Best supported doorbell [Doorbird, Ring, Fubar, 433]

Oy1974

The doorbel in fact generates a magnetic field when your press the button then a current run trough the coil wich generate a magneric field and that magnetic field let the bel ring. So your door sensor use the same magnetic field. 

phil_s

Cool! Someone a picture of this? If Not i will try. But would be great. 

Thx for this great idea 

edit: i used Google search and realized that this only works with an non digital gong. 

But the idea was great. :-)