From: Joerg Hansmann (info_at_jhansmann.de)
Date: 2002-03-12 11:01:34
Hi,
----- Original Message -----
From: sleeper75se <sleeper75se_at_yahoo.se>
To: <buildcheapeeg_at_yahoogroups.com>
Sent: Tuesday, March 12, 2002 9:21 AM
Subject: [buildcheapeeg] Re: virtual ground circuit
> Hi Sar and Joerg,
>
> just a quick question:
>
> Joerg (?) wrote:
>
> > >In the LTSPICE simulation the addon did not perform very well ;-)
> > >(Neither did the LT1114)
>
> Did it? I thought it was a bit slower in the beginning, but the
> oscillation subsided just as fast as with the other opamp.
No. It had significantly less phase margin.
> Do you
> guys have any top-of-the-head suggestions for replacements? Something
> with < -96dB channel crosstalk and > 96dB SNR would be nice.
The LT1114 performs nicely if the passive components are
optimized for it:
<snipped from other posting (not yet posted, just under construction):>
...
I have tuned the ESR compensated circuit for usage with the
LT1114 (see picture VirtualGnd-Tuned02_bode_plot.png) by
increasing the ESR of the 47uF C by about factor 10 (5000mOhms)
and inserting a damping R in series with C11 to remove a HF resonance
at about 10Mhz (a series resonator formed by C11 and its ESI of about
10nH).
...
HTH.
Regards,
Andreas
>
> PS.
>
> ACK means ACKnowledged. But perhaps we should use ARGH! more in our
> conversations?
Better not...
> ;o) Just kidding.
;-)
> DS.
>
> PPS.
>
> A short progress report on TinyEEG:
>
> I worked a bit on the power supply this weekend and have successfully
> managed to reduce the HF noise to levels undetectable by oscilloscope.
Congratulations !
> Just to be sure, I will add a second filter stage identical to the
> first, that in theory should reduce the HF-noise to 10-20uV.
>
> Currently, there's only visible noise (2mVp-p) in the 0-10kHz range
> left, but I hope a linear regulator can handle that.
ACK.
> Yes I know my project is moving forward at a crawl right now, a lot
> going on... Joerg, how are you doing?
Moritz and me had a working session this weekend and etched
4 modEEGanalog pcb s for prototyping.
I will insert the components (for 1 pcb) these days and do some
testing.
Regards,
Joerg
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