Looking for ideas for a cheap DIY car alarm

[alohaspirit]

Dont want or need a real car alarm

Just something something simple that makes noise when they open the door
(and/or move something)


I was thinking about a personal protection siren rigged to the door
so when they open the door past 6 inches it would go off
(they wouldnt be looking for the string at night + I could reach in and disarm it)
although id have to sprint to the parking lot as the thing is LOUD


but Im curious to hear your boobytrap ideas

[2000mc]

...how bout a relay, a switch and some wiring for being cheap...

tap into the interior lighting somewhere, run a wire out to somewhere on the exterior you could hide a switch to enable/disable, edge of the hood or under the front bumper or something. then from that switch to a relay, from the relay to the existing car horn.

interior lights come on = car horn

[alohaspirit]

i was thinking something external or low voltage

(since I frequently unhook the battery as a deterrant)

[2000mc]

car alarm decals on all windows near door handles

[alohaspirit]

if only decals made noise when you opened a door

[NiHaoMike]

An air horn rigged to activate seconds after a smaller alarm which is activated as soon as a door is opened without disabling it first.

[alohaspirit]

I think I found it

Motion Alarm

now to find a cheap one

(and when I say cheap, I mean free)

[Christ]

Gun, string.

Mount gun on dash, pointing at driver's window. Attach string to trigger, other end to door.

Make sure gun is loaded, and string is just long enough that you can't get into the car, but you can open the door about 5 inches without it going off, so you can disarm it if you know it's there.

Frankly, I believe that car alarms are like door locks. They keep honest people honest.

[alohaspirit]

I think Ill stick with the motion alarm

[Christ]

LOL, Well, I can't say I blame you.