I just found out via YouTube about a very cool redstone feature that I would like to share with you. The idea: There are several things that a block can do which currently does not send any redstone signals, but where you maybe want to know when it happens. such as a furnace is finished baking things or grass is growing on a dirt block. This has probably even more applications, comment if you know others. The cool feature is that it makes a piston expand temporarily. In connection with a flipflop this can permanently switch on power or switch it off. I found the instruction on a video online. A sample setup can be found in the piston ministry top floor.