Output Transformer Amplifier Circuit for Back-EMF Suppression
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Solution Overview
Problem
Conventional amplifier devices suffer from back-EMF voltage generation, which distorts sound quality by causing voltage displacement at the ground point and affects multiple devices connected to a common power supply, with existing solutions only correcting the output voltage without suppressing the back-EMF voltage itself.
Innovation Solution
Incorporating a back-EMF voltage suppression circuit with a diode and capacitor in parallel between the power supply and constant potential terminals, short-circuiting the back-EMF current regardless of its polarity, thereby eliminating the back-EMF voltage and minimizing its influence on the output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a voice coil vibrates in a magnetic field to drive the speaker, then sound waves are produced, but back-EMF voltage is generated that flows back to the amplifier and distorts the voice signal
Solution Approach 1:
The harmful back-EMF voltage is extracted and diverted from the main signal path by providing a separate discharge path through the capacitor connected between the power supply terminal and ground, allowing the back-EMF energy to be discharged independently without affecting the voice signal
Solution Approach 2:
The back-EMF voltage, which is normally harmful, is converted into a beneficial effect by using it to charge the capacitor, which then can discharge this energy in a controlled manner through the capacitor to ground, preventing the harmful feedback while utilizing the generated energy
2Device complexity
If the back-EMF voltage is allowed to flow back through the amplifier circuit, then the circuit remains simple, but voltage displacement occurs at the ground point causing potential distortion
Solution Approach 1:
A capacitor is introduced as an intermediary element between the power supply terminal and ground, serving as a dedicated path for back-EMF discharge that isolates the ground reference from voltage fluctuations caused by back-EMF, thereby maintaining ground potential stability without complicating the overall circuit architecture
3Adaptability or versatility
If multiple amplifier devices share a common AC power supply, then resource utilization is efficient, but back-EMF voltage from one device affects other devices connected to the same power supply
Solution Approach 1:
The common power supply system is segmented into isolated units by providing each amplifier device with its own capacitor connected to its power supply terminal, creating independent back-EMF discharge paths that prevent the propagation of back-EMF voltage between devices while maintaining efficient power supply sharing
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 approach effectively suppresses back-EMF voltage generation, ensuring faithful and noiseless sound waves are produced, improving sound quality by preventing distortion and voltage fluctuations.
Implementation Method 1
a back-EMF voltage suppression circuit interposed between the power supply terminal and the constant potential terminal and provided with a diode and a capacitor arranged in parallel
Implementation Method 2
the voltage (current) generated by the power generation is generally called a back-EMF voltage (back-EMF current)
Data Source
AI summary
An amplifier device includes a back-EMF voltage shorting circuit between a power supply terminal located on a primary side of an output transformer and a constant potential terminal grounded. The back-EMF voltage shorting circuit is provided with a capacitor and a diode in parallel. When a back-EMF voltage input into a circuit of an amplifier device is a positive potential, a back-EMF current flows from the power supply terminal toward the constant potential terminal, and the back-EMF current is short-circuited by the capacitor at this time. On the other hand, when the input back-EMF voltage is a negative potential, the back-EMF current flows from the constant potential terminal toward the power supply terminal, and is short-circuited by the diode at this time.