Several weeks ago I posted several|questions about a DIY EEG reader that I found on Instructables. To my surprise, it appears to actually be a fairly well-designed circuit.
The main stages of this circuit are as follows:
- Instrumentation Amplifier
- 60 Hz Notch Filter #1
- 7 Hz High Pass Filter
- 31 Hz Low Pass Filter
- 1 Hz High Pass Filter
- 60 Hz Notch Filter #2
In addition, the members of this community added some additional recommendations, such as:
- Use an ADC early on
- Implement an Op Amp
I was planning on building this EEG reader, including the above suggestions from this community, until I stumbled across a most-awesome Kickstarter for an open source EEG reader called OpenBCI. And so I am now strongly considering doing all of my R&D/proof-of-concepting with OpenBCI instead of my own DIY EEG. However, I want to make sure OpenBCI is of the same quality (if not better) as the DIY EEG mentioned above (including the recommended tweaks from this community).
Here is the open source circuit design for the OpenBCI board:
On one hand, I believe I see:
- Instrumentation Amplifier
- High Pass Filters
But on the other hand, I am not seeing:
- Notch Filters
- Op Amps
- An ADC
And so, all this to ask: Am I missing something here, or is the OpenBCI design not of the same level of quality of the DIY EEG that I found (plus the tweaks recommended by this community). Or, is the OpenBCI design taking a different approach that will still yield the same "quality" (accurate bioelectrical wave measurements, granularity, noise reduction, etc.) in the end?