Friends help me in my automated tank filler project ?

[yusuf]

Friends I have make a automated tank filler project led indications.But I am facing some unpredictable results, while putting the probe in water my first led lights up.But while removing the probe my led's light dimily.
I want to solve this problem.if i put my probe in the water then led should light bright and while removing the probe my leds should turn off..
this is my circuit diagram please help me guys thanks in advanced

 

[SABorn]

What are S1-S4...Relays?

The circuit draws too much current through the water and the probes will corrode real fast and the circuit will stop working.

Using probes in water is really a poor system in my opinion, and the only method to reduce corrosion is to use AC and not DC current through the water.

 

[Reloadron]

I believe S1 through S4 are a quad bilateral switch like the CD4066. I agree with Pete in that the circuit likely will not perform well. At average ambient temperature you would need a minimum of 2.75 volts to turn any of the switches on. You would need pretty conductive water for this to work. Additionally as Pete implied, the probes will be short lived due to corrosion.

Ron

 

[alec_t]

There is also the problem that connecting the BC148 base resistor to pin 12 will shunt the 180k resistor and prevent the 'full' indication working.

 

[Boncuk]

According to the pinout of S1 to S4 it is a bilateral switch CD4066. Additionally S1 to S4 are labeled CD4066 in the circuit schematics.

Besides getting excessive corrosion on the probes you will certainly experience the electrochemical process of electrolysis - with the probes diminishing with usage.

A better approach is using an NE555 wired as astable multivibrator and supplied with ±6V at a duty cycle close to 50% you are able to avoid electrolytic effects.

Use the positive return signal from the probes to rectify and smoothen it and feed the signals into four comparator circuits for distinctive indication of the water level.

Using strips or bars of stainless steel your probes will stand forever. They just need to be cleaned from possible lime deposit for equal conductivity from time to time.

Depending on water purity 180KΩ might not suffice for rain water which opposes a resistance of near 1MΩ for clear indication. (I used a water resistance of 10MΩ between probes (10mm) for proper function.)

Using the resistive method for water level detecting the above described method is very reliable.

I'm using a differential pressure sensor to indicate tank level with the accuracy of 10l out of a 1,200l tank. The inaccuracy is not caused by the sensing method but by the tank shape which is a half sphere at the bottom.

Boncuk