designing a 12v interceptor circuit/relay

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Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=91381
Printed Date: May 13, 2025 at 9:37 PM

Topic: designing a 12v interceptor circuit/relay

Posted By: m_pugliese
Subject: designing a 12v interceptor circuit/relay
Date Posted: March 07, 2007 at 3:01 PM

OK, I'm trying to figure out a way to Open a normally Closed circuit using a 12V source to open the light circuit. The light has to work except for when I do not want it to (the momentary switch). The way I have to set this up is for me to supply 12V to either a set of relays (which I have little experience with) or a circuit. Basically, here's a vague run down of what I'm trying to do. Someone who knows relays may be able to help me on this. This design would have some great uses for people working on their cars.

Here's a vague work scratch for what I'm trying to do. Any help would be greatly appreciated.

posted_image

Replies:

Posted By: Hymer
Date Posted: March 07, 2007 at 4:11 PM

a standard 5 pin bosch relay will do what ya want

pin 85 to momentary (12v whn switch closes)
pin 86 to ground
pin 30 to 12v
pin 87a to the input of the lite
pin 87 to???

when the relay gets 12v from your switch it will flip the 87a contact to 87 [turning off the lite] and supplying 12v to pin 87 of the relay [for whatever purose you want...

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Tire Proz Stillwater Mn
High End Restyling and Comlete Repair

Posted By: m_pugliese
Date Posted: March 07, 2007 at 7:16 PM

Thanks. I figured a relay would work, but like I said...I Don't Know Jack About Relays!
Thanks a ton! posted_image