So I built an aquarium dosing system prototype that uses a particle photon and their 4 channel relay board. Currently Particle doesn't offer a MOSFET switch board, so I decided to build one that also seats the Photon board. There are two things I need to add that I'm not sure how to go about adding, one is an optoisolator, and the other is a switching voltage regulator so I can use the main power input to power both the motors as well as the Photon. The motors will most likely be 12v, but the photon is 5v. Essentially I've never worked with either of those components so I'm not sure where to begin.
I've attached a copy of my fritz so you can take a look. This is my first time with any PCB development so if you have any advice please let me know.
***UPDATE: After further researching the circuit for a quality switching voltage circuit, I've come to realize that it might be easier to purchase a dual output Mean Well switching power supply. The only way it would be efficient would if I ordered the boards with the circuit pre-soldered with SMD components. If you have any insights please let me know.
photon_MOSFET_schem.fzz (26.0 KB)