I have cats coming to my lawn and poop which is very annoying. I tried couple of methods to stop them but to no avail. I am planning to use an old 12 Volts DC transformer from an old printer and connect the negative and the positive to two bare and horizontal wires 6 inches apart, making it like a 6" 2-wire fence. When the cats comes to cross the "fence", it will get electrical shock. Any thought about the effectiveness of this setup? I believe the voltage is not enough to kill them which I don't mean to. Is that correct? Thanks.