Here is a shot of my home made system from the back..

In this shot you can see the on off switch. When the system is turned on it will operate to the pressure you have dialed in on the pressure switch (funny thing with the lexan box on top of it.) The pressure switch then shuts off the pump and closes the check valve / solenoid. Once the pressure drops below a desired setting... the whole thing will kick back on and continue to operate until the desired setting has been reached again.

The the entire process starts over again - for as long as you leave the system 'on'.

The system has been tested and so far it looses about an inch of pressure for every three hours it is in use. Pretty respectable - I should track down the leak.... but it only cycles every 5 or 6 hours (give or take) so I am in no hurry.