From: Jim Meissner (jpmeissner_at_mindspring.com)
Date: 2002-02-03 00:39:40
Dear Jim Peters:
Had another thought. That's the second one today!
I modified the probe placement of the ground. Instead of one electrode in the center of the forehead, I use two ground electrodes, one on each templenear the hair line. The reason was that if you get a little sloppy with the paste, you inadvertently short out the forehead electrodes. With just one of me it is hard to see what you are doing and the extra spacing really helps. I have all the electrodes mounted on a headband with a Velcro fastener.
( BTW if you are really serious you will shave your head or at least the back where the probes go! )
Another way to reduce the hum pickup is to find a quiet spot in your house where there is no wiring.
Juergen P. (Jim) Meissner
Check out my Website at www.MeissnerResearch.com
Read about the benefits of the Brain State Synchronizer sounds for improving your life and health.
----- Original Message -----
From: Jim Peters
To: buildcheapeeg_at_yahoogroups.com
Sent: Saturday, February 02, 2002 3:58 PM
Subject: Re: [buildcheapeeg] NaffEEG
Jim Meissner wrote:
> I looks like you got some real good information from Andreas and Joerg.
Yes, sorry for not replying yet to anyone. I'm working through the
tests that Joerg outlined, and I've put the circuit in a metal box.
Thanks for the advice on the electrodes, all of you.
> Over the years I have been using the Mind Mirror electrode system.
> You live in England? You should get some from them. Also get the
> book by Maxwell Cade "The Awakened Mind".
I'll ring them Monday to get the book, and see what they say about
electrodes. The site is here, in case anyone else needs to find them:
http://home.clara.net/biomind/
I'm realizing that I may have to start again with the electrode
cabling, looking to minimize any possible pickup of hum. I copied the
cabling idea from the book "How to build a lie detector, brain wave
monitor and other secret parapsychological electronics projects" --
but they used filters, so perhaps they didn't need to be quite so
careful.
Yes, Jim, I did already dig out your electrode placement instructions
posted earlier. However, without electrode paste I didn't think I'd
have much luck with the rear placement positions.
To Joerg -- re isolation, I'm using no isolation at all -- the AD620
output goes straight to the laptop sound card input. I did consider
that isolation might have some effect on the noise and hum, so I
disconnected everything from the laptop (power, modem, network,
hi-fi), leaving it running just on batteries, and there was no obvious
difference. I'll try again once I've got everything more sorted.
For a signal generator, I can use my other PC with a potential
divider. I can measure the AC voltage before the divider and
calculate the resultant.
I'll give some more specific feedback once I've got somewhere with the
tests and maybe bought/built myself some better electrodes + paste.
Cheers -
Jim
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