Personal Projects

Microphone Amplifier Filter

Amplifies a very small signal such as that typically supplied from a sensor coil (magnetic field detector or a microphone) with Broken Coil Detection

  • If the coil is intact, then both the plus and minus inputs (Coil+ and Coil-) will be equal to that voltage and will cancel out in the differential op-amp circuit. Thus, only the signal differential generated by the coil will be amplified in this system.

Detects if the coil or the connecting wiring breaks

Band pass (a high pass and a low pass stage)

  • Low Pass filter: 3 poles and has a gain of 2. -3dB at 2.9 KHz

Final output of the circuit: high gain with mainly low pass filtering (Stages 1 to 5)

  • High pass filter: -3dB at 3.4 Hz