I am having some problems with relays sticking. It seems that when the relays are off and they turn on everything is fine. But they will no longer turn off. They need a mild knock on the relay to turn off. Has this happened to anyone?

I am driving some lamps through the relays. About 80watts total @ 120Vac. Is this "normal"?

Should I use a diode on the contacts?

Thanks for any help.

I have 2 more expansions, but I am afraid to use them and "spoil" them as well. Everything seems simple enough, am I missing something?

Do they have to be perfectly "flat", they are leaning slightly to the side (nothing is holding the expansions except the pins themselves).

Could it be a bad batch of relays?

Also, can you try unplugging the load and seeing if the Relays still stick?
It should be safe to test your other Relay Expansions with no load as well.

When I say "leaning" I mean about 5 degrees from flat. I don't think that should affect the relays.

Does the direction matter?

Why does it say "IN" and "OUT" on the relay?

I just bought 10 more from the store, so I will have some extras soon.

@Jim-Esposito The part number and relay specs are mentioned in the Wiki article on the Relay Expansions.
And the datasheet can be found here.

Is IN and OUT important?

I have 3 relay expansion stacked. 2 work well. No problems. The load on those is either none or 120Vac (on one of the two relays). The three that have failed seem to be on 120Vac load.

In/Out shouldn't matter at all @Samuel-Mathieson. Is the physical stackup of the extra relay boards affecting how much they are plugged in?

The thing is the light (relay on/off) light turns on/off as expected, but the relay itself is stuck. The problem is not so much in the software, its in the hardware. The fact that it has happened for 3 expansions then makes me wonder if I got a bad batch.

Do I need to use a diode, or something else on the relay?

Your posts are unclear as to how many Relay Expansions you have that work and how many that do not, and in what configuration. When troubleshooting hardware issues, we require photos of your setup as we have outlined in our defective item policy and our forum guide post. Without photos, there is nothing we can do.

As @Jim-Esposito mentioned, IN/OUT do not matter as it is simply an open or closed connection, but they can be useful when examining your circuits to see which wires are going where.

Short of a circuit design problem or defective parts (I am not yet convinced of either, just trying to chime in to help), another area you can turn your attention to, to try to solve the problem, is to see if the stuff is physically making contact for all the signals.

If you have an intermittent connection, something like what you are seeing is possible.

The problem with the lights expansion occurs no matter if it is on top or on the bottom. Tried 2 others as well. I will try 2 others I have later on tonight and hope that it solves the issue.

• If you've already done the trouble-shooting of moving the expansions around and they still stick, I think that rules out the possibilities I suggested.
• I don't think this is the cause of any of your troubles, but for this installation you may want to consider printing out a 3D case for the Omega and dock, at least to keep some of the stuff from getting dust and dirt on them. I don't have the link handy, but I did get one of the cases I found online printed recently, and the fit was near-perfect first shot. I wound up not needing the top portion, but if I did it would've needed just a bit of tweaking to allow the relay expansion to sit nicely.

Thanks. The dust will be removed. The case is a plastic case I bought specifically for storing the omega and the other bits and bobs. I used silicone to stick the Omega to the plastic case. Either way. Thats 3 relays that don't work. I wonder if perhaps I got a bad batch. I bought another 10 today so I hope that these will not have problems. I will test with another 2 relay expansions I have today. See what happens.

Normal suggestions to minimise this micro-welding are:

• Try driving the relay with a higher current so the relay operates faster closes faster to reduce possible arcing time - though I don't see how this could be done with the Relay Expansion
• Use a relay with a stronger return spring so it opens faster to again reduce arcing time - again not possible on the Relay Expansion without physically replacing the relays
• Use some suppression across the contacts to reduce the arcing - e.g. connect a capacitor across the contacts (i.e. from the In to OUT connections) - I am not enough of an electrical engineer to suggest a suitable value for the capacitor but it should have a voltage rating high enough for the circuit being switched and if switching AC it should NOT be an electrolytic capacitor.

Finally, if the problem really is being caused by the relays on the Relay Expansion not being rated highly enough for the circuit being switched, you could use the Relay Expansion relays to switch separate external relays that have a higher rating

They all seem to work again after "giving them a knock".

I will read a little on the capacitors to see if I can find a suitable value as I know very little of the matter as well!

Thanks for the suggestion.

Odd no?

Well, I tried this, and after 5 or 6 times the relays no longer locked!

All is well now

Thanks guys.

...Apparently they let the relay weld and would "unstick" it, and do this a few times...

I'm not sure if I understood right, you took the solder Iron and made the 8legs of the relays "warm" that the solder ran back to the hole of the circuit board from the extension? Without adding new solder?

Glad you're on your way. BTW, not sure your level of solder skills, but I like two of the suggestions above and would try either of them if you get more problems:

1. Replace the relay with a pin-compatible heavier-duty one (or)
2. Have the onboard relays drive the coil of heavier-duty relays

@Samuel-Mathieson make sure to post your project when it's done, I would love to see the final result.

Should I use a diode on the contacts?

Thanks for any help.

Try throwing a diode across the coil of the relay eliminating contact bounce as the culprit.