I'm having an issue with connecting the industrial pneumatic valve with 2 coils to relays. EDIT: I have connected it like this in the scheme below. Coils are connected to NO port on the relay, controlled by an Arduino. Coils are standard MS 22 24VDC 3W. I have tried controlling one coil at a time, and it switched on and off as it should. Both of them. But when I connected both coils as on the scheme, there were problems... After one coil was set off there was a clicking sound and it came back on and looped in this cycle.
I measured some voltage on the valve housing when that happened. Don't really understand what is happening and I would like to get some help.

I have only one idea, to use 2 separate power supplies would that solve the problem? Is there anything else to do? SchemeRele spec

  • \$\begingroup\$ Show a schematic not a cartoon and provide data sheets for all modules other than the arduino. \$\endgroup\$
    – Andy aka
    Nov 16, 2020 at 14:54
  • \$\begingroup\$ Thank you for your answers. @Andyaka is this better? I'm quite new to this so my apologies... \$\endgroup\$ Nov 16, 2020 at 21:11
  • \$\begingroup\$ @jsotola thanks for noticing, it was a mistake in the scheme only. \$\endgroup\$ Nov 16, 2020 at 21:13

1 Answer 1



simulate this circuit – Schematic created using CircuitLab

Figure 1. A more readable form of the schematic.

Your approach is correct and it should be obvious from the redrawn schematic that you simply are switching two solenoids on in parallel as you would with your house lights.

I suggest monitoring the voltage at the power supply with one, the other and both on. It may be that the power supply is current limited and shutting down on over current. Update your question with a link to the 24 V power supply datasheet.

We usually refer to relay "contacts" rather than "ports".


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