Digsy
09-10-05, 23:35
Quick general question to save me ripping my dash apart just to do some testing: Can anyone tell me whether a head unit's aerial signal wire (usually blue) goes from 0V to +12V when the head unit is swiched on, or from +12V to 0V? Or even from floating to +12V or 0V
I want to make up a relay box to sever the head unit from my speakers to eliminate the annoying thump at power off that I can't seem to cure. I am going to use the aerial signal to switch the relays via a transistor, but for the techy minded I need to knoe whether I need an NPN or a PNP transistor, hence the question.
Finally, a question for the real electrical eggheads: Can anyone suggest a suitable diode to put accross the relay cois for back-EMF protection?
TIA.
I want to make up a relay box to sever the head unit from my speakers to eliminate the annoying thump at power off that I can't seem to cure. I am going to use the aerial signal to switch the relays via a transistor, but for the techy minded I need to knoe whether I need an NPN or a PNP transistor, hence the question.
Finally, a question for the real electrical eggheads: Can anyone suggest a suitable diode to put accross the relay cois for back-EMF protection?
TIA.