Is there such a thing as a normally closed relay? I am looking for a relay that will actuate a 12V device when the power is turned off. I.e. When I turn off the ignition.

Essentially, I want to put one of those sweeping alarm LED's in the front windshield that will come on when the ACC Delay goes off to give the appearance of an alarm.

I really see no need to blow $150 on an alarm if I can make it LOOK like there is an alarm. The alarm is only a deterrent anyway, so I am thinking that the visual indicator in and of itself would be better than nothing.

 

There was a technical post somewhere on here that linked to a site where somebody defined all of the different types of relays. I think if you check in the how-to section...it may have been on the svtlightnings site.

To answer your question yes there is such a relay. It usually works with 2 devices and a single switch...when you turn the swich on it acvtivates the real to send power to one device, and when you turn it off it will send power back to the other...you would just need to see which is the power on acc'y feed, and which is the power off acc'y feed and go from there.

 

No need for a relay. The Accesory (or ignition) wire will show negative when the ignition is off. So hook up the negative to this, and the positive to a constant. When you shut off the ignition the wire will show negative, and start the scanner....I had mine running like this for a long time

Robbie