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verify cold cathode light relay diagram?

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=100744
Printed Date: June 26, 2025 at 5:02 PM


Topic: verify cold cathode light relay diagram?

Posted By: passions
Subject: verify cold cathode light relay diagram?
Date Posted: January 04, 2008 at 12:40 PM

This is my diagram to have a cold cathode light turn on automatically when I open the trunk (trunk light coming on). I also have a SPST switch to disable the relay whenever I don't feel like having such a bright light.

I'm grabbing 12v power from the trunk light fuse with an Add-A-Circuit device. Once the trunk light turns on, the relay goes active. I also have a 3A fuse for the cold cathode, I'm not sure if that is really necessary though (trunk light has a 7.5A fuse already..)

posted_image

I'm pretty sure that everything is correct, but maybe I'm missing something.

Thanks!!





Replies:

Posted By: hotwaterwizard
Date Posted: January 06, 2008 at 1:15 AM

Why is the switch Grounded on the right side terminal of the switch?

Why use a relay if the wire will handle the current.

The power source is the same as the original bulb.

If you use a relay it is suppose to switch large current from a different power source like the Battery.



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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !




Posted By: passions
Date Posted: January 06, 2008 at 2:05 AM
It's a lighted switch, the ground is for the lighted part.

Hmmm...I'm using a relay because even though the wire can handle the current, I would like both stock bulb and new cathode to light up. Then if I turn off the spst switch, only the stock bulb turns on.

I think the power source being the stock bulb might be bad though. I'll try working on it more.

Thanks!




Posted By: passions
Date Posted: January 07, 2008 at 7:54 PM
Hey, you're absolutely right.

I don't need a relay! The cold cathode uses 12V @ 700mA, so I can just use a T-tap into the trunk light. Low enough amps. Mannnn...all this diagram for nothing! Heh.

Thanks.




Posted By: hotwaterwizard
Date Posted: January 07, 2008 at 8:33 PM

Well you asked the right questions and got an easy answer. Better to draw a little picture than to wire it all up and find out all your wires were not needed.

posted_imageLOL

The only dumb question is the one you didn't ask.



-------------
John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !





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