Condenser microphones are everywhere, especially in the age of the internet and voice control. They are used in a wide range of devices, from karaoke microphones to high-end wireless microphones, high-quality voice recorders, and various Bluetooth speakers. Even AI toys use condenser microphones. Here is a detailed explanation of how they work and what they are made of:
Table of Contents
The Basic Concept of Capacitance
Capacitance is created by two conductors that are close to each other but not connected. In theory, any two conductors form a capacitor. For example, two wires twisted together can create a capacitance of about 4-6 picofarads (pF). Understanding this concept is crucial for using condenser microphones.
Structure of a Condenser Microphone
Diaphragm: The diaphragm in a condenser microphone is a thin membrane that needs to be coated with a thin layer of metal. This is one of the conductors (one plate of the capacitor).
Backplate: The backplate is also a metal-coated membrane, forming the other conductor (the other plate of the capacitor).
Insulating Spacer: Placed between the diaphragm and the backplate, the spacer creates a gap, allowing the diaphragm to vibrate and ensuring the two conductors do not touch.
How It Works
A condenser microphone needs a voltage to work, which creates an electric charge between the diaphragm and the backplate. When sound waves hit the diaphragm, it vibrates and changes the distance between it and the backplate. This change in distance alters the capacitance, converting the sound waves into an electrical signal.
The Role of Electret Materials
In the late 1960s and early 1970s, the discovery of electret materials solved the problem of constantly needing to apply a voltage to the condenser microphone. Electret materials can hold a charge for a long time after being exposed to a high voltage. By coating the diaphragm with a metal layer and using electret materials, the electret condenser microphone was born.
Amplifying the Signal
The electrical signal from a condenser microphone is very weak. To make it usable, it needs to be amplified. Field-effect transistors (FETs) are commonly used to amplify the signal. This makes the output signal strong enough for practical use.
Key Components of a Condenser Microphone
A condenser microphone mainly consists of four parts:
- Diaphragme
- Entretoise isolante
- Backplate
- FET Amplifier
Usage Considerations
Condenser microphones need a working voltage to function, unlike dynamic microphones, which generate electrical signals through the movement of a coil in a magnetic field. Modern condenser microphones typically require a working voltage of 2-3 volts, with a maximum of 6 volts and an extreme limit of 9 volts.
Conclusion
Condenser microphones are used in various devices, including remote controls and voice-controlled gadgets. Understanding their basic concepts and how they work can help you better apply and troubleshoot them.