Relay and 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=69311
Printed Date: May 15, 2024 at 11:51 AM

Topic: Relay and switch?

Posted By: aaron19121
Subject: Relay and switch?
Date Posted: December 27, 2005 at 3:14 PM

I have a magnetic reed switch as a kill switch in my car i was told that i should run the switch through a relay or the switch may fail. how would i do this????

Replies:

Posted By: KPierson
Date Posted: December 27, 2005 at 7:06 PM

Run the reed switch in series with the coil of the relay (pins 85 and 86).

Then, wire the contacts of the relay like you would any other switch.

With more information it would be easier to help you.

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Kevin Pierson

Posted By: techguy688
Date Posted: December 27, 2005 at 7:20 PM

Using a Bosch style Relay like on https://www.the12volt.com/relays/relays.asp

Cut the wire and take the +12 vdc side of the wire and connect it to the 30 post.
The wire that goes to the ignition(the other side of the cut wire) connect to post 87a ( Normally Closed). The circuit will work like normal with this connection. Connect post 86 to a good chassis ground. Connect a wire to post 85. Connect your reed switch to that wire and on the other side of the reed switch, connect that to 12 vdc. A drawing would make more sense posted_image

This will interupt the circuit only when a magnet is near the reed switch. Good Luck

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Just because you've done something for a long time doesn't mean you're any good at it.
Cable Ties Rock!

Posted By: aaron19121
Date Posted: December 27, 2005 at 8:13 PM

if you could come up with some type of drawing the would be great.

Posted By: techguy688
Date Posted: December 27, 2005 at 10:07 PM

There are several relay diagrams on this site like https://www.the12volt.com/relays/page2.asp#sk2

Here is a modified version. Check out the relay section of this site under basic on the top left of the screen for more good relay info

posted_image

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Just because you've done something for a long time doesn't mean you're any good at it.
Cable Ties Rock!

Posted By: aaron19121
Date Posted: December 28, 2005 at 10:33 AM

Posted By: aaron19121
Date Posted: December 28, 2005 at 10:56 AM

sorry just thought about it and it would not work.

Posted By: techguy688
Date Posted: December 31, 2005 at 5:22 PM

you almost have it. Connect 12vdc constant power to the 86 post. You make also want to protect the 87 post from accidentally grounding...

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Just because you've done something for a long time doesn't mean you're any good at it.
Cable Ties Rock!

Posted By: aaron19121
Date Posted: December 31, 2005 at 10:34 PM

i probaly would understand it better if i uderstood more how a relay works. i have to read some more. So when you put 12volts to 86 the relay is pulled open and when you ground # 85 THE REED SWITCH it closes to make the connection. Correct

Posted By: techguy688
Date Posted: January 02, 2006 at 9:21 AM

Connecting 12 volts to 86 doesnt complete the circuit. The circuit will be complete when the reed switch is closed( when you put a magnet near it)and there is 12vdc to the 86 post, and there is chassis ground on the other side of the closed reed switch .
When this circuit is complete, it energizes the coil and connects 30 (Common) to the 87 (Normally Open). This also Diconnects 30 from 87a (Normally Closed)

A relay is two seperate circuits. posts 85 and 86 are one circuit. Posts 30, 87, and 87a are seperate circuit. The 12vdc from 86 and 85 dont provide power to 30,87, and 87a

I hope this helps a little bit.

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Just because you've done something for a long time doesn't mean you're any good at it.
Cable Ties Rock!