Obviously only 1 and 4. Neither book or post uses tech. It can talk about tech, describe it, but never use it in any manner. Mum's doorbell might be gray area

Obviously only 1 and 4. Neither book or post uses tech. It can talk about tech, describe it, but never use it in any manner. Mum's doorbell might be gray area as you can easily say that it's still your doorbel, you just chose to install it wherever you chose to install it.