From: sleeper75se (sleeper75se_at_yahoo.se)
Date: 2002-01-29 18:46:34
--- In buildcheapeeg_at_yahoogroups.com, "Joerg Hansmann" <info_at_jhansmann.de> wrote:
> > Joerg, how is your version coming along?
>
> At the moment I have conflicting ideas regarding the
> digital part of the modularEEG.
[snip]
> However I fear that these are two rather different designs
> that cannot be changed easily into each other.
>
Ok, here are my thoughts:
If you want bidirectional I/O I think wide-spacing optocouplers is
best, because the fiberoptic connectors are quite expensive. Expect
to pay $4 extra for each LED/photodiode, $16 in total, then add the
cost of fiber... If you scale down to output-only, I think fiber is
best.
Regarding RS232, why not let it run on a transformer at all times?
The only difference between battery mode and DC/DC mode would then be
that for battery mode you don't mount the DC/DC converter and connect
the batteries to where the converter's output would be.
Another option (that I will use) is to steal RS232 power (+5V) from
the keyboard or mouse ports.
Yet another option, though perhaps confusing for some users, would be
to steal the +5V power for the whole thing from the usb-port. It
provides +5V, 1A current, max. Later on you could throw in one of
these: http://www.ftdichip.com/Documents/ft232r08.pdf
I hope my rambling makes sense... :-)
> The analog part of the modularEEG needs some changes
> too:
[snip]
> Then some SPICE simulations should be done to see if the
> DRL circuit is stable under all possible conditions.
Is the structure of the DRL finished though? I'd like to have a look
at it :o)
> When all this is done, the resulting changes will be
> inserted in the eagle schematic and a modified pcb layout
> will be done. After that the first modularEEG prototype
> can be built.
Ok, good luck!
/Andreas
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:37 BST