I have an automatic pump station that consists of a 12v DC 3 amp power supply, 2 DC buck converters, one set to 5 v DC and the other 12 V DC, an arduino Mega with a 2.8 inch tft touch screen shield, 12 parasalitic pumps 12 V each, and 6 dual channel relays that run on 5v DC.
In short a user uses the tft touch screen to enter commands and the pumps run accordingly to what the user selected. This is done by turning certain relays on and off that have the 12v power from the buck converter. From the 12 V DC buck converter I am running the mega, the tft touchscreen, and all the pumps. From the 5v buck converter I am running all the relays. There will never be more than 3 pumps running at the same time.
My issue is getting power to the 6 relays. I think I destroyed my first 6 relays when I placed a common ground between the 12v and 5v power supplies. Can someone confirm this and give me a work around? Also, could I just use the 5v pin of the arduino mega to run all the relays and remove the 5v supply all together? I am worried about the amp usage from this.
Please see the attached schematic. Any help is appreciated.
What makes You Think the relays are blown and not the Mega?
Because the touch screen still work and I can test the mega and it's fine. However I had to replace the relays and they failed basic testing.
What is Your wiring describing? Is this the original, before You encountered trouble or after You removed some ground wire? I see a common ground to the left of the +5 and +12 converters.
The 6 relays, down in th drawing… Are they relay modyles have logic drivers or did You connect the relay coils to the Mega?
Have You tested the Mega I/O that was connected to the relays?
This is the original wiring before I added a ground wire between the 5v and 12v buck converters. Please note I added the ground wire after the converters and this is what killed my relays.
The relays at the bottom do have logic. They are the ones you can find all over the internet people use with jumper wires.
I have tested the mega pins and they are all working properly.
Are the GNDs coming into the 5 and 12 volt at the left side passing through without circuitry to the right side, or, are the input side and output side of the 2 converters galvanicaly separated? That could be a serious issue.
If possible, disconnect the 5 and 12 volt converters. Then use an ohm meter and measure the connection between IN-minus and OUT-minus.