I'm using a relay for the first time and am unsure if I'm interpreting the pin diagram given in the datasheet correctly:

enter image description here

I know a SPDT relay should have five pins:

NO (normally open)
NC (normally closed)
COM (where the power comes in)
Two coil pins (applying voltage across these activates the relay)

Here's my guess at what pins are which:

1   - COM
2,5 - Coil pins
3   - NO
4   - NC

That makes sense to me, but since I've never used a relay before I would really like to double check!


1 Answer 1


Yes, you are right.

Anyway if you have doubts:

  • connect ohmmeter/continuity tester between 1 and 4 - if it shows zero resistance then this is the NC pin
  • do the same for pin 1 and 3. You should get open circuit.
  • between any coil pin and switch you should get open circuit.

I always do that, because I get confused with datasheets - top/bottom view.

Apply voltage to pin 2 and 5. Do the same test again. It should show opposite results.

  • \$\begingroup\$ Am sure that you meant to type "Apply voltage to pin 2" and 5 (coil) :) \$\endgroup\$
    – Marla
    May 15, 2014 at 22:20

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