Noise Cancelling Condenser Microphone

Noise Cancelling Condenser microphone is a great choice for noise-cancelling applications due to their small size, low power consumption, and high sensitivity. They work in conjunction with active noise cancellation circuitry to create a more peaceful listening experience.

Electret Condenser microphones (ECMs) can be very effective for noise cancellation when used correctly. Here’s why:

Small size: ECMs are naturally small, making them ideal for incorporating into headphones and headsets where space is limited.

Low power consumption: They require very little power to operate, which is important for battery-powered devices like noise-cancelling headphones.

High sensitivity: ECMs can pick up a wide range of sounds, including both your desired signal and background noise.

Most noise-cancelling headphones use two microphones. One faces outward to pick up ambient noise, while the other faces inward to pick up the sound reaching your ears

Here’s a simplified representation of the circuit:

This circuit is a dual-microphone noise-cancelling preamplifier that uses two 2N2222 transistor stages to isolate the speaker’s voice from ambient background noise.

The system operates on a 9V DC power supply and features two separate input paths for condenser microphones labeled MK1 and MK2. The first stage consists of Q1 and Q3 acting as high-gain amplifiers for their respective microphone inputs. A 20k potentiometer, marked as RP1, is integrated into the first stage to allow for precise gain balancing between the two paths, which is essential for effective phase cancellation.

The second stage uses Q2 and Q4 as output drivers to strengthen the signal before it reaches the final output. The fundamental principle of this design is subtractive cancellation, where common background noise picked up by both microphones is phased out, leaving only the desired audio at the AF output header. All coupling and decoupling are handled by 47µF electrolytic capacitors to ensure stable DC biasing while allowing the AC audio signal to pass through the stages.

Download Gerber files here – Noise Cancelling Condenser Microphone

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