Current Sensing Outlet Switch

The Story Behind the Project

My workplace got a new laser cutter, that has one flaw: the air filter is an entierly seperate device that has a very loud fan and needs to be manually turned on and off by crawling under a desk before and after every cut. We were trying to come up with a way to detect whether the laser cutter was active and use that to switch the air filter on, and I came up with the idea to use a current sensor, since the laser cutter will be drawing more current to move the head and power the laser when active. It works pretty well, and loud fans are only on for exactly as long as they need to be without having to worry about it nowadays.

Features

• Adjustable threshold current with the red knob, so the same box can be used for different types of equipment that draw different current levels on idle.

• Adjustable timeout for how long to stay on after the last trigger event, allowing for immediate power off, or in this case, staying on for another minute to remove excess fumes.

• Indicator LEDs show if the outlet is on, and more importantly if the current threshold is being exceeded at this instant, making adjustments easier