Water Softener Level Detector Keeps You Out Of Trouble With Wife

Some households have water supplies that contain higher than desired levels of minerals. This condition is called hard water. There is nothing harmful about hard water but it does leave mineral deposits on pipes and appliances and makes cleaning a little bit more difficult. The solution is to have a water softener system which is basically a tank filled with salt that the household water passes through. This tank has to be refilled about every month and [David] was catching a little flak from his wife because he kept forgetting to fill it. He then set out to do what any great husband would do and built a Water Softener Monitor that reports the quantity of salt in the basement tank up to the living quarters.

[David] started thinking that he should test the salinity of the water to determine if salt needed to be added but after thinking about it for a while decided against it because any metal in that salty water would surely corrode. A non-contact approach would be to use an IR distance sensor mounted to the top of the tank and measure the distance to the pile of salt that slowly lowers as it dissolves into the water. In this case, he used a Sharp GP2D12 that can measure accurately from 10 to 80cm.

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Tiny external system monitor makes it easy to keep tabs on your PC


Instructables user [Jan] likes to keep close tabs on his computer’s memory usage, but wanted something more interesting to look at than the standard resource manager. He preferred to have an external display available that would show his computer’s status with a quick glance, and thus this system monitor was born.

His status panel contains a trio of constantly updated LED bars that show his computer’s CPU usage, available physical memory, and virtual memory consumption. With a small footprint being a priority, [Jan] kept the indicator’s size down by using SMD components and by including an on-board UART to USB converter to go along with his ATTiny microcontroller.

He uses a Python script to gather usage information from his computer, feeding it to his display over USB. The system works pretty well as you can see in the video below, though the virtual memory indicator doesn’t seem to get a ton of action – perhaps it could be used to indicate hard drive activity instead.

If you are looking to build something similar, [Jan] has made all of his code and schematics available for anyone’s use.

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