Electrical

The microphone used is a Panasonic Electret Condenser (model number WM-034CY195M).

The circuit is based around the given biasing circuit, with a small low-pass filter on the output.  

The signal amplitude is typically very small, so in order to be detected by the ADC of the Mega163 a negative feedback amplifier with large gain is used.  

Two channels were constructed for left and right microphones. The outputs of these circuits go to ADC0 and ADC7 respectively. A capacitor is inserted across the rail voltages to try and reduce the amount of noise, and all the other ADC channels are grounded for this reason as well.

Schematic

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Last modified: May 01, 2002