The coffee maker which [Donald Papp] utilizes every morning has a water reservoir on the back that can last for a number of days. This implies he forgets to inspect it as well as from time to time will return to discover that nothing has brewed. He chose to add a low-water sign to the machine. His method is about as easy as it gets as well as we admire that accomplishment.

If it were our job we’d most likely try to complicate it in one method or another. The utilize of a microcontroller as well as ultrasonic rangefinder (like this storage tank level sign from a February links post) would be overkill. No, [Donald] boiled down the electronics to a homemade switch, a blinking LED, as well as a battery. The switch is a versatile piece of metal connected to a plastic cap utilizing some monofilament. The cap goes in the reservoir as well as floats up until the water gets as well low, it then pulls on that metal, completing a circuit between the battery as well as the LED. That’s it, issue solved.

Now he just needs to plumb the coffee maker into a water line as well as he’ll truly be set.