In this project, I am going to show you several ways that you can use a motion sensor to automate your Halloween setup.
Step 1: How Passive Infrared (PIR) Motion Sensors Work
I will attempt to give a brief summary here.
Passive Infrared (PIR) motion sensors work by detecting the movement of heat. They detect heat with a pair of pyroelectric elements that turn the incoming heat into a small electrical signal. The pyroelectric elements are wired in the opposite polarity to each other. So the signals normally cancel each other out. But when a heat source moves in front of the sensor, it creates a series of positive and negative pulses that are detected by the microprocessor. The PIR sensor then outputs a HIGH signal to indicate that motion was detected. This signal can then be used to trigger other circuits such as lights, alarms or cameras.