This high pass filter usually consists mainly of a small electrolytic
capacitor in series with the input of the sound card. I can't see any reason
that the capacitor cannot be shorted out (DC coupled, high end audiophiles
love that) and perhaps the configuration of the rest of the input circuit
tweaked somewhat to provide a cheap high resolution ADC.

However, I have been completely too lazy and hopeless to figure out how to
drive the thing from the software side.

Mark
----- Original Message -----
From: "Travis Farmer" 
To: 
Sent: Saturday, May 05, 2001 1:00 PM
Subject: RE: Voltage controled attenuator/amp


> I have inquired and tried it.
> Most soundcards have a high pass filter set at 10 Hz. This means any
> frequency below 10 Hz is lost.
>
> -Travis
>
> -----Original Message-----
> From: psn-l-request@.............. [mailto:psn-l-request@.................
> Behalf Of David russel
> Sent: Friday, May 04, 2001 8:13 PM
> To: PSN-L@..............
> Subject: Voltage controled attenuator/amp
>
> Al's inquirey about the VCA got me think'in again about of a method
> of getting data from the s'smtr into the computer.
>
>         I was wondering if it was possible to Amplitude Modulate, with
> the seismometer signal, a carrier of an arbitrary  audio frequency of
> about 10Khz and input it into the SoundBlaster at the back of your
> computer. Then doing something fancy with software like peak averaging
> then plotting it.
>
> Anyone ever done somth'in like this?
>
> Casey
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