Hello this is a real prototype for a project that I am working on. The machine needs to compress air and keep that air between 4-6 psi using this controller. The relay in this circuit is used to power a compressor that pumps air into the machines air tank. In the circuit i have replaced the tank with a capacitor in the bottom left corner. Although it stores charge rather than air it is analogous to an air tank with voltage rather than pressure. FYI all op-amps are in a single IC and are supplied with 12V and 0V. If you have any questions or concerns about the circuit please post below.
