Letter Box Sensor

A letter box sensor is actually a specialist form of door contact sensor that is either small enough to be fitted to the letter box or is a small sensor mounted remotely, on the end of some wires.

To enable a sensor that is invisible, we have mounted a reed switch inside the letter box frame and have mounted a tiny, powerful magnet on the inside letter box flap.

There are several reasons for installing a sensor in our letterbox:

• Our contextual smart home can see when mail has been delivered and send notifications if required.
• Like all sensors our letter box inherits the ability to provide occupancy and presence information and this is used by a controller to control lighting (the porch light in this instance).
• We can get voice announcements if the context requires it (e.g. we are at home).
• With some very simple configuration, we can ensure we get a when the letter box has been stuck open by post for more than a few minutes. This avoids cold draughts coming through it in the winter months.
• The sensor is also configured to trigger a security camera by the front door, so we have footage of people putting things through our letterbox.