Relay help
Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=3514
Printed Date: May 23, 2024 at 9:54 AM
Topic: Relay help
Posted By: vinh766
Subject: Relay help
Date Posted: September 10, 2002 at 6:53 PM
im not familiar w/ relays, so please bare with me. i need a relay that has a basic input and output that should flow normally, but when another power source is added through another input, the output of the original stops it feed. is there a particular relay like that? or can someone just tell me some way to make one? hope that was clear enough, thank you. vinh766
Replies:
Posted By: go2pac
Date Posted: September 10, 2002 at 9:17 PM
If possible, could you give a more info on what you want to do? Is your primary source a + or - and if the secondary is + or -? Are you saying you want the secondary source to just interupt the first source but not have the secondary source go through the output? ------------- Karl
Pacific Accessory Corporation
Mobile Audio Interfacing Equipment
Connecting You to Your Music Since 1976
Posted By: vinh766
Date Posted: September 11, 2002 at 12:20 AM
my primary source is +, my secondary source would be + also, what i want is for the secondary source to interupt the output (primary source) or to make it - (negative) hope that was clearer then before, thanks for ur help go2pac vinh766
Posted By: vinh766
Date Posted: September 11, 2002 at 8:48 AM
an could you also tell me where i can get one of these relays? i've looked everywhere, but can't seem to find them. i tried radio shack, and they have these relays with tiny little pins, how do i connect wires to that? or is that not the right one? or do i need special connectors? thank you again
Posted By: joyride2k
Date Posted: September 11, 2002 at 9:47 AM
When you want to interupt the original feed, do you just want it to open the circuit or to actually send it a ground?
Posted By: vinh766
Date Posted: September 11, 2002 at 1:24 PM
when i interupt it w/ the feed, i want it to open the circuit (not quite sure exactly what open circuit means) but i want it to send absolutly nothing, as if it had no power what so ever. thank you
Posted By: vinh766
Date Posted: September 11, 2002 at 1:49 PM
there is another complication that i need to ask. when there is no feed from the primary, and there is a secondary feed, then i want the output to have a positive feed. so basically, this might make it easier, when the primary and secondary are BOTH feeding, then i want no output, BUT when ONLY ONE feeds, then i want an output feed, no matter secondary or primary. is there a special relay for this? or can i use a SPDT relay and wire it a certain way or something? one more thing, where can i get basic relays (like the ones in the site) or the ones i need. like what kind of stores? home depot? circuit city? Radio Shack?
Posted By: joyride2k
Date Posted: September 11, 2002 at 2:44 PM
You can do this with two SPDT relays:
One of the relays will reverse the polarity of one of the feeds, for demonstration lets use feed 2:
86 - + feed 2
85 - ground
87 - ground
87a - not used
30 - pin 85 on the other relay
This second relay will actually function as the "switch":
85 - pin 30 of first relay
86 - + feed 1
87 - not used
87a - 12V+
30 - output to what you want to send the 12+ to
This way when feed 1 has 12V+ going through it, and 2 has nothing you can output 12V+ to what needs it. When feed 1 has nothing and feed 2 has 12V+, you get the same result. But when both have 12V+ going through them, you'll energize the coil in the "switch" relay and in turn will open the circuit (no output)
You can probably get relays at an auto parts store, or definately at a car audio shop.
Hope this helps.
Posted By: vinh766
Date Posted: September 11, 2002 at 7:57 PM
that information sorta help. when both feeds are at rest, that means that the ouput is energized though, when both feeds are at rest, i want the output to be at rest also. sorry for the complications. thank you so much so far
Posted By: vinh766
Date Posted: September 11, 2002 at 8:32 PM
omg, i just total had a light hit me, you don't have to help me anymore, thanks anyways though. just spent 3 hours in psychology class staring at 2 relays, and i just realized how to do it now, thanks anyways. you were a lot of help
Posted By: joyride2k
Date Posted: September 11, 2002 at 8:36 PM
You can add another relay and two diodes:
85 - ground
86 - diode isolate your two initial + feeds and connect them to this pin
30 - 12V+
87 - 87a of your "switch" relay
87a - not used
I'm pretty sure this solves the problem.
Posted By: go2pac
Date Posted: September 11, 2002 at 9:46 PM
------------- Karl
Pacific Accessory Corporation
Mobile Audio Interfacing Equipment
Connecting You to Your Music Since 1976
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