This DIY add-on switches a standard fog machine from always-on to motion-activated–increase your savings and spook factor at the same time.

Courtesy of tinker Greg, this modification involves a new relay and motion sensor mounted onto the existing switch of a store-bought fog machine. When the motion-sensor detects motion the fog machine releases a burst of fog for 5 seconds and then disarms itself for 10 seconds–long enough for the startled victim to move on and for the machine to recharge for the next passerby.

Check out the video above to see it in action and then hit up the link below to see the project’s build guide.

Motion Sensing Fog Machine Trigger [via Hack A Day]

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