hooking diodes across relay leads

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=35040
Printed Date: May 11, 2025 at 7:46 AM

Topic: hooking diodes across relay leads

Posted By: morebassplease
Subject: hooking diodes across relay leads
Date Posted: July 04, 2004 at 3:11 PM

i use a lot of relays in my car to power neons, strobes, and other fun stuff. i've read that u should hook a diode across the leads (no idea which ones). i know how a diode works but why would i need it and which type of diode do i use, or are they all the same and any would work fine? thanks.

Replies:

Posted By: defective
Date Posted: July 04, 2004 at 5:15 PM

https://www.the12volt.com/relays/relays.asp

just read this... it explians

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Posted By: HotRod53F100
Date Posted: July 06, 2004 at 8:53 PM

Remember the little hand shockers or the old tinfoil on the edge of a book with a battery inside trick? Maybe I'm dating myself..LOL These both worked on the principal that a diode across a contact eliminates. A diode eliminates the "inductive kickback" that would weld a relay contact or blast a sensative unit. A colapsing field has nowhere to go when disconnected and it generates a kickback many times higher than what you were drawing. You will also see a device called a "transorb" which does the same thing.