This week I did further research about our preamplifier circuit. After
discussing things with Professor Krauss, I have determined that we probably will have to
use at least some negative voltage. Brain waves are bipolar, and although we
could use a DC offset, i feel like if we use that directly from the scalp we
risk swamping the already faint signal with noise. I found a IC chip, the ICL7660 that will easily just convert the +5v
that we have to a -5 V. It cannot
provide high current, but we'd barely need any to power the op amp chips. I
purchased 10 of these chips for 1.76 from china. We do not need this chips to
construct the filter, we can just use a DC power supply, we'll only need the
chips when we build the final prototype.
We'll add a DC offset right before the signal gets sampled by the
microcontroller.
Hopefully we can construct this circuit ASAP using the schematic from
instructables as is, we will have to include credit to the author of that
article.
datasheet above.
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