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Message ID: 6651     Entry time: Sun May 20 19:57:51 2012
Author: Den 
Type: Update 
Category: PEM 
Subject: microphones 

I've soldered EM172 microphones to BNC connectors to get data from them.

DSC_4287.JPG    DSC_4285.JPG

Then I've build an amplifier for them. The circuit is


I've build 6 such circuits inside 1 box. It needs +15 V to A3 and GND to A2. A1 power channel is not used.

DSC_4284.JPG     DSC_4286.JPG

LISO model for this scheme was created and simulation results were compared to measurement of each channel

freq_resp.png   noise.png

Measured noise curve (green) is the SR785 own noise.

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