Switchable 12V supply

adriandilly · 20 October 2011 at 6:48PM

I've thought about making a latch switch circuit for the cigar lighter supply in my 2002 Focus Ghia 2.0l.

I want to put in a relay so the supply must be activated with the press of a button, so then when i turn the ignition off, the supply goes off. That way I can leave an FM transmitter or another device plugged in all the time.
My questions are:
- Can you get buttons in the shape of the heated windscreen/ heated rear window buttons to go opposite? Also, the blanking plate where I'm thinking of putting the button has slots in.. is this just a blanking plate or some sort of temperature sensor for the climate control?
-Could I take an ignition-switched cable from the back of the radio for the relay?
-Would it be easier to run an ignition-switched feed from the fusebox straight to the cigar lighter instead, and is there space for a new fuse?
-Am i wasting my time? lol

TIA

Gloomendoom · 20 October 2011 at 7:35PM

It would probably be easier to run an ignition switched supply straight to the cigarette lighter. Quite a few cars are wired up that way as standard. It's usually a 10 amp supply though IIRC

I know nothing about Ford Focuseses but on some cars it is possible to customise the settings so the cigarette lighter is either ignition switched or not, depending on the owner's preference.