Filament Thickness Switch

If you have a 3D-Printer, which can already recognize if Filament has used up, then you can add this gadget.
Sometimes, if you use 2nd grade filament, it happens, that the diameter is not always the same. Some bubbles come along. These would not pass the extruder and the fiamtent stucks. Then the print fails, as the printer does not recognize that it is printing with air only.
But if you put this gadget in the line of your "end of filament switch", the printer will pause for too thick filament too.
The wiring of both switches has to be serial.
Cut one wire from the "end of filament switch" and connect in this "filament too thick switch"