From: sleeper75se_at_yahoo.se
Date: 2001-12-01 18:38:44
Hi, Jim-P, Doug and Jim-M,
this thread is getting rather long don't you think? :-)
Anyways, here are my replys for the last two of posts.
--- In buildcheapeeg_at_yahoogroups.com, Doug Sutherland <wearable_at_earthlink.net> wrote:
> > http://www.biosemi.com/publications/artikel1.htm
> > I've uploaded my attempt to reproduce them.
>
> Cool, you've tried making them! I will check that out.
> Can you share a bit on results: did you try feeding
They are not built yet, since I'm working on them right now. :-) I'm
planning to do so next week, however. It is intended for EEG, but
they will probably work with ECG too.
Some preliminary specs from simulation (they're probably wrong,
because I'm simulating with TL071 amplifiers, which differ a bit from
what I intend to use - OPA2277.)
AC amplification: 100 at 0.4Hz, rising to 125 at 1 Hz, is then
constant for higher frequencies.
'DC' amplification @ 50mHz: 19 times, versus 4.8 times for the
Biosemi device. I get the 4.8 figure at 10mHz instead. This limits
the offset it can accept to about 100mV with +/- 3.6V power, but that
is just a ballpark figure - varies with amplifier type and supply
voltage.
Max bio-signal it can measure (without offset): About 50mV. Depends
on supply voltage though.
Maximum common mode voltage: Depends on the amplifier, but I
simulated a common-mode signal of 50Hz at 1V without any problems. It
got 'amplified' to 20uV. (CMRR = -97.5dB). The real thing will
probably do better, but common mode signals are less of a problem to
begin with because the amplifiers are located so close to the
electrodes.
Noise: Haven't got a clue. :-)
I'll get back to you about the real thing in a week or so.
--- In buildcheapeeg_at_yahoogroups.com, "Jim Meissner" <jpmeissner_at_mindspring.com> wrote:
> Dear Jim Peters and group:
>
> Could someone guide me as to how to find the published design?
> I went to SourceForge and could not figure out how to get it?
> Jim Peters found the file but could not read it. I am not a
> software guru! I am good at low noise analog stuff though.
Hmm, strange. I will upload to the schematics and PCB-layout in PDF-
form to the group's file-section (hardware folder) for you. I hope
you can access it. We don't want any skills get lost here you know.
;-)
> I also found many Mega bytes of REAL EEG data. The data is about
> several different people and one of them is a very gifted Medium
> from England (very interesting data). I would be happy to make
> that data available if someone (a computer guru) could tell me
> how to do it. I could put this data on my website to be downloaded?
Cool!!!! You can either put it on your website or we can put some of
your material in the file-section of this group. What is it you want
to know?
>
> Switching away from HC11 to Amtel. The code to make the HC11 play
> is not complicated, (less that 1/2 page of code), but I had to hire
> a consultant to teach me how to. I hope that after 5 years I still
> remember how! Is there someone on this list who can program the
> Amtel in assembly language? Do you have the software tools and
> debuggers? Can an old dog learn new tricks?
Yes, yes and yes. :-) If you are refering to Atmel, debuggers,
simulators and stuff are available here:
http://www.atmel.com/atmel/products/prod203.htm
>
> The discussion about fancy filtering should be shelved until you
> guys look at REAL data.
>
Consider it shelved. :-)
>
> If you want to build stuff, I can give you a schematic of what I
> have. What format should that be in? I could do a paper sketch
> and scan it. For professional work I use Orcad, but that has been
> a few years.
It is always interesting to look at other people's work, so it would
be great if we could see it.
I'm using Protel 99, it has Orcad and DXF import. Have never tried to
use it though, but if you put the schematics on your website I can
download it and try to convert it to PDF.
--- In buildcheapeeg_at_yahoogroups.com, Jim Peters <jim_at_uazu.net> wrote:
> Answering a couple of posts in one go ...
Me too ... :-)
> I've had a read through the PDF on the web-site now:
>
> http://openeeg.sf.net/design_challenge/design_challenge.pdf
>
> This is all excellent stuff. If there is a microcontroller compiler
> available for this processor for Linux, I'll certainly be up for
doing
> some coding of modules to download. And, like my SBaGen tool,
> (sbagen.sf.net), I'm very happy to use the GPL and open-source
> everything.
Hmm, only windoze software at the manufacturers site. However, it is
likely that the assembler/compiler itself is a command-line program,
so maybe they will run with Wine or some other emulator?
>
> I also downloaded the schematics from the project page:
>
> http://sf.net/projects/openeeg/
>
> But I obviously don't have the correct software to view these.
The software is Eagle Layout Editor, available here: (Win/Linux)
http://www.cadsoft.de/
Phew, a lot of typing there...
/Andreas
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