Advanced version
For more sensitive control of the door, there is an advanced version called Balanced Magnetic Switch, in which the electrical contact of the switch is held in no-alarm condition by two magnets - one is fixed to the door frame and the other magnet is fixed to the corresponding position on to the door. As long as the magnetic field remains balanced with the door firmly closed, the contacts within the switch would be in no-alarm condition. Even with a slight movement of the door from the door frame the magnetic field gets unbalanced causing the Control Unit to sound an alarm. The balanced magnetic switch is more tamper-resistant than a simple Magnetic switch but requires higher skill and time for installation.
