I'm pretty beginner here but I'm trying to implement this circular 

[![enter image description here](https://i.stack.imgur.com/J2i8p.jpg)](https://i.stack.imgur.com/J2i8p.jpg)

The issue that I didn't find [lm224](http://www.ti.com/lit/ds/symlink/lm224.pdf) so i replaced it with lm324cd and I think it's not doing the same Electrical properties, this part taking charge of transmit electrical signals from over my head and transmit it to arduino, (Funny part) I can see electrical signal over my head, however I already done with this but it's seems that I've make some mistakes here, but I don't know really where.

This the full circular (I'm afraid that it's not helpful so feel free to ask any question)

[![enter image description here](https://i.stack.imgur.com/JGRDE.jpg)](https://i.stack.imgur.com/JGRDE.jpg)

This zoom on the electrods I put on my forehead. 

[![enter image description here](https://i.stack.imgur.com/WghSk.jpg)](https://i.stack.imgur.com/WghSk.jpg)

And this for the signal electrods I put on my front head.

[![enter image description here](https://i.stack.imgur.com/Kt0OP.jpg)](https://i.stack.imgur.com/Kt0OP.jpg)

**Edit:**

As a sensor, the solid gel electrodes have high input impedance and low output impedance: what this essentially means is that current can easily pass through downstream to the rest of the circuit (low output impedance) but would have troubling passing upstream back to my temples (high input impedance). This prevents the user from being injured by any high currents or voltages in the rest of my circuit; in fact, many systems have something called a patient protection resistor for additional protection, just in case.
Many different electrode types exist. Most people suggest Ag/AgCl solid gel electrodes for use in EKG/EOG/etc applications. With this in mind, you need to look up the source resistance of these electrodes and match it to the noise resistance (noise voltage in V/sqrt(Hz) divided by noise current in A/sqrt(Hz) -- of my op amps -- that is how i choose the correct instrumentation amp for my device. This is called noise matching, and explanations of why matching source resistance Rs to noise resistance Rn works can be found online like [here](https://www.maximintegrated.com/en/app-notes/index.mvp/id/3169). For my INA111 that I chose **And i replaced with lm324cd**, the Rn can be calculated using the noise voltage and noise current of the data sheet like:

[![enter image description here](https://i.stack.imgur.com/fWCWQ.jpg)](https://i.stack.imgur.com/fWCWQ.jpg)

**A possible specific question:**

Can I replace LNA11 amp with any other amp? if yes what should I change in my circular ?