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                           AeroElectric-List Digest Archive
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                     Total Messages Posted Tue 03/24/20: 1
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Today's Message Index:
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     1. 09:48 AM - Re: Headset repair  (Robert L. Nuckolls, III)
 
 
 
________________________________  Message 1  _____________________________________


Time: 09:48:24 AM PST US
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Subject: Re: AeroElectric-List: Headset repair

At 07:12 PM 3/23/2020, you wrote:
>Busting open the mic cartridge reveals this. The tiny mic component 
>has 55DK02 stamped on the side.  With o-scope leads across the 
>terminal, I'm not able to get any response by speaking into it.

    I'd bet that 99.999% of all microphone elements
    in common service are of the 'electret' variety.
    Easy to make, rugged, can be very small . . . but
    this comes with a price.

    Special attention needs to be paid to smooth
    frequency response and minimize distortion. Qualities
    of concern for 'high end' mic manufacturers (studio
    quality recordings). Many high-end microphones
    still exploit legacy technologies to achieve
    the desired performance.

    But the great unwashed, 'communications
    grade' microphones will use this technology.

https://tinyurl.com/k59r249

    These critters need to be biased at something
    on the order of 2-4 volts. In aircraft microphones,
    getting this bias is no big deal . . . aircraft
    audio systems EXPECT a carbon microphone analog,
    their design includes a bias network to supply
    voltage to the microphone.

    So your experiment to exercise the microphone
    while observing output on a 'scope would
    not yield useful information unless you
    implement the necessary external bias
    supply.


   Bob . . . 

 

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