When automating special effects, the most important part is making sure that they are well timed.  For live events such as a haunted house, the best way to get the timing right is to use sensors to detect where your guests are and when they reach various locations. So for this Halloween, I am doing a series of projects that demonstrate different sensor that can be used to automate a haunted house.

In this project, I am going to show you how to make a simple proximity sensor.