Water Level Indicator

[Harish Dhanda]

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.

 

[Hero999]

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.

 

[hotwaterwizard2]

Here is my LowTech Approach

View attachment 41374

 

[hotwaterwizard2]

Here are a couple more.

View attachment 41375

View attachment 41376

 

[hotwaterwizard2]

http://www.free-circuits.com/circuits/alarms-control-timers/33/hot-water-level-indicator

http://zonaelektronika.blogspot.com/2010/04/water-level-indicator-with-alarm.html

http://www.engineeringslash.com/digital-ic/water-level-indicator/water-level-indicator.html

http://www.siliconchip.com.au/cms/A_30607/article.html

 

[Hero999]

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.

 

[hotwaterwizard2]

That is a great point Hero. Maybe my cork idea isn't so low tech after all. LOL ???

 

[Hero999]

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.

View attachment 41377

 

[hotwaterwizard2]

The capacitors are the trick here

74HC14 Datasheet

http://www.nxp.com/documents/data_sheet/74HC_HCT14.pdf

http://www.fairchildsemi.com/ds/MM/MM74HC14.pdf

74LS14.pdf

 

[Hero999]

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.

 

[hotwaterwizard2]

Too bad this "Single Poster" is not participating in the thread he started.

Maybe we are done here.

 

[Hero999]

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.