K8056 - relays sticking


I’ve built a k8056 kit and am switching 240volt AC inputs to turn on and off 8 PSUs of 8 external USB hard drive enclosures. The power usage of the enclosures is less than 3amps.

The problem I have though is that a couple of the relays are sticking in the on position - even when I turn off the 240volt source. To free them I’ve had to remove the relays covers and tap the switch - then they spring back to normal.

Is there anything that I can do to stop this happening - or have I got faulty relays ?

sounds like they are faulty - Either put a bit of conduction paste on the contacts which might stop them stiching, but be careful not to short the contacts. Where exactly is it sticking, the contact, or the hinge?

The contact.

OK, so try scraping off any residue or anything on the contact with a screwdriver - obviously WHEN THE POWER IS OFF, and see if that makes a difference

I’ll give it a try - I’ll also source some paste.


no problem - tell us how it goes :slight_smile:

I am also trying to switch some electrovalves with the K8056 boards.

These electrovalves work with 230VAC and use about 7W each. So, i plugged the INPUT source directly to a wall socket. When i did that, the house-circuits blow off and the metal between the INPUT pins and the diodes burned right off. I replaced them with wires now.

What am i doing wrong?? Maybe a have a shortcircuit on the board?

The relay work well with the test button and with the pc. Expect relay 1 that does not react (either it does not work, or i have made a shortcircuti somewhere).



Please note that this is a 12V powered kit, not a 240VAC powered kit !!!

The relay outputs however, are suited for 240VAC operation.

Ok Velleman. Maybe i did not understood.

there is one input socket - marked 12 VAC.
and a output socket marked 12 V (so DC).

If i want to control a device that works on 230VAC what should i do:

1. put a 12VAC on the INPUT terminal
2. place the device on one of the SK sockets (example SK 3) ?
    = so relay3 will connect the SK3 to the INPUT terminal??

Or ??

I suppose the 12V output is generated by the power regulator that transformes de 12VAC into 12V DC?

Thank you for a clarification,

ps: evidently i don’t know squat about electronics. yet, i managed to solder all the pieces and to repair the board after begin plugged to 240VAC :slight_smile:

You should power the kit with 12VAC.
The relay outputs are switches, they do not source any voltage
Basically, you interrupt one wire of your 230VAC circuit and connect it to a relay output.

For your and other peoples safety: Please have your hook-up inspected by somebody with experience before plugging it in.

Ok Ok. This is very clear now.

What it supposed has that the power that goes into INPUT will be the one the will aliment the circuits controlled by the relays.

So, you can have 8 different circuits (each with different power sources) controlled by the K8056.

In fact, you should probably put 1 or 2 example, use-cases, for the board in each you show exactly how you hook up devices (circuits) to the K8056.

Thank you ! It is all cleared now :slight_smile:

ps; this forum is very very helpfull.

UPDATE: you can power the board with a 12V DC source that you connect to the OUTPUT +12V socket. it works. hope this is normal !?


Is it correct that we can power the board with 12V DC?