[Petrol Head]

So, I was going through old boxes and found this:



It’s an air siren from an old Chapman aftermarket vehicle security system from the 1980s. My parents had this on their 1985 Buick Regals and when they went off it was LOUD. Think ambulance or fire truck siren but it does not go up and down - just up, like an air raid or tornado siren. They were set using a push-in lock under the dash that was also part of a cable that engaged a hood lock.

It works on straight 12 volts constant, and the way they used to be triggered long before cars had remote security systems or computers built in from the factory was they were connected to the dome light circuit and when it was set, if you opened the door and the dome light turned on the current draw tripped a relay which put 12 volts to the siren off the battery.

So I’m just curious if anyone knows if there is anything in the car that turns on a constant 12 volts when the alarm is tripped. Of course it sounds the horn but that’s a 12 volt pulsed on and off. This requires 12 volts constant.