Mini Relay vs Automotive Relay

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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=57669
Printed Date: May 09, 2025 at 6:38 PM

Topic: Mini Relay vs Automotive Relay

Posted By: chicagohh
Subject: Mini Relay vs Automotive Relay
Date Posted: June 14, 2005 at 10:34 AM

I have a 12VDC mini relay from Radio Shack - part 275-248 (5 terminal). I would like to see if I can use it for a project instead of the Bosche type automotive relay that I currently use.

The terminals are not in the same positions as the automotive relay and I keep making sparks with my lame experiments.

Here is the layout of the mini-relay -

posted_image

Which terminal are which?
30 = ?
87a = ?
87 = ?
85 = ?
86 = ?

Thanks,

Joe

Replies:

Posted By: Mad Scientists
Date Posted: June 14, 2005 at 4:28 PM

Using an ohmmeter, probe around until you find two pins that have a resistance of about 400 ohms. This is your coil

Of the remaining three terminals, you should find two are connected together without powering the coil, and the remaining terminal should be connected to one of the previous terminals (NOT the coil terminals) when the coil is energized.

Helpful?

Jim

Posted By: chicagohh
Date Posted: June 14, 2005 at 5:12 PM

Very helpful.

Thanks Jim.

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