From: lenngray (lenngray_at_yahoo.com)
Date: 2002-01-03 16:40:34
--- In buildcheapeeg_at_yahoogroups.com, "Brian Gr" <brian_gr_at_hotmail.com> wrote:
> I don't have the BM schematics here but if memory serves
> correct, their wasn't any ESD protection on the input stage.
> The electrode inputs were connected to the instrumentation
> amplifiers (AD621 I believe) via 10 Meg resistors, so that
> would significantly limit any current in event of AD621
> catastrophic failure and possibly provide some ESD protection.
It turns out the old BM was connected to the user via .01uf
_caps_, and the 10M resistors were only across the AD620 inputs
to ground.
Also, I have it on good authority that the current BM that
they sell is _not_, however, like that published circuit, and
has an input impedance of 5 gigohms, and thus likely also has
some nice fancy input protection.
- Lenny Gray -
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:36 BST