loop is disconnected during the unstable power startup phase, addressing the root cause before it can produce harmful effects.
2Object-affected harmful factors
If the audio output loop is kept open during power startup to prevent pop noise, then pop noises are eliminated, but the device cannot output sound until power stabilizes
Solution Approach 1:
The patent uses periodic action by controlling the circuit switch to change states based on power supply stability. The switch opens during the unstable startup phase and closes when power stabilizes, creating a time-based control pattern that eliminates pop noise while minimizing sound output delay. This periodic switching ensures the system operates safely during startup while恢复正常功能 when conditions permit.
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 eliminates pop noises by maintaining the speaker in an off state during power instability, ensuring no sound output until the power source is stable, thus completely eliminating pop noise occurrences.
Implementation Method 1
a delay unit, which has one end electrically connected with the power source, a first power control switch, which has a control end electrically connected with the delay unit
Data Source
AI summary
An pop noise eliminating circuit includes a power source, a grounding terminal, a speaker, an audio amplifier that has two opposite ends respectively connected with the power source and the first end of the speaker, a delay unit that has one end electrically connected with the power source, a first power control switch that has a control end electrically connected with the delay unit, a first conduction end electrically connected with the other end of the speaker, and a second power control switch that has a control end electrically connected with the delay unit, a first conduction end electrically connected with the grounding terminal, and a second conduction end electrically connected with a second conduction end of the first power control switch.