Johan,
at what frequency did you measure.
I have measured a significant C (up to some nF) in parallel to R at the input
of some soundcards.
73, Rik ON7YD - OR7T
________________________________________
Van: [email protected] [[email protected]]
namens Johan H. Bodin [[email protected]]
Verzonden: donderdag 16 december 2010 13:26
Aan: [email protected]
Onderwerp: Re: LF: Sound Card Impedance
I measured the input impedance of the mic input on a Dell laptop:
AC input impedance: 4.3 kOhms (-6dB with 4k3 resistor in series)
Mic bias voltage: +3.8V (open circuit)
Output current: 809uA (shorted to GND)
This suggest that there is a 4k7 pull-up resistor to +3.8V for mic DC bias.
It may vary somewhat between different brands and models of course but all
soundcard mic inputs that I have seen so far puts out some DC bias for electret
microphones.
73
Johan SM6LKM
----
Ken wrote:
> Hello all.
> Does anyone know the approximate impedance of the mic input jack on a pc
> sound card.
>
> 73.
> Ken
> M0KHW
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