Re: HackEEG: 8 - 32 channel (and beyond) EEG shield for Arduino Due and Mega

On Thu, Jan 23, 2014 at 1:25 PM, Grant Stockly <[email protected]> wrote:

> How do you handle using the same reference on multiple boards?  Or do you?
>

Each board in the stack has its own power supplies. For the reference
electrodes, you use Y-connectors to connect them together. So yeah, you use
the same reference electrode. I have to try this out in practice alongside
some research EEG hardware to see how it works in practice. I have a friend
who's a neuroscience researcher that offered to help me with this.

Are you using a 6 layer PCB or 4?  I'm trying to keep it nice with 4, but I
> have an urge to just go the easy way.
>

It's a 4 layer design - top and bottom signal layers, ground and digital
power planes. I was very careful to not underlay any signals under the
analog input traces, and tried to be careful to keep high-frequency signals
away from the analog signals, supplies, and grounds. It works ok for my use
- I will be doing some work to compare it to professional EEG gear soon.


>  I can get 4 layer boards manufactured by US vendors that I trust
> affordablly.  6 layer, not so much...
>

You can get good 6 layer boards from Gold
Phoenix<https://www.goldphoenixpcb.com/>in China. That's where I'll
probably be getting my production 4-layer
boards from.


> Your board sounds very nice.
>

Thanks. Yours looks cool too. I like the battery-power and the bluetooth.
It looks similar to what the OpenBCI folks are doing.

I eventually want to build a little battery-powered wireless unit... but
wanted to build a hacker system first to try out a bunch of ideas...

cheers
adam
-- 
Adam Feuer <[email protected]>

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