Hi, I'm pretty new to modding (just started yesterday). I've learned how to make blocks, items, tools, food, recipes etc. and I was thinking I want to learn some slightly more advanced things such as redstone signals. I know how to make a block output a signal, but I have no clue how to check for surrounding blocks, how to check for updates, or how to modify the signal after the block has been placed. How can I make a block output a weak redstone signal only when the block below is air?