Some years ago I purchased an old compressor that has been a work horse. A year ago the mechanical pressure switch and contractor's gave out causing the compressor to no longer turn off despite trying to persuade it with a hammer.

I replaced the assembly at a cost of about $120.00 

The other day to my dismay the switch failed again, this time it will not turn the compressor on.

Rather than just replace the switching system again I decided to build a new one with some smarts and using an ESP8266, a pressure sensor and a solid state relay I have begun putting together and coding a smart switching system that connected to the local network.