Control LED by car ignition.

T

tim_l_012

New Member

• Jan 2, 2004

• #1

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.

 

J

john1

Active Member

• Jan 2, 2004

• #2

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

 

T

tim_l_012

New Member

• Jan 2, 2004

• #3

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,

 

T

tim_l_012

New Member

• Jan 2, 2004

• #4

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.

 

T

tim_l_012

New Member

• Jan 2, 2004

• #5

Just thinking back to a sort of similar post I had ages back, If i just remove the other LED, should this circuit in this post be ok?

Remembering that its 12v instead of 5v though, my LED can handle from 3v to 15v.

https://www.electro-tech-online.com/threads/solar-battery-charger.1320/

Thanks in advance,

 

E

e

New Member

• Jan 2, 2004

• #6

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

 

E

Eclipsed

New Member

• Jan 2, 2004

• #7

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.

 

seeker

New Member

• Jan 3, 2004

• #8

Hi Tim,
maybe try this
https://www.radioshack.com/product...._name=CTLG_011_006_002_000&product_id=276-308


Diode is 1n4001 or similar

 

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