-12v pulse???

[Oziam]

Hi,
I have a 12VDC SPDT relay, C is -12v, what I am trying to achieve is for the NC terminal(coil power off) to receive a -12v signal for a moment like a momentary switch or pulse then 0v.
I guess a CAP should sort it out but what is confusing me is the wire connected to NC is polarity changing, when the relay is ON it switches to +12v

 

[CDRIVE]

Is there any particular reason that you want to generate a pulse with a relay? It's, by far, not a good choice.