Also known as BUD switch. looks like your wiring is too big, though good job.

first its not true if you will change the block (with piston or really fast by hand) you will still get the same thing so its not placing breaking detector its BUD : Block Update Detector or what you build BUD switch that switches the output every update actually its checking for id update so its doesn't really matter if you change between 0(air) to 35(wool) or 3(dirt) to 2(grass) and it was done before and really compactor than that