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Control LED by car ignition.

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tim_l_012

New Member
Hi All,

i need a simple circuit to switch off a circuit when current is passed through it.

The 12v comes from the car battery, and I would nick 12v from the cigarette lighter/radio wire. The radio only comes on with the ignition.

i have a flashing LED setup, but I need it to turn off when the ignition is on.

If you could provide any help that would be excellent.

Thanks in advance, :)

Tim.
 

john1

Active Member
take its ground to the ignition.
that should do it.
 

tim_l_012

New Member
Hmm I don't understand that one..

I'm a bit of a beginner so you might have to explain a bit.

What do you mean?

Thanks in advance, :)
 

tim_l_012

New Member
My mate suggested something like a NPN transistor..

I have been looking around and a NAND gate seems like something simple.. are they hard to implement?

If so how would I connect them?

Thanks in advance, :)

Tim.
 

e

New Member
you can do it with a small relay as well, coil IGN and ground, NC -power to LED and common to supply
 

Eclipsed

New Member
I think what he meant was, on most vehicles the ignition is a ground when the key is off.So put a constant power to the positive side of the led and run the negative to the ignition, then the circuit is complete when the ignition is off.I would put another diode in there too, some of the vehicles power circuits could become a ground if a fuse blows, which would reverse the LED voltage.
 
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