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microphone circuit

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fromansr

New Member
Does anyone know how to get an electret microphone to output a 32mVp-p
voice signal, with a 3V supply? Also what sort of scope waveform should I be getting from it?



ps. the mic output will be going into an ISD4002 chip.

Thanks.
 

audioguru

Well-Known Member
Most Helpful Member
The electret mic produces about 25mv p-p when it is powered from a 10k resistor from 9V, has a load of 47k ohms or more, from a person talking in a normal speaking voice level about 14cm away from the electret mic.

Your application should have the mic powered from a 3.3k resistor from a filtered source of 3V and have a load of 16k ohms or more. But the input impedance of the ISD4002 is only 3k ohms which will reduce the output from the mic. Then if the person raises their voice level a fair amount then it will produce the 32mv p-p that you need.

the 'scope waveform will be a microphone signal.
 
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