Keep an armed guard on your door or valuables

Whether we are brave enough to admit it or not, we all suffer varying degrees of paranoia when it comes to the doors in our life. Was that someone sneaking in the front door? Did we leave the back door open? Where’s the padlock on the shed door? Should we have a mortise or a night latch?

The list goes on and on... There isn’t a day goes by when we don’t suffer some stress event associated with a door! Perhaps the circuit described here might help put some of those fears at rest. The Door Defender is a simple circuit intended to monitor the opening and closing of a single door, but it could easily be expanded into a comprehensive system.

It can be used with any type of internal or external opening, and consumes very low current in standby. For instance, the long battery life would make it ideal for protecting a garden shed. On the other hand, its small size could allow it to be a portable unit for protection when traveling.