I’m using a photon with a relay shield. I am powering the relay shield with a Mean Well DIN rail mounted 12VDC 0.88 Amp external power supply. I use all four relays in my application, only one relay is triggered at any given time.
I installed a new relay shield last week and only 3 out of 4 relays worked properly. Relay 3 failed about 75% of the time. The relay would be engaged, the red LED would come on, but the NO circuit wouldn’t close. If I tapped the relay (the black box) with a small screwdriver the NO circuit would close.
So I swapped out the relay shield for new one. I got the same kind of failures, but on a different relay. I swapped out for another new relay shield and got the same results. Strange, huh?
I also tried to power the relay shield with a 12VDC 30Amp power supply with the same results.
The very first one of these that I built I used a 5VDC power supply and saw this kind of behavior but it totally went away when I properly sized the DC power supply.
I have built dozens of these systems with no relay problems, then three failures in a row. Has anyone experienced something like this? Suggestions?
Thanks for your help!