Relay Instead of DPDT Switch?

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=138956
Printed Date: May 09, 2025 at 3:47 AM

Topic: Relay Instead of DPDT Switch?

Posted By: Jweb
Subject: Relay Instead of DPDT Switch?
Date Posted: May 11, 2015 at 3:44 PM

For some reason my brain won't wrap around this application. I wired into a GM head unit to tap into the CD player input in order to run a MP3 player or ipod. I was going to just wire a mini DPDT switch to change the input from the normal CD player input to the MP3 input that goes to a 3.5mm jack. I was hoping someone here could help me diagram a relay to switch the input depending on which one had a signal. Is this easy or hard to do? Thanks for any help.

Replies:

Posted By: hotwaterwizard
Date Posted: May 19, 2015 at 7:24 PM

Most are Grounded so it is easy. You must mount into a Metal Grounded Box to eliminate humm and Motor noise. posted_image

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

Posted By: howie ll
Date Posted: May 20, 2015 at 5:52 AM

The above is best but if you want to use a relay, you need a voltage output from either iPod or MP3 and good luck with that!
The voltage output, probably 5 volts will trigger a DPDT relay with a 5 volt coil.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Posted By: Jweb
Date Posted: May 20, 2015 at 9:48 AM

I already wired the switch but thanks for this. I don't think I'd be able to get a trigger from either input.

Posted By: howie ll
Date Posted: May 20, 2015 at 9:49 AM

Yes it means opening one up and bench testing, best of luck on opening one of them. posted_image

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Posted By: hotwaterwizard
Date Posted: May 20, 2015 at 8:02 PM

I use an Audio Switcher on my amp because it does not have a aux power wire. It detects the audio signal input and provides 12v output to switch my amp on and off.

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