OpenEEG - EEG hardware and software

Hi,

Endolith, 17.06.2008 03:16 :
> If I have an EEG or EMG circuit connected to a laptop, and the laptop is 
> running on batteries and not plugged into anything else, meaning the 
> entire assembly is floating electrically, do I still need isolation 
> between the EEG and the laptop?

IMO: No.

However you should make sure that the user can not accidently plug some cables 
into the laptop when connected to the EEG amplifier.


> I don't have to worry about line 
> current spikes or lightning in this case, and the largest voltage I 
> would ever see is the laptop's battery of 18 VDC or so, right?  This 
> would just be for experimenting; not for a finished product.


OK.

Regards,

	Joerg

How about the 500 - 700 Vac display backlight supply??
I know it would take some kind of miracle for this to connect itself to the
serial port but.......

> -----Original Message-----
> From: openeeg-list-bounces@... [mailto:openeeg-list-
> bounces@...] On Behalf Of Joerg Hansmann
> Sent: Tuesday, June 17, 2008 12:24 PM
> To: Discussion of EEG hardware, software, training protocols, NFB
> theory - for developers and users.
> Subject: Re: [Openeeg-list] Isolation needed when working with laptop?
> 
> Hi,
> 
> Endolith, 17.06.2008 03:16 :
> > If I have an EEG or EMG circuit connected to a laptop, and the laptop
> is
> > running on batteries and not plugged into anything else, meaning the
> > entire assembly is floating electrically, do I still need isolation
> > between the EEG and the laptop?
> 
> IMO: No.
> 
> However you should make sure that the user can not accidently plug some
> cables
> into the laptop when connected to the EEG amplifier.
> 
> 
> > I don't have to worry about line
> > current spikes or lightning in this case, and the largest voltage I
> > would ever see is the laptop's battery of 18 VDC or so, right?  This
> > would just be for experimenting; not for a finished product.
> 
> 
> OK.
> 
> Regards,
> 
> 	Joerg
> 
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Hi,

Paddy Duncan, 17.06.2008 13:32 :
> How about the 500 - 700 Vac display backlight supply??
> I know it would take some kind of miracle for this to connect itself to the
> serial port but.......

Very improbable risks can be tolerated to some degree.

And this product is not for the public but for experimenting only:

Endolith wrote:
 >>  This
 >>> would just be for experimenting; not for a finished product.
 >>


Regards,

	Joerg



> 
>> -----Original Message-----
>> From: openeeg-list-bounces@... [mailto:openeeg-list-
>> bounces@...] On Behalf Of Joerg Hansmann
>> Sent: Tuesday, June 17, 2008 12:24 PM
>> To: Discussion of EEG hardware, software, training protocols, NFB
>> theory - for developers and users.
>> Subject: Re: [Openeeg-list] Isolation needed when working with laptop?
>>
>> Hi,
>>
>> Endolith, 17.06.2008 03:16 :
>>> If I have an EEG or EMG circuit connected to a laptop, and the laptop
>> is
>>> running on batteries and not plugged into anything else, meaning the
>>> entire assembly is floating electrically, do I still need isolation
>>> between the EEG and the laptop?
>> IMO: No.
>>
>> However you should make sure that the user can not accidently plug some
>> cables
>> into the laptop when connected to the EEG amplifier.
>>
>>
>>> I don't have to worry about line
>>> current spikes or lightning in this case, and the largest voltage I
>>> would ever see is the laptop's battery of 18 VDC or so, right?  This
>>> would just be for experimenting; not for a finished product.
>>
>> OK.
>>
>> Regards,
>>
>> 	Joerg
>>
>> -----------------------------------------------------------------------
>> --
>> Check out the new SourceForge.net Marketplace.
>> It's the best place to buy or sell services for
>> just about anything Open Source.
>> http://sourceforge.net/services/buy/index.php
>> _______________________________________________
>> Openeeg-list mailing list
>> Openeeg-list@...
>> https://lists.sourceforge.net/lists/listinfo/openeeg-list
>> Go to the above address to change your
>> subscription options, e.g unsubscribe.
> 
> 
> -------------------------------------------------------------------------
> Check out the new SourceForge.net Marketplace.
> It's the best place to buy or sell services for
> just about anything Open Source.
> http://sourceforge.net/services/buy/index.php
> _______________________________________________
> Openeeg-list mailing list
> Openeeg-list@...
> https://lists.sourceforge.net/lists/listinfo/openeeg-list
> Go to the above address to change your
> subscription options, e.g unsubscribe.
>

On Tue, Jun 17, 2008 at 7:24 AM, Joerg Hansmann <info@...> wrote:

> However you should make sure that the user can not accidently plug some
> cables
> into the laptop when connected to the EEG amplifier.


"The user" would just be me.  :)

On Tue, Jun 17, 2008 at 7:32 AM, Paddy Duncan <padski@...> wrote:

> How about the 500 - 700 Vac display backlight supply??


Fluorescent tube ballasts limit current, too...

On Thu, Jun 19, 2008 at 5:51 AM, Joerg Hansmann <info@...> wrote:

> Very improbable risks can be tolerated to some degree.
>
> And this product is not for the public but for experimenting only:
>

Yeah.  Just making sure I understand the dangers before experimenting on
myself.  I'm sure I'm in more danger at work when I stick my fingers into
things that are plugged into 120VAC.  :)

Hi,

Endolith, 24.06.2008 16:58 :
> On Tue, Jun 17, 2008 at 7:24 AM, Joerg Hansmann <info@... 
> <mailto:info@...>> wrote:
> 
>     However you should make sure that the user can not accidently plug
>     some cables
>     into the laptop when connected to the EEG amplifier.
> 
> 
> "The user" would just be me.  :)
> 
> On Tue, Jun 17, 2008 at 7:32 AM, Paddy Duncan <padski@... 
> <mailto:padski@...>> wrote:
> 
>     How about the 500 - 700 Vac display backlight supply??
> 
> 
> Fluorescent tube ballasts limit current, too...

Yes. They limit the current to a few 100mA.
This is good for the fluorescent tube, but way too much for a human.


>  
> On Thu, Jun 19, 2008 at 5:51 AM, Joerg Hansmann <info@... 
> <mailto:info@...>> wrote:
> 
>     Very improbable risks can be tolerated to some degree.
> 
>     And this product is not for the public but for experimenting only:
> 
> 
> Yeah.  Just making sure I understand the dangers before experimenting on 
> myself.  I'm sure I'm in more danger at work when I stick my fingers 
> into things that are plugged into 120VAC.  :)

Putting your finger into a 120VAC (230V here in Germany) powered device
does not need to do do any harm if all other parts of your body (and the finger) 
are not in contact with any conductor tied to another potential (e.g. earth, GND)

The key for safety is avoiding closed current loops through the users body.

When there is no current flow, there is no damage.


Regards,

	Joerg