Optical Microphone Schematic
1. IR LED is driven at DC (No modulation in this version)
2. A high-gain transimpedance amplifier converts the photocurrent to a voltage.
3. High-pass filter to strip out the DC component and get the audio only
4. Gain stage: non-inverting amplifier with 1/2 Vcc reference voltage
5. Another high-pass capacitor, to remove the DC reference voltage.
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