Hi Andreas,


<color><param>7F00,0000,0000</param>> >But then you have to due all kinds of things like glueing the LED

> >to the fibre and so on which aren't perfect or professional :)

> 

> Hehe, well, but its FUN! :-) 


</color>Maybe for us, but not for everyone out there, I think. We really have 
to define what our goals are. For us, to have fun, or a design that 
can maybe be later distributed to more people.<FontFamily><param>Symbol</param>


<color><param>7F00,0000,0000</param><FontFamily><param>Arial</param>> It's possible to save on that part but theoretically you can injure 

> somone badly by hooking up a pair of low-impedance electrodes and 

> connecting a 9V battery directly to them. We'll have to make sure 

> that even if the head-stage amplifiers get shorted to ground and 

> power, the user is safe. I think the maximum allowed limit is 0.1mA 

> current through the human body. Above that, things get uncomfortable 

> fast. 1mA can be sensed and 5mA is painful.


</color>Look at the schematics. There are some 10Meg resistors to 
prevent this. Of course I'm thinking about battery operation for the 
future. That will get rid of the noisy DC/DC converter that also isn't 
safe enough for medical standards.<FontFamily><param>Symbol</param>


<color><param>7F00,0000,0000</param><FontFamily><param>Arial</param>> 

> >Also it's convenient and modern and interesting.

> 

> Yes, it is. Are you thinking about a battery operated device here? I 

> think I read in a data sheet that the LED in a IrDA transceiver can 

> consume 100mA on average, and that is quite a lot.


</color>IRMS6118 from Infineon 


http://www.infineon.com/cgi/ecrm.dll/ecrm/scripts/prod_ov.jsp?oid=
13990&cat_oid=-8199


needs about 2.5 mA during transmission according to the data 
sheet. If we use NiMH rechargeable batteries with 1500mAH 
capacity, we could run our EEG for quite a long time without 
recharging. I'd like to use 4x1.2V batteries, but I'm not sure about 
the OpAmps, how much voltage we need for them. For voltage 
regulation I thought about a MAX603/4. Any other suggestions ?<FontFamily><param>Symbol</param>




<FontFamily><param>Arial</param> Moritz<FontFamily><param>Symbol</param>

<nofill>
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Moritz von Buttlar
moritz@v...