Salty seadog
Space Cadet...(3rd Class...)
It rather depends on the "Clever Stuff". Please pay attention!
@classic33: The "no name" solenoid valve cost less than £8 inc shipping. I like 12v DC because it's a convenient one for cobbled-together control circuits if they are not low-level logic ones. Clunky will do for cats.
I think I'm a slave to the system..... if I find a lump of cat sewage in the alley i just leave it there now and no more appears, if i clear it away another will appear.. my approach requires no stress and less guns.....