Hi Nigel

Yes I have tried it. It just works with a dynamic microphone but I get
nothing from an electret microphone.

Steve

-----Original Message-----
From: Nigel Orr <nigel.orr@NCL.AC.UK>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Thursday, February 04, 1999 8:05 AM
Subject: Re: [OT] electret microphone preamp


>At 11:08 03/02/99 +1100, you wrote:
>>using an op-amp or just a transistor would be fine. The input impedance of
>>the ISD33000 analog input is 3k and it takes a maximum of 32 mV p-p when
fed
>>in single ended input mode.
>
>I may have totally misread this, but...
>
>A typical simple mic preamp would have a voltage gain of about 40dB (x100),
>with an output voltage of about 1Vrms, so the mic signal is probably a
>nominal 10mV rms, or 30mV pk-pk.  That would suggest that the analog input
>on your new chip _is_ already a mic input.  Have you tried it?
>
>Nigel
>--
>Nigel Orr                  Research Associate   O   ______
>        Underwater Acoustics Group,              o / o    \_/(
>Dept of Electrical and Electronic Engineering     (_   <   _ (
>     University of Newcastle Upon Tyne             \______/ \(
>