From: sleeper75se (sleeper75se_at_yahoo.se)
Date: 2001-12-14 01:09:35
Hello all,
--- In buildcheapeeg_at_yahoogroups.com, Moritz von Buttlar <info_at_baltic-microsolutions.de> wrote:
> >I'm working on it... :-)
>
> Great ! Feel free to make the changes already in the schematics and
the layout.
> (Also all your other layout improvements, if you want).
I'll try... I don't get along with Eagle very well though. It is very
different from Protel, that I use every day.
Just a thought: we can save some space if we replace the resistors
and decoupling capacitors with surface mount parts. Size 1206 is
pretty big (5mm x 1.5mm) so they should be fairly easy to solder,
even for inexperienced people. What do you think?
> I think Joerg knows some people in the department for medical
> engineering / Luebeck University. They might even test our device
> for us for free. Maybe they have access to the norm and we could
> get a copy ?
That would be perfect! Any knowledge and information they have is
valuable.
> Something else: What about the input stage of the amplifiers ?
> Should we change it ? How can we change it to keep it safe ?
Yes, I believe they need some work. The highpass filter reduces the
input impedance to 10Mohm, and thats not very good. Compare with the
Brainmaster and its reworked input stage (10Gohm). I suggest that we
lower the gain of the instrumentation amps to 10, put the filter
behind them and then amplify the signal by 1000. The downside is more
noise ...
Safety: INA114 has an input impedance of 1Tohm, so a single 470k
resistor on each input shouldn't do much of a difference for the
measurements, but they will limit the current to safe levels if the
battery gets shorted to the inputs somehow.
---------------------
--- In buildcheapeeg_at_yahoogroups.com, "Joerg Hansmann" <info_at_jhansmann.de> wrote:
> It is not the original document but a
> "Practical Guide to IEC601-1 Electrical Safety Testing"
>
> http://www.bapcoinfo.com/IEC601safetytestingarticle.htm
Thanks. It will be useful.
I've been looking at 5000V (or more) opto-couplers at agilent's
website and curiously, they only specify medical applications for the
really really expensive ($60-$400) parts.
Maybe it's just a marketing thing, but I'm utterly ignorant in this
area..., do you think your friends at the university could give us a
recommendation here?
Be well,
Andreas (staying up late... or early.... zzzzz)
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:33 BST