So I bought a 24V / 12V power supply (the silver box) to supply the 24V for the sprinkler valves and 12V for the relay board. The relay board generates 5V for the Raspberry Pi Zero W board. I learned last week that sprinkler valves use 24V AC, not DC. You can get away with DC but it will take more power and is just not right. This is ok, since I was never crazy about the big power supply.
So I bought this wall wart power supply to get the 24VAC and this neat little converter to get 12VDC from the 24VAC. Hooked it all up and it works. Oh, originally bought a Rasperry Pi Zero without the header soldered in. Figured I could do it myself. Didn’t have the right equipment and / or the skills and really botched the soldering job. Bought another one with the header soldered in. Good thing those Pi boards are so cheap.