From: Jim Meissner (jpmeissner_at_mindspring.com)
Date: 2002-01-11 21:00:41
Dear Andreas:
It is really getting there!
My only request would be to provide an output from U3A. You changed the opamp designation, so there is a mix-up. I see no reason to have an output from the integrator (now called U3B). I was requesting an output line fromthe ( now ) variable gain stage with the 470 pf and 22 K feedback resistor. This line I would run to the speakers for bio-feedback. Also during testing you can hook a scope there for initial trouble shooting and probe testing.
So how soon can we have some boards to play with?
Your question about polypropylene, yes film capacitors are the best. I worked for a company that made capacitors and the very best were metalized Teflon.
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.
----- Original Message -----
From: sleeper75se
To: buildcheapeeg_at_yahoogroups.com
Sent: Friday, January 11, 2002 8:26 AM
Subject: [buildcheapeeg] New input stage - v1.2
Hi Jim and Joerg,
I've uploaded version 1.2 of the input stage.
Some tweaks, going from input to output:
*FET-diodes are gone, resistors increased to 5.6Kohms.
*4.7uF caps in the HP-stages are replaced with 1uF, non electrolytics.
*Added an output at U3B pin 7 (integrator output)
*1nF is changed to 470pF in second gain stage. Bandwith should be
12KHz.
*Outputs were added around the 1K resistor in the second gain stage,
so that one may replace it with a potentiometer.
Changes in the power filter:
The resistors directly following the inductors are reduced to 10 ohms
again and 100uF capacitors are added. This RLC-combination forms a
low-Q filter with a cutoff frequency around 150Hz.
Since I want to allow low-voltage operation, the filters are now in
two branches rather than a bus. The resistors have changed to 75
ohms, so the voltage is now 2.3V at Va when the battery voltage 2.6V.
Does everything look ok now? I'd really like to start the layout...
/Andreas
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This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:36 BST