From: Jim Peters (jim_at_uazu.net)
Date: 2002-03-06 10:53:09
Chris Kirtley wrote:
> One thing I wondered about was whether anybody had
> tried using the sound card as a cheap ADC? I managed
> to get some oscilloscope VB source code to read in the
> data from the microphone jack, and I thought it might
> be interesting to see how useful it is for
> physiological signals. My main worry is that there is
> probably a high-pass filter in there - anybody know?
Search the archives !! We've been over this question several times.
In brief, you need isolation, otherwise if your subject happens to
touch any live connection (e.g. badly grounded equipment), then the
live signal takes the shortest route to ground, which is through the
brain to the electrodes to the soundcard input. This is not a good
idea (electro-shock therapy?)
Apart from that, if you want to take the risk, it doesn't take long to
put a few test signals through your soundcard input to see what the
filter is like. I tried it, and on my particular soundcard it seemed
like it might be good enough for very rough testing, but not good
enough for general use. I went so far with this, but then left it and
got back to coding, which is what I'm better at.
Jim
-- Jim Peters (_)/=\~/_(_) jim_at_uazu.net (_) /=\ ~/_ (_) Uazú (_) /=\ ~/_ (_) http:// B'ham, UK (_) ____ /=\ ____ ~/_ ____ (_) uazu.net
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