Embedded Lab

Hard water contains more minerals (calcium and magnesium) than ordinary water. Although it is non-toxic, it is less desirable as it can clog water pipes and complicate soap and detergent dissolving in water. It also builds up scales in water heaters over time, thus shortening their operational lifetime. In residential units, hard water is usually softened by installing a water softener unit connected directly to the water supply line. The water softner exchanges salt for the dissolved minerals, which results in softer water. David Cook’s water softener appliance stores the salt supply in a brine tank, which requires refilling in every few weeks. Until now, the only way Dave could know that the tank is empty was when his wife complained that the dishwasher, soap or shampoo was not working. So, for uninterrupted water softening, Dave has made a salt level monitor for the brine tank. The device uses a 10-element LED array to indicate the salt level in the tank. He used an infrared sensor to measure the salt level in the tank. This data is processed by an AVR ATtiny861 microcontroller and displayed it on the LED bargraph. A light-dependent resistor is also implemented in the project as a smart switch to save battery power. The LED bar graph display is auto-turned off until the room lights are turned on or somebody approaches the monitor panel, which changes the room brightness level.

Water softener salt level monitor