Source google image: http://4.bp.blogspot.com/-dxZS2nS5bGI/U0X2501OtDI/AAAAAAAABHQ/2lyzIm08vCA/s1600/interphone1.jpg
Schema electrique interphone bpt
Source google image: http://4.bp.blogspot.com/-dxZS2nS5bGI/U0X2501OtDI/AAAAAAAABHQ/2lyzIm08vCA/s1600/interphone1.jpg