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1. 09:48 AM - Re: Headset repair (Robert L. Nuckolls, III)
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| Subject: | Re: 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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