Thanks for the advice.
I'm looking at an 8A power supply - which should be more than enough, I was finding that anything higher than that I was needing to get from China.
This is really for some christmas tree lights, so I don't imagine I'll be adding lots more other than the original 100...
My plans are stuck at the moment, as I need one of these :
https://thepihut.com/products/adafru...o-5v-74ahct125 - but they're out of stock everywhere
---------- Post added at 12:23 ---------- Previous post was at 10:49 ----------
Been having a dig around, so I've found this :
https://thepihut.com/products/adafru...-level-shifter but I think that only shifts from 5v to 3.3v - so don't think that would do.
but... I was rummaging through my component box, and I found one of these :
https://thepihut.com/products/adafru...verter-txb0108
That should let me shift from 3.3v to 5v right?