See simple Infrared Intruder Alarm circuit. Even it is best. But it is a good teacher to learn electronics. Using infra-red system.
All controller, motor speed driver,switches,timer,sensor,and more : Timer switches • DC motor speed control • Delay timers • Light switchs • SCR controls • Light dimmers • Infrared remote control system • and more…
SEE DIY compressor time delay circuit. Protect your compressor when power outage and Electrical fluctuations. Using normal parts and cheap.
You finish PWM signal with Arduino control solenoid valve. You should use solenoid coil driver circuit. Good choice. 2 MOSFET and a few parts
Simple Key code lock switch circuit using IC-4017 digital, uses 10 switch bottom to control output by Relay. No microcontroller so easier and cheaper!