From: Joerg Hansmann (info_at_jhansmann.de)
Date: 2001-06-06 15:54:03
Hi,
----- Original Message -----
From: Psytrix Yahoo <psytrix_v_at_yahoo.com>
To: <buildcheapeeg_at_yahoogroups.com>
Sent: Wednesday, June 06, 2001 2:57 PM
Subject: [buildcheapeeg] Re: Right Leg connection for EEG
...
>Hi, Joerg
> thanks for patience (infinity) with the "starving hobbyist" questions .
> Would you give some references (WWW or texts) about the right leg connection for EEG -
> I found it only for ECG
The purpose of a driven right leg is the same for ECG and EEG:
Reduction of common mode voltage at the amplifier inputs.
Basically the common mode voltage (Vcm) is amplified and inverted and fed back into the right leg
(could be any part of the body that is sufficiently far away from the signal uptaking electrodes)
of the test subject.
This setup forms a servo circuit (closed loop control), that minimizes Vcm.
See chapter: 3.2 "Reduction of the common mode voltage"
at http://www.biosemi.com/publications/artikel3.htm
(IIRR yaniv had discovered this very good series of articles )
>Thanks in advance,
>Waldemar
Regards,
Joerg
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