Can I use an SPST Relay instead of SPDT?

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=74402
Printed Date: May 12, 2025 at 8:46 PM

Topic: Can I use an SPST Relay instead of SPDT?

Posted By: rsantos97
Subject: Can I use an SPST Relay instead of SPDT?
Date Posted: March 13, 2006 at 11:28 AM

I need to use a Relay to change the polarity of the signal comming from the alarm (-) and going to the parking light (+), and I saw the diagrams on this site on using an SPDT Relay, but I wanted to know if I can use an SPST Relay instead cause that is what they have at RadioShack.

Thanks

Replies:

Posted By: Twelvoltz
Date Posted: March 13, 2006 at 11:31 AM

Yes you can, just make sure the relay can handle the load you are going to put it under.

Posted By: rsantos97
Date Posted: March 13, 2006 at 11:49 AM

The Relay I want to use is a 30Amp Auto Relay from Radioshack. The only difference that I see is that there is no 87a connection just 30, 85, 86, and 87.

Posted By: Twelvoltz
Date Posted: March 13, 2006 at 11:52 AM

Yup, exactly what you need. It may be cheaper to purchase a SPDT from a local installer though.

Posted By: rsantos97
Date Posted: March 14, 2006 at 1:27 AM

Thank you very much for your quick replies.

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