Convert a spealer to a microphone circuit

Convert A Speaker To A Microphone Circuit

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Speaker to microphone circuit analysis
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Convert a speaker to a microphone with this circuit
An 8 Ohm Loudspeaker can be used as a Microphone in this speaker to microphone circuit.

Notice that a load of down to 500 Ohms can be used to produce a clean 2.18 mV RMS signal output with only a single stage. The 8 Ohm Resistor is removed and a speaker inserted