I needed a simple LED indicator showing that a particular voltage level had been reached—specifically, that a capacitor had charged to a particular potential. I was convinced that there must be a way ...

There are many applications where the accuracy of a digital or analogue (bar graph) is not required but something better than a simple low/high indicator is desirable. A battery charge level indicator ...

Often, the only liquid level indicator you need is your eyes, such as when looking at your cold beverage on a summer’s day. Other times, though, it’s useful to have some kind of indicator light that ...

Most of the homes in the area where [Raikut] lives have tanks on the roof to hold water. Each is filled from a well using a pump, with gravity serving as a way to pressurize the home’s water supply.