When I was doing my electrical apprenticeship I had a very nice hatchback Torana.
Car alarms were piss easy to bypass back then so I made a more effective deterrent.
I built an independently powered inverter circuit switched by a touch switch that fed a high performance ignition coil, this was connected to the chassis of the car.
I cannot say for sure if it actually prevented anyone from stealing stuff from the car, but I do know it was effective for a few reasons. I occasionally forgot to turn it off before putting the keys in the door
and one incident that occurred while I enjoying a night out in town. I was in the club enjoying a few not so quiet drinks. Now this club had a hot dog vendor that used to set up in the car park. He sold damn good hot dogs too. Anyway, a mate of mine had gone out to wait in line for one when he noticed one bloke staggering up in between the parked cars. His interest was naturally aroused because the drunken fellow was heading in the general direction of my Torana, and knowing that is had "extra" protection, he thought this would be interesting.
The bloke finally reached his destination, but much to my mates' dismay he leaned against the car next door. What he didn't realise was he was making the necessary preparations to answer nature's call. The next thing he hears is much cursing and the drunk bloke looked as if he'd found a whole new reserve of energy! He jumped about evidentially trying to stop the flow. Somewhere in the confusion, he slipped over in his doings and emptied the remaining contents onto his own clothing. Last my mate saw was the guy running from the car park, tackle flying in the breeze covered in dirt, mud and urine. My mate had trouble standing at that point due to his laughter.
I reckon it's a fair bet that that guy will never piss on a car's wheel again in his life!
It turns out it was also an effective deterrent for parking fines too since about 5 months into it's use I received a visit from the local constabulary advising me that I had a couple of complaints from parking inspectors and that I would be best advised to remove the system. They did think it was the best deterrent system they'd ever seen though.
