This simple water level indicator will activate an active buzzer (e.g. BeStar BPT-23CX ) in order to make a noise when a certain level of water is being reached. Because the water sensor and the ...

This simple water level sensor circuit monitors the presence of water in a certain location or container. The circuit sends an acoustic alarm when it senses a drop of water leak.

Thus, you have a useful liquid level indicator with seven distinct output levels. It’s a neat build that might prove useful if you need to check levels in a big opaque tank at a glance.

Author Ejaz ur Rehman describes a an extremely simple water-level maintainer that keeps the water level between two predefined levels using an LM311.