Leo,
My diagram did show a Hi-Link 1D1212 instead of the intended 1D0505. Again, sorry about that as it did cloud the issue.
A USB wall plug is the easy path and what I originally used, but I have a couple of reason why I have switched to a 12V supply.
I can have a common supply for the solenoid and the Nano with 12V
I can use a common power source for all the controllers (remember one for each device).
This is currently what I have in the workshop and it’s cleaned up the wiring significantly.
At some point I may share the design with my local woodworking community and if so, would have great difficulty controlling the quality of the power source used.
My understanding is that if I use a “7805 after the 12>12volt isolator” the current draw is limited to 84mA. If I use a 7805 before a 5>5volt isolator a can have a current draw of 200mA. As I say, I’ve tested the later and it seems to work OK. It would be good to understand if my logic is correct regarding the current draw and if there’s any fundamental issue with what I’ve tested.
Thanks
Michael