I am Not Good At This, and I am trying to breadboard this circuit here:
But I am stuck on the power supply. The instructions state:
Regarding power: the easiest way to power the circuit is with 2 9V batteries. To feed your op-amps -9V to 9V of power, connect one battery the correct way, and one backwards. That is, connect the positive lead of one battery to your positive power supply line and its negative lead to GND (ground). With the other battery, connect its positive lead to GND, and its negative lead to the negative power supply line. To "set" GND, you will eventually connect an electrode from your leg directly to the GND line. This will ensure that "0V" is your leg's voltage (unaffected by any head activity), and that all readings will vary from there.
Which is fine, until I can't actually figure out what rails to attach the two 9Vs to. I think I get the idea that GND happens between the first + and the second - terminal, i.e.
I've been testing it wired as the 2nd configuration, and it Mysteriously Does Not Work. Are the batteries hooked up wrong? If so please help me wrap my brain around how this works and I'll see if my chips are fried or not. Hopefully not.
If the batteries are hooked up right, don't worry about trying to troubleshoot my other problems. I can test it indefinitely if i'm at least assured the power is right.
Here's an example of how one person did it:
But I can't be sure how those wires on the right-hand side end, and I'm not experienced enough to guess.
Thanks very much!