PTC removed. My OSPi v1.43+ didn’t have that specific chip. I followed the photos in Power pi and OsPi Separately. The 1.43+ didn’t have the 150 chip highlighted in the photos, but seemed to have two or three 050 chips stacked. I can confirm it seems to have had the desired effect and both Pi and all zones still work.
As for why I went with the rPi 3, I wanted wifi and figured onboard would be cheaper, easier, and better supported than a USB adapter. I may ultimately multi-task the pi into some other purposes as well.
I’m doing drip irrigation for vegetable gardens and put a valve in each of 10 beds. The valve per bed is almost certainly overkill in retrospect, but I didn’t want to dig up the yard twice and it seemed easier to have each bed connect to a single distribution pipe. I hadn’t appreciated the durations required for drip irrigating; if I want each bed watered during the morning hours its going to require having a few go at the same time.
I purchased a 60VA (2.5A @ 24VAC) supply from eBay but it was lost in the mail. The seller of the 60VA transformer from eBay also seems to have a store with the item listed. The documentation on that transformer lists the unloaded output as <= 30v. Despite their less than appealing name and poor quality picture, they’ve been pleasant enough to work work with and have sent a replacement for the one lost in the mail. After a week and a half of waiting for that, I got impatient and Amazon same-day’ed this Elk TRG2440 40VA to get my system up in the mean time. The voltage while unloaded on that ELK TRG2440 was 27v and seems to work well.