From: spicyme_at_i...
Date: 2001-04-30 13:37:10
Hi Gang,
I just received this e-mail from Dr. Steven Harris at Cirrus Logic
to my question about using soundcard for EEG.
quote:
Hi Mohan
Two suggestions:
Use a small Analog to Digital converter module which you can
plug into the printer port on a PC, which comes with some analysis
software.
I think PICO technology make one, see Electronics World magazine for
advertisements.
OR
Increase the value of the DC blocking capacitors in the input
circuitry in the
sound card. Usually the codec chip and drivers pass dc-20kHz, it is
the external
dc blocking capacitors that determine the 20Hz Hi Pass corner
frequency.
Making these capacitors larger will lower the corner frequency.
You still need to block DC, so the capacitors are necessary.
You will a high gain preamplifier to amplify the brain signals.
Also, think a lot about safety. Professional EEG units are
very carefully designed so there is no possibility of electrocution.
PC's are not designed to the degree of safety required by medical
equipment.
Good luck
Steve
Dr. Steven Harris, Director || Cirrus Logic Inc.
Email: snh_at_c... || Anglers Court
Tel Direct: +44 (0)7710 657828 || Spittal Street
Fax: +44 (0)870 0520252 || Marlow SL7 1DB
http://www.crystal.com || England
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