As someone who holds an engineering degree but is sort of new to circuit design/ electronics, I'm probably not aware of the many conventions and techniques that a more experienced circuit designer would assume are obvious. I would like to learn to become a competent circuit designer, however, and I was wondering if you wouldn't mind taking a look at this simple circuit I designed to test a pair of sensors. The sensors operate at 27V which is why I use MOSFETS to interface between the microcontroller and the inputs/outputs. The relay is there because those pins provide 27V power to the sensors so it would need to provide more current than the mosfet could, and also as a fail safe.
Specifically what I am not sure about is if I should place more diodes / caps to protect the circuit and reduce the chances of problems/ malfunctions arising.. I have placed diodes and caps on the input power, and a diode across the relay coil, but that is basically it, and I am not too confident about my cap choices.
Also, any observations / recommendations regarding the circuit, or even ways to improve the schematic layout would be great!
Thanks in advance!
Thanks to all the help, I have updated a schematic with the changes. I have replaced the linear regulator with a switching regulator, added bypass caps, fixed the relay placement/ made it a 24V relay, double checked that components will meet current/ voltage specs, added series resistances to fets, added TVS diodes on inputs, added fuse / on/off switch, tweaked the input voltage divider. added caps on inputs, and I think that is it.