Water level sensor using transistors

[burrow]

Hai,
i am using water level sensor made up using transistors, Before i was using leds so small fluctuations was not a big problem but now iam feeding a microcontroller, So i noticed that signal fluctuates. Something like from level 4, it shows level 6 for a second.
I think the water level probe is picking up raw voltages ( or whatever it is called )

In the transistor side iam using a 220 ohm resistor in the base, and also a 10k pull down.

Whats the solution?, will changing resistors to a higher value solve the problem?

 

[Damienmac]

Hi

Putting the signal through a low pass filter would probably solve this. Are the fluctuations sustained or do they only occur when the water level changes?

 

[FvM]

Can be better answered with a circuit schematic.

 

[burrow]

Hi

Putting the signal through a low pass filter would probably solve this. Are the fluctuations sustained or do they only occur when the water level changes?

It fluctuates all the time.

 

[Audioguru]

It is winter time now. Frozen water (ice) does not fluctuate.

 

[burrow]

It is winter time now. Frozen water (ice) does not fluctuate.

. I am from south india. here temperature hardly goes below 15 degree Celsius.

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Hi

Putting the signal through a low pass filter would probably solve this. Are the fluctuations sustained or do they only occur when the water level changes?

that May work.But fluctuations maybe very slow or may be too fast

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Can be better answered with a circuit schematic.

I dont have circuit diagram handy. But its simple, 6 level sensing probe, each of them goes to base of transistor BC547 through a 220 ohm resistor, it has a pull down of 10k.

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Iam going to modify the circuit a bit, Iam going to add a priority encoder before microcontroller, I am planning to use 74LS148. So it will be priority encoder thats providing input for the microcontroller.

From water level probe signals will go to transistor and then to priority encoder.

So i have a query, Should i add pull up resistors to the inputs of the encoder( input will come from transistor's collector) ?