Heat detector

A heat detector would be crafted with 6 stone, or cobblestone, 3  red stone dust, observer, and a bucket of lava. It will detect if it is in the nether, desert, near any fire, lava, furnace, and campfire (if lit or cooking) and anything else that produces heat.

This will detect at full in the nether, near lava, and if in the desert. Fire, Furnaces, torches and campfires will produce a lower signal. The further the heat source is, the lower the signal. Ex: if you put it near a pool of lava, it will make a lower signal if it was right next to it. This could be useful for redstoners, as you can start signals with lava, or fire, and everything else that makes heat. You can also make greif detectors, is anybody tries to burn your house down. Nice for furnace timers, and for traps, if someone goes into a unlit cave, and more!