ISOx16 Relay. Am I stupid?

OK guys, this should be REALLY simple.

I have a multimeter connected to the outside pins of Relay1 (see photo).

This code should enable the relay, and I should see a complete circuit, right?

    void ProgramStarted()

Nothing. No click. Nothing.

I have done the dumb stuff. I’ve checked that the code breaks on that line and executes with no errors. I’ve tried other modules such as buttons and sensors. All work fine. I’ve even bought a new relay board. I’ve switched out the cables. I can’t get anything out of this module.

Please, someone tell me what I dope I am!


Did you provide the power for the relays?

Did you try using the center connection rather than the two outside connections? I don’t own one by my guess is the the center connection is connected to one of the two pins on either side depending on the commanded state. The outside pins are never connected (to each other) by the relay.

So, the multimeter reads positive connected to the center and one of the outsides. I am assuming that the relay is thrown open to the two outsides when enabled, and then back to the closed state when disabled.

I think after reading this ( I need to connect DC power from the IDE connector’s power to the relays somehow, although why would the unit ship requiring me to do a bunch of wiring just to use it for the only thing it can be used for?

Am I right? Do I need to provide DC power somehow to the relays? If so, how?


Not usually, the common connection is usually the center one. If you set it up again so you have a reading, when you change the relay’s state the needle will go to infinity. But as Architect has noted you probably need to add some external power to that terminal block on the end as well.

I have the relay connected to a Spider FEZ board via USB, so it should be getting USB power from that. See the photo for how it connects.

That will power the module, but not the relays. That blue terminal block, with two screw terminals, is where you need to provide the power that you are switching with the relays.

Ah… I thought that was just a ground. So that should be 30v DC?

What are you using it for? What are you switching?

I’ll be switching on 110V AC outlets.

Working voltage is: 12 VDC

Switching voltages are according with the spec:

I see. So the power that flows through the board also powers the relays.

Did not understand that.

Thank you

Hold on

I am not sure about those terminals actually. Need a second opinion here.

It should be 12V DC on these terminals to power the Relays.

OK. Are there any amperage concerns? I can’t figure that out from the schematic

Ok to power the relays you need 12VDC on the two terminals that stand out separately.

And relays are capable of switching:

250VAC,10A or 30VDC,10A

There’s 3 voltages in play here, which makes this thing complex to use. There’s the voltage that’s running the ICs and switching the transistors, and those transistors are switching the 12VDC, and that voltage is switching the relays, which can be switching higher voltages.

I have one, and it’s still in its bubble wrap, for that reason. I found that for my purposes, tiny little signal relays are quite perfect. They are switchable directly from an MCU pin (10mA current draw), have built-in limiting resistors, and built-in back-EMF diodes. Very slick, for ~$1.5 per, if you’re switching low voltages (24VAC in my case).

My electrician says the schematic says to run a double ground from those two terminals. Is he full of s*%t?

@ godefroi - That sounds like a nice relay. I don’t think I’ve run across them. Can you provide a link?