relay that triggers when ground is broken
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=115611
Printed Date: May 12, 2024 at 12:23 AM
Topic: relay that triggers when ground is broken
Posted By: floorboy
Subject: relay that triggers when ground is broken
Date Posted: August 11, 2009 at 11:32 PM
Hi. New guy here. Sorry if this has been asked already.
I am trying to make an alarm of sorts and need a relay that will trigger when a ground is broken. Will not be a lot of load on it. just some lights and a horn flashing. thanks
Replies:
Posted By: skwearl
Date Posted: August 12, 2009 at 12:41 PM
hook up a relay as follows: 86 12v 85 ground(your trigger wire) 87a 12v power feed wire 30 power output wire
Posted By: floorboy
Date Posted: August 12, 2009 at 4:22 PM
Thank you I will try that. I am not an electrician by any means and I hope I explained it right.
Posted By: floorboy
Date Posted: August 12, 2009 at 5:41 PM
Ok, so what I am trying is working so far..... now, as I understand, In order to get multiple triggers can I splice in multiple wires into the ground using diodes? Or would I have to use more relays?
Posted By: i am an idiot
Date Posted: August 12, 2009 at 6:32 PM
The relay is going to be energized until the ground is broken. If you use a standard Bosch/Now Tyco relay, it will draw 160 Miilliamps constantly. If you drive the car every day you may be OK. If you leave the car parked for 2 or more days, it will drain the battery. Radio Shack sells a 12 volt relay that draws around 40 Milliamps. I would look into that if you are still wanting to try this.
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Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB
Posted By: floorboy
Date Posted: August 12, 2009 at 6:52 PM
Ok I understand... this is mainly for my boat when I am on the road in a strange town overnight with it.
Posted By: floorboy
Date Posted: August 12, 2009 at 11:33 PM
Do you have a part number or a link to the radio shack relay?
Posted By: i am an idiot
Date Posted: August 13, 2009 at 4:19 AM
https://www.radioshack.com/product/index.jsp?productid=2062482 This relay is not numbered or layed out as described earlier. You need to use the 2 coil connections to trigger the relay. And for your lights and sirens, apply power to the Common connection. Connect the lights and siren to the Normally Closed connection. ------------- Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB
Posted By: dualsport
Date Posted: August 15, 2009 at 5:59 AM
Use a transistor such as a MOSFET instead of a relay to do the signal inverting and you can essentially eliminate standby battery drain.
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