I am in the UK, so any links to products will be ones I can get hold of. I've tried to not be too specific- everything will also be available elsewhere in the EU/US. A lot of parts can be ordered most cheaply from China if you can wait for the shipping.
You will need:
, I used a pi zero W but any pi will do, old pi a/B and pi zeroes use the least energy- if you're thinking of taking this project off grid.
A micro sd card
to fit in said pi, I recommended 16GB or more. No need for anything massive though.
A one wire interface
of some kind, I use the sheepwalk electronics ones: https://www.sheepwalkelectronics.co.uk/index.php?cPath=22
The RPI2 v2 for the pi zero, or the RPI3 v2 for larger pi- this provides more transport buses and is suitable for more sensors, or sensors going off in vastly different directions.
DS18B20 temp sensors
- either the TO92 ones, or the waterproof version if you need them to be waterproof, some ebay links as examples: https://tinyurl.com/y3xqh4ak
Cat 5 or cat 6 cable
, and a kit to fit your own rj45 ends to these is handy as well- you’ll need the rj45s themselves, i recommend the ones with a loading bar, or pass-through connectors- for ease of getting the wires fitted, like these: https://tinyurl.com/y3g6yd9x
You’ll also want an rj45 crimping tool.
RJ45 3 way connectors-
buy more than you need as they’re all really jippy. The black plastic moulded ones are better than the cream plastic ones, like these: https://tinyurl.com/y2bryeh8
. Or you could go for the sheepwalk electronics 4 way connectors, these are ace- RPI3a port splitter, https://www.sheepwalkelectronics.co.uk/product_info.php?cPath=22&products_id=34
You will need a few things to develop on the pi. If you have a separate PC/laptop and wifi then all you’ll need is a microsd card reader. You will also need a monitor and keyboard with the relevant adapters to connect to the pi.