From: arethereanytagsleft_at_yahoo.co.uk
Date: 2001-11-09 18:28:50
I wish I had discovered this list a few weeks ago...
A few weeks ago I figured I wanted an EEG. I'm a programmer,
not an electrical engineer, so first I looked for a
reasonably cheap kit to buy. There are several things I
would like to try: mind-mirror type experiments, alternative
input devices for severely disabled people (see
http://home.freeuk.net/thousandminds), training neural nets
to recognize different mental states, etc etc.
I came across the HAL-4 stuff
(http://www.cc-concepts.com/products/hal4/), but they
weren't making it any more. I considered buying the
brainmaster kit, but it was a bit expensive and it seemed
more interesting/informative to build one myself.
I got the circuit diagrams which HAL4 was based on. This was
from 1988 so the components are dated. I also got the
follow-up articles from Circuit Cellar magazine (obtained
CDs with archives of appropriate years - issue #27 contains
HAL4 circuits, and issue #116 contains an updated circuit
for a stand-alone LED based unit - I can post the diagram if
anyone is interested).
I decided to build the later circuit (it's a lot simpler and
uses more modern components), but to just build the
amply/filter/amplify part of the circuit and not do the
ADC/FFT on the circuit board. I figured once I got any kind
of reasonable signal into the computer I could cope. The
plan was (is) to send the signal through the analog-in
soundcard port and let that do the ADC stuff. Then I would
do FFT in software. I am only building a 2 channel device.
I'm not convinced that using the soundcard will work ok
(because it's only designed for 20Hz-22khz signals), but
thought I could get some other chip to do the ADC conversion
if the using the soundcard gives unsatisfactory results.
Status at the moment: I have received the components, but
haven't anything assembled yet (an EE friend of mine is
helping).
Anyway, I have several questions:
1. Does anyone know if soundcard approach is likely to work?
2. Where are the designs that this group has come up with ?
I looked on the web site, but don't see any circuits.
3. What is the state of the software this group has produced ?
4. How can I help ? I have about 10 years professional C++ experience
(mixed with a bunch of other languages) in various areas, mostly
scientific
(optimization, GAs, neural nets, 3D visualization/analysis, OpenGL,
GUIs etc)
Regards
Joss (joss at supportwizard dot com ) My ICQ number is
13407891 an I'm happy to talk about this stuff
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:32 BST