I managed to build a control for motorized window blinds. I was using a standard no-name two-channel relay-card (to be precise: this one: http://yourduino.com/sunshop2/images/products/large_218_2-relay-isolated-1.jpg). I'm using one relay to let the blinds go up and one to move them down.
This works great until some time passed. Then only one direction will activate and the other doesn't react. The relay was the whole time connecting the „normal open“ switch and didn't fall back. You can hear the relay „clicking“ but the connection doesn't change.
So I thought that something happened with the relay and used another very similar card. The same thing happened. In both cases it was the relay for the down-direction in my case located on the same side of the card. Maybe that's random, maybe it has a reason.
Has someone an idea why this could happen? I'm not using the isolation-feature but simply using the VCC and GND of my microcontroller (strictly speaking a Photon, no Arduino, but shouldn't matter in this case). The driven motor runs with 230 V. Unfortunately I do not have any information about the current or actual motor used.
Thanks in advance for any help and/or advice.