Negative Trigger Relay Backfeeding Problem
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=123031
Printed Date: April 29, 2024 at 2:21 AM
Topic: Negative Trigger Relay Backfeeding Problem
Posted By: 25thhawk
Subject: Negative Trigger Relay Backfeeding Problem
Date Posted: August 08, 2010 at 4:39 PM
I have a neg trigger relay wired up with 30+86 going to 12v, 87 output, 86 to the neg trigger. My problem is that it is backfeeding 12v of current to the trigger wire when the trigger wire is open. This is then burning up the device on the other end of the wire. How can I stop it from backfeeding? If I use a diode on the neg trigger wire will it still switch the relay? Thanks
Ryan
Replies:
Posted By: abethebue
Date Posted: August 08, 2010 at 4:58 PM
what are you trying to accomplish with these relays
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abethebue
Posted By: icearrow6
Date Posted: August 08, 2010 at 5:27 PM
Yes a diode on the neg trigger wire will keep positive from feeding through the wire.
DIODES Explained-------------
Posted By: howie ll
Date Posted: August 08, 2010 at 5:55 PM
First you mean 85 as the neg trigger the alternative is a diode soldered across the coil terminals, 1N4004 with the band towards 86 (+) and plain end towards 85(-).
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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: i am an idiot
Date Posted: August 08, 2010 at 6:57 PM
Any negative trigger wire has 12 volts on it when the door is closed. Yes a diode will stop the 12 volts from getting to the device. However, I think that the backlash from the relay is what is taking your device out. Howie's solution is more than likely going to take care of your problem.
Posted By: 25thhawk
Date Posted: August 08, 2010 at 8:29 PM
Thanks guys. Yes I meant neg. trigger on the 85 sorry. These devices have nothing to do with traditional car electronics. More of race only pieces that's why I didn't give many details. So the soldering on the diode fix. I just solder it onto the terminals on the outside of the relay and then hook the wires to the terminals? Thanks
Ryan
Posted By: dualsport
Date Posted: August 15, 2010 at 11:32 AM
You can attach diode right at the relay coil inputs, then wire it as you did before.
Just connect it so that the end of the diode with the stripe on it is at the +12V side. The diode limits the large voltage spike that's produced by the coil when you try to turn the relay off, which is probably what's destroying your driver.
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