Harish Dhanda Posted March 5, 2011 Report Share Posted March 5, 2011 I want to build at home a simple and inexpensive IC based circuit for my overhead water tank to indicate level of the water by glowing 4 LED's for 25%, 50% ,75% and100%. Please Help. Quote Link to comment Share on other sites More sharing options...
Hero999 Posted March 5, 2011 Report Share Posted March 5, 2011 Use a pot and ball cock to give a varible voltage depending on the depth.Use some comparators such as the LM339 to light the LEDs depending on the input voltage. Quote Link to comment Share on other sites More sharing options...
hotwaterwizard Posted March 6, 2011 Report Share Posted March 6, 2011 Here is my LowTech Approach Quote Link to comment Share on other sites More sharing options...
hotwaterwizard Posted March 6, 2011 Report Share Posted March 6, 2011 Here are a couple more. Quote Link to comment Share on other sites More sharing options...
hotwaterwizard Posted March 6, 2011 Report Share Posted March 6, 2011 http://www.free-circuits.com/circuits/alarms-control-timers/33/hot-water-level-indicatorhttp://zonaelektronika.blogspot.com/2010/04/water-level-indicator-with-alarm.htmlhttp://www.engineeringslash.com/digital-ic/water-level-indicator/water-level-indicator.htmlhttp://www.siliconchip.com.au/cms/A_30607/article.html Quote Link to comment Share on other sites More sharing options...
Hero999 Posted March 6, 2011 Report Share Posted March 6, 2011 All good ideas John but be warned about the ones which pass DC through the water which can cause corrosion problems due to electrolytic action. Quote Link to comment Share on other sites More sharing options...
hotwaterwizard Posted March 6, 2011 Report Share Posted March 6, 2011 That is a great point Hero. Maybe my cork idea isn't so low tech after all. LOL ??? Quote Link to comment Share on other sites More sharing options...
Hero999 Posted March 6, 2011 Report Share Posted March 6, 2011 The cork idea is a good one.Doing it electronically is more complicated. Here's an idea which should work in an automotive situation where the water is already connected to the vehicle chassis. Quote Link to comment Share on other sites More sharing options...
hotwaterwizard Posted March 6, 2011 Report Share Posted March 6, 2011 The capacitors are the trick here 74HC14 Datasheethttp://www.nxp.com/documents/data_sheet/74HC_HCT14.pdfhttp://www.fairchildsemi.com/ds/MM/MM74HC14.pdf74LS14.pdf Quote Link to comment Share on other sites More sharing options...
Hero999 Posted March 6, 2011 Report Share Posted March 6, 2011 Yes, the capacitors provide AC coupling so no DC flows through the water.I notice you've attached a datasheet for the TTL/LS 7414. This circuit will only work with CMOS gates because they have a high input impedance. It won't work with older TTL gates because their input impedance is too low.If higher voltage operation is required you could use the CD40106 or 74C14 which will work up to 15V. Quote Link to comment Share on other sites More sharing options...
hotwaterwizard Posted March 6, 2011 Report Share Posted March 6, 2011 Too bad this "Single Poster" is not participating in the thread he started. Maybe we are done here. Quote Link to comment Share on other sites More sharing options...
Hero999 Posted March 6, 2011 Report Share Posted March 6, 2011 Yes, it's annoying when that happens which is why I generally write no more than a couple of lines for the first response to a thread like this. In this case I posted the schematic for your benefit as much as anyone else's. Quote Link to comment Share on other sites More sharing options...
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