water level sensing

Thread Starter


Joined Dec 8, 2006

i 'd like to develop a project that would monitor a water level in the overhead tank at home and beep if it reaches the mark set by me.

i only want a simple ckt as i don't want to switch off pump automatically when the level reaches the set mark in tank.If i get the beep i will switch off the button.

pl do reply with the relevant details

ashish sharma


Joined Jul 17, 2007
The float switch will work well for quite a while; and it is quite simple.

Better wire it up so that it is "normally closed"; that is, normally conducting electricity.

That way, if there is a failure in making the connection, you'll be alerted.

Another approach you might consider is a metal disk suspended above the fluid by a wire which is part of the R/C of an oscillator circuit, made with a CMOS 4093 Schmitt NAND gate, a resistor, one additional capacitor, and a piezo speaker. Select the RC values so that normally, the circuit is free-running at around 28kHz. When the water gets near the disk, it will change the frequency of the oscillator lower, into the audible range. The higher the water gets, the lower the frequency, until the disk is immersed.

As a side benefit, when it's running with no water nearby to change the capacitance value, insects will be driven away by the high frequency noise ;)
use float switch which give input to non inverting terminal of opam set gain of opam to 2-3 times connect a buzzer to out put . all u required 5 v supply and 741 opam two 1k res, one res

Thread Starter


Joined Dec 8, 2006
thanks for the reply but no body has given the ckt details.pl give me the ckt
and relevant details as i m new to this.where do i get float switch?

pl give details



Joined Feb 5, 2009
This post is quite old, though I am still writing it here if you still need it you can see this. I myself used the circuit digram and built one for me. This is the LINK http://www.electronicsforu.com/efylinux/circuit/cir105.htm of the circuit.

I built this circuit after seeing it in that site. It worked fine though I had some problem with one part of the project which I have posted here. You should see the post here http://forum.allaboutcircuits.com/showthread.php?t=18943
before working on the project.