From: Jim Meissner (jpmeissner_at_mindspring.com)
Date: 2002-01-31 17:59:49
Dear Joerg:
> > So by inspecting the BrainMaster input stage, I guess at some low
> > frequency the source resistance will be 10 Meg as the Xc of the
> > 0.01 mf capacitor increases with lower frequencies. I wonder if
> > you could try to simulate that stage again using larger capacitor
> > values. I would be interested to see what capacitor value will
> > give "good" noise down to 0.1 Hz? Somewhere I have the schematic
> > for the original Mind Mirror. I think they used a 10 or 100 mf
> > capacitors feeding into a discrete transistor for the lowest
> > possible noise.
Let's try this again. I am talking about the BrainMaster input stage. Your schematic showed 0.01uf capacitors and a 10 meg to ground.
Would you be able to do a noise plot for various size capacitors. Let's say 1 uf, 10 uf, and 100 uf.
If the noise were "good" at 1 Hz what would it rise to at .1 Hz?
For the moment please ignore the capacitor characteristics. Assume a perfect capacitor for now.
(BTW I worked for a capacitor manufacturer and there are many capacitor types available, although some become very expensive.)
Based on Andreas numbers, a 10 uf might be a compromise. I have some inexpensive 10 uf metalized Mylar caps that should work better than electrolytics.
Juergen P. (Jim) Meissner
Check out my Website at www.MeissnerResearch.com
Read about the benefits of the Brain State Synchronizer sounds for improving your life and health.
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