trigger relay from two different sources

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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=131307
Printed Date: May 12, 2025 at 4:40 AM

Topic: trigger relay from two different sources

Posted By: hudd4473
Subject: trigger relay from two different sources
Date Posted: April 29, 2012 at 10:22 AM

I currently have a relay for an aux fuse block triggered by the ign(+)...I want to be able to hook a rocker switch so i can trigger the relay w/ the ign off but i dont want it to backfeed and power everything on that side of the ign switch...what diode would i use? or is there some other way to do this?

Replies:

Posted By: howie ll
Date Posted: April 29, 2012 at 10:52 AM

Wire each wire to 86 on the relay with inline diodes, see diagram:-
2_source_relay.bmp

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Read the installation manual, do a search here or online for your vehicle wiring before posting.

Posted By: hudd4473
Date Posted: April 29, 2012 at 12:41 PM

thats exactly how i want to do it but what diodes should i use....do you know a part or model number seems like a bunch of different ones out there...thanks for the help

Posted By: kreg357
Date Posted: April 29, 2012 at 1:10 PM

Use 1N4004 diodes as long as the relay coil is the only current draw ( as per Howards diagram ). Available at RadioShack, etc.

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Soldering is fun!

Posted By: i am an idiot
Date Posted: April 29, 2012 at 5:57 PM

1N4001 thru 1N4007

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