the problem is, that my alarm has only 1 output (-12v) , wich is designed to connect an LED and place it on the dushboard ( so that when it's armed the LED lights up , and when disarmed turns off. i'm trying to use that -12v signal to conect to the central locking, some how.... i need to build some sort of circuit wich will triger a 1second pulse when the -12v signal ( from the alarm ) is sent, and a 1sec pulse when the -12 signal is shut off...
please find attached drawing