relay deactivates switch when power
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=135955
Printed Date: April 29, 2024 at 10:31 AM
Topic: relay deactivates switch when power
Posted By: tahoe45
Subject: relay deactivates switch when power
Date Posted: January 30, 2014 at 8:53 AM
Hey everyone,
is there a relay that exists that when there is power supplied to it. The Switch that is connected to it is inactive and then when you cut the power to the relay it is active? For an example I would like to wire up a switch to the negative wire of the door popper so the switch would complete the ground when pushed. I was thinking of running the acc power from my car to the relay. So in the end when the car is off the switch is active and when the key is in the ignition and turned to on the switch is inactive. Sorry if this is a confusing post, but any suggestions or help would be greatly appreciated.
Replies:
Posted By: oldspark
Date Posted: January 30, 2014 at 10:16 AM
SPDT relay.
IGN +12V to 86
GND 85
30 & 87a for the switch.
87a & 30 are NC = Normally Closed contacts with coil 86/85 de-energised.
With IGN on 30 & 87a open thereby disabling the switch.
Posted By: tahoe45
Date Posted: January 30, 2014 at 10:26 AM
Awesome. So will 30 and 87A be negative or positive?
Posted By: oldspark
Date Posted: January 30, 2014 at 4:49 PM
It doesn't matter. 30 & 87A are merely 'inserted' into whatever you want switched. In your case this is from your switch.
Because relay coils and contacts are independent (except for specialised types like 3-pin horn relays) it doesn't matter what voltage or polarity the contacts have.
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