Re: DRL problem

Hi Andre,
 
I was away for the weekend, so sorry for the slow reply.
 
If the DRL is saturated neagtive, then it won't be doing it's job. I would expect a VGND connection would be better than a saturated DRL.
 
You need to refer to http://openeeg.sourceforge.net/doc/modeeg/modeeg_building.htmlthen scroll down to section 2.5 for trimming the DRL. It sounds like you will need R201 in your implemetation of the circuit in order to get the DRL output to the correct voltage.
 
R201 is shown on the amplifier schematic - http://openeeg.sourceforge.net/doc/modeeg/modEEGamp-v1.0.png - which also has the note about trimming the DRL.
 
Don't forget to trim the DRL relative to VGND, not AGND (I think you know this, but I thought I'd say just in case).
 
Good luck,
 
Mike

From: André Ribeiro <[email protected]>
To: "Discussion of EEG hardware, software, training protocols, NFB theory - for developers and users." <[email protected]> 
Sent: Friday, 8 March 2013, 14:15
Subject: Re: [Openeeg-list] DRL problem


Hi Mike,

Yes there is only one input to the IC201B (from the only one channel I have in the design).

No there is no 0 with all short! I get negative saturation at the outuput of IC201 and then the DRL output at -500mV. What may then be the problem?

Regards,

Andre


On Fri, Mar 8, 2013 at 9:45 AM, Mike <[email protected]> wrote:

Hi Andre,
>
>I can see no problem with using LF412, or having 10M in parallel with C216.
>
>Is there only one input to IC201B in your version of the design?
>
>Have you checked that the DRL output is 0V when your EEG inputs are connected to DRL as described in the schematic?
>
>If the answer to both of these questions is "yes", then I cannot think of anything else to suggest - sorry.
>
>
>Regards,
>
>Mike
>
>----- Original Message -----
>
>Date: Thu, 7 Mar 2013 21:48:59 +0000
>From: Andr? Ribeiro <[email protected]>
>
>Subject: Re: [Openeeg-list] DRL problem
>To: "Discussion of EEG hardware, software, training protocols,    NFB
>    theory - for developers and users."
>    <[email protected]>
>Message-ID:
>    <mailto:CALUfTPxwp1-1SNP-dsU8w46T%2B-KM%[email protected]>
>Content-Type: text/plain; charset="iso-8859-1"
>
>Still with problems people. Is there someone that can help?
>
>Regards,
>
>Andre
>
>
>On Thu, Mar 7, 2013 at 12:43 PM, Andr? Ribeiro <[email protected]> wrote:
>
>> Wait. I know that. I am only using one channel, I do not have another
>> floating. In my circuit there is one channel only not two. I wanted to do
>> measurements of relaxation and meditation on frontal region therefore I
>> need only one channel.
>> There is no floating channels.
>>
>> Regards
>> Andre
>>
>>
>> On Thu, Mar 7, 2013 at 11:31 AM, [email protected] <
>> [email protected]> wrote:
>>
>>>  it is especially a problem IF you only use one channel. you have to
>>>  ground unused channels or the dlr circuit wont work!
>>>  the dlr circuit is an output channel, floating eeg inputs cause the dlr
>>>  signal to take false values.
>>>
>>>  regards,
>>>  jan
>>>
>>>  Am Donnerstag, den 07.03.2013, 12:25 +0100 schrieb Andr? Ribeiro
>
>>>  <[email protected]>:
>>> > Hi,
>>> >
>>> > I am using only one channel. So that should not be the problem. I am
>>> > also not using shielded electrodes. I have the cables twisted to
>>> > reduce RF.
>>> >
>>> > Regards,
>>> >
>>> > Andre
>>> >
>>> > On Thu, Mar 7, 2013 at 9:56 AM, Mike  wrote:
>>> >  Hi Andre,
>>> >
>>> >  Have you ensured that unused EEG inputs are connected to ground
>>> > (0V)? The DRL won't work with inputs left floating (unconnected).
>>> > This
>>> > is stated in the amplifier schematic
>>> > http://openeeg.sourceforge.net/doc/modeeg/modEEGamp-v1.0.png
>>> > [2] bottom left.
>>> >
>>> >  Regards,
>>> >
>>> >  Mike
>>> >
>>> >  ----- Original Message -----
>>> >  Date: Wed, 6 Mar 2013 12:26:23 +0000
>>> >  From: Andr? Ribeiro
>>> >  Subject: [Openeeg-list] DRL problem
>>> >  To: [email protected] [4]
>>> >  Message-ID:
>>> >
>>> >  Content-Type: text/plain; charset="iso-8859-1"
>>> >
>>> >  Hello,
>>> >
>>> >  I am a Biomedical student from Portugal and I was developing a eeg
>>> > board
>>> >  (only the analog part) based on the schematics of the Modular EEG. I
>>> > have
>>> >  however one problem with the DRL, as I can't make it to work
>>> > properly.
>>> >  Indeed I have better results if I connect directly the 3rd electrode
>>> > to the
>>> >  GND.
>>> >  Before someone asks I did however some modifications and I would
>>> > want
>>> > to
>>> >  know if this could be the problem for the DRL or not.
>>> >  Ok so from the INA114 I use a buffer just like Modular EEG, however
>>> > I
>>> > am
>>> >  using the LF412 then on the inverting amplifier I also connected a
>>> > 10M
>>> >  resistor parallel to c216 (1nF) for stability (I think) and again
>>> > used a
>>> >  LF412.
>>> >
>>> >  I would appreciate any input.
>>> >
>>> >  Thanks,
>>> >  -------------- next part --------------
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>>> tackle endpoint security challenges, access the full report.
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>------------------------------------------------------------------------------
>Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester 
>Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the 
>endpoint security space. For insight on selecting the right partner to
>tackle endpoint security challenges, access the full report.
>http://p.sf.net/sfu/symantec-dev2dev
>
>------------------------------
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>
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>Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester
>Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the
>endpoint security space. For insight on selecting the right partner to
>tackle endpoint security challenges, access the full report.
>http://p.sf.net/sfu/symantec-dev2dev
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------------------------------------------------------------------------------
Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester  
Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the  
endpoint security space. For insight on selecting the right partner to 
tackle endpoint security challenges, access the full report. 
http://p.sf.net/sfu/symantec-dev2dev