I'm trying to test the 5V version of the relay listed at the web address below.


I have tried applying 6V directly from a battery to pin 6 with ground connected to pin 7, also tried the same for pin 1 and 12, but I don't hear any switching. Checking the resistance between pins 3 and 5 (and 10 and 8) shows an open connection (many megaOhms on my multimeter).

Which coil should close the relay? 6/7 or 1/12? I can't tell from the diagram. And why isn't it latching? I'm certain this question demonstrates a fundamental lack of understanding about latching relays. Please help a novice. Thanks!!


photo of relay

  • \$\begingroup\$ I would guess you have other relay. Judging by the picture you are doing it right \$\endgroup\$
    – user76844
    Commented Nov 19, 2016 at 8:15
  • 1
    \$\begingroup\$ You should never see a connection between pins 3 and 5. Pin 4 is the common pin, and will connect to pin 3 in one state, and to pin 5 in the other. It is not clear to me which coil will move the contacts to which state. \$\endgroup\$ Commented Nov 19, 2016 at 8:24
  • 3
    \$\begingroup\$ The coils have polarity marked and shading to match the pins, so energising pins 6/7 should switch to 3/4 and 10/9 connected. \$\endgroup\$
    – Spoon
    Commented Nov 19, 2016 at 8:40
  • \$\begingroup\$ Thank you! This is extremely helpful! Looks like 9/8 and 4/5 are connected. Unfortunately, applying 5.7V across 6 and 7 does nothing to the relay. Do I need a short pulse rather than continuous application. \$\endgroup\$ Commented Nov 19, 2016 at 8:47
  • \$\begingroup\$ What is the part number written on the device? \$\endgroup\$
    – Andy aka
    Commented Nov 19, 2016 at 10:48

1 Answer 1


The black coil and contacts indicate the contact arrangement for the coil most recently energized, so if you've momentarily connected +5V to pin 6 and 0V to pin 7, you should measure continuity between pins 3 and 4, and between pins 9 and 10.

Then, if you momentarily connect +5V to pin 1 and 0V to pin 12, you should measure continuity between pins 4 and 5 and between pins 8 and 9.

Like this: enter image description here

  • \$\begingroup\$ This is all very helpful, but I still can't get the black coil position to engage. Does the impulse have to be a certain duration? I'm just touching 5V to pin 6 and 0 to pin 7. \$\endgroup\$ Commented Nov 19, 2016 at 9:01
  • \$\begingroup\$ @VictorVanHee: According to the data sheet the maximum operate time for either SET or RESET is 4 milliseconds, so the pulse should last at least that long. \$\endgroup\$
    – EM Fields
    Commented Nov 19, 2016 at 9:16
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    \$\begingroup\$ @VictorVanHee: Could it be that you're reading the relay's pinout from the wrong side? That is, for the through-hole version the view shown is from the bottom, while for the surface mount version it's shown from the top. \$\endgroup\$
    – EM Fields
    Commented Nov 19, 2016 at 9:31
  • \$\begingroup\$ I tried 4 ways, reversing +\- and using each coil in both ways. Nothing. \$\endgroup\$ Commented Nov 19, 2016 at 9:55
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    \$\begingroup\$ @VictorVanHee: Then there are only a few things left to check out before declaring "Bad Relay." 1. Is 5 volts getting to the relay? That is, a. is there a break or a high resistance in the wires between the power supply and the relay? b. Is the power supply putting out 5 volts? 2. How much current do the coils draw? 3. What's the resistance of the coils and does it correspond to the resistance given by the data sheet. 4. Is it really a 5 volt relay? Check the part number on the relay versus the part number on the data sheet to find out \$\endgroup\$
    – EM Fields
    Commented Nov 19, 2016 at 10:22

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