First off I'm new when it comes to connecting electronic circuits. I'm sorry in advance if this question sounds unworthy or irrelevant.

I'm building this project as a hobby, and I ran into a problem when connecting relays. This is the relay he has used in the video "8 channel relay control panel PLC relay 5V module", and this is what I have purchased:

And Output from Relay to irrigation pumpsOutput Side

My question is; in the output side of the relay, where does the power for the +ve and -ve for the pumps go? In the video he has used a 3 piece terminal block to connect the power.

I'm guessing that O is the output which takes in the pumps +ve. Which one of the two does the -ve go in? I'm using a DC pump so I need to be careful so that it won't short-circuit and fry my chip and the board.


You only need to connect 1 side of the power feed.


simulate this circuit – Schematic created using CircuitLab

The C O and P on the terminals stand for normally Closed, normally Open and presumable Pole. Where Pole is the common (on the left of the schematic). Normally Open is not connected to Pole when the relay's coil is not energized (upper right contact in the schematic connected to VE+) and normally closed is connected when the relay's coil is not energized (bottom right contact in the schematic).

You can double check that with a continuity tester (or a few bits of wire a lamp and a battery that can power it).

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  • \$\begingroup\$ @Ch33f you can click the check mark next to the answer to make this the accepted answer (and upvote once you have some more rep). \$\endgroup\$ – ratchet freak Aug 30 '17 at 20:57
  • \$\begingroup\$ So i connected all 8 Opens together and connected it to the 12V power supply adapter of the pump and from the same terminal (i.e. Open) I connected to the +ve side of the pump wire and then i weld the -ve side of the pump wire and the Power supply to Ground on a separate PCB (i'm suing separate pumps unlike the guy on the video). But if i'm putting 2 wires in a same terminal won't they get connected by default, Then how is this relay even of any use ? \$\endgroup\$ – Ch33f Aug 30 '17 at 21:21

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