Mobile Setup - Circuit coming on with the igntion?

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alphamike
Posts: 112
Joined: Fri Aug 15, 2008 7:51 pm

Mobile Setup - Circuit coming on with the igntion?

Post by alphamike » Sun Jul 05, 2009 3:02 pm

I've been through the days of tapping into the cigarette lighter or radio circuit to power things. But over time i've learnt things and now know this is dangerous and gets messy.
I currently have a circuit running directly from the battery. But how i do i create one that comes on with the igniton, like the radio and eveything when the key is in the accesories position.

Regards,
Alex

Longreach
Posts: 1085
Joined: Mon Aug 25, 2008 7:38 pm
Location: Goulburn NSW

Re: Mobile Setup - Circuit coming on with the igntion?

Post by Longreach » Sun Jul 05, 2009 9:48 pm

hi alex, go behind the dash and find the cigarette lighter positive feed (this is assuming that the cigarette lighter is switched by the key). solder a wire from it. go to your friendly auto parts store and buy a 30-40 amp accesory relay(same as you would buy for driving lights etc).
mount your relay somewhere easy to get at(trust me nothing worse than trying to diagnose in a tight spot). run your wire from your ciggie lighter positive wire to your realy and connect to terminal 86 on relay. dont stress about current draw relay coil only draws 30milliamps.
run your batt feed from positive of battery via a fuse (fuse to be 3-6in from positive batt terminal) to terminal 30 of relay.
run a wire from terminal 85 of your relay to a good earth point on the chassis of the vehicle(your batt neg goes to a bolt near the battery on the chassis), even use the same screw your using to mount your relay with.
run the wire from your 87 terminal to the radio your powering up.
dependent on the radio fuse size (10-15-20amp etc) run the fuse near your battery maybe a couple of amp higher in rating to allow for loss. the main reason for your fuse near the battery is to protect the wiring from the battery from shorts to chassis so you dont have a fire should the wire get cut. get a blade fuse holder as your car most probably runs the same sort of fuse (even mini blade fuse in the real late model stuff).
see how you go with that should work well.
ive used the ciggie lighter feed as its usually easy to get as and usually has a circuit to itself apart from the car radio.
cheers
VK2MRC

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