i need help on desinging a Linear water level indicator

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4la

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i need help on desinging a Linear water level indicator, can anyone pls help?
 

i have worked on designs that take level measurement at four discrete points but i need to work on one that measures the liquid level all through the tank linearly not at points. pls help
 

4la,

The best approach seems to be with an microcontroler ( with A/D built-in module ) reading a pressure sensor.
Precision may be low if level range don´t be high enough to fit the entyre sensor scale.
In other way, a AmpOp would be needed.

As posted by ckshivaram, target application details helps us to sugest a more precise solution.

+++
 

if you need a simple circuit you need only a bistable multivibrator using 555.
Please provide more requirements. So we can know your concept more accurately
 

hi Thunder

But what kind ok sensor must be connected at both inputs 1 and 2 ?

+++
 

thunderboympm said:
no i think about a bistable multi vibrator
Click to expand...

The OP has asked for a "Linear water level indicator" , you solution can only work as an alarm when the level goes above/below a certain level, it is a on/off solution.
To get an linear level indicator you need some king of sensor that gives a result which depends on the water level.

Alex
 

4la said:
i need help on desinging a Linear water level indicator, can anyone pls help?
Click to expand...

Assuming the water characteristics won't change a lot, you may use two long isolated electrodes to form a varying capacitor taking advantage of the difference of the dielectric constants of air and water (1 vs. 80). The change of the water level will reflect a change in the oscillator frequency for example (or the charging time). But I am not sure how good the accuracy will be, and if it is possible for you or not to use two long isolated metal electrode having a good surface with water (to increase the capacitance which helps I guess).
On the other hand, perhaps measuring the water conductivity can also be made to give a practical indication about the water level. But in this case the electrodes should resist corrosion.
I always liked to do such a linear sensor using rather a simple circuit but I didn't have the time... yet.
 
KerimF said:
...perhaps measuring the water conductivity can also be made to give a practical indication about the water level...
Click to expand...

I already tryed that approach in the wall water detector of an ice machine.
The problem is that parameter varyes, mainly against temperature ( even at low range ).

+++
 
i really need to have the level of water in the tank linearly displayed on a three seven segment display***
 

andre_teprom said:
hi Thunder

But what kind ok sensor must be connected at both inputs 1 and 2 ?

+++
Click to expand...

Only a transistor is enough

---------- Post added at 01:47 ---------- Previous post was at 01:22 ----------
I just think about the water level controller. If need a lenear sensor , a simple float or potentiometer and lm3917 is enough. It is very simple. I done it.
 

thunderboympm said:
...If need a lenear sensor , a simple float or potentiometer and lm3917 is enough...
Click to expand...

Electronically, seems to be very simple.
However, mechanically, assembly of the apparatus to support this set, seems to be imprecise, due # of turns need to fit all water path.
( 1 turn of trimpot should be multiplyed to some meters by some mechanism )

+++
 

OP,
You have to give more details :
tank height, working temperatures, fixed or mobile(on a ship),
desired response time, etc.

Till then, here are some design start points:
A.
1- Analog Output Pressure Sensor<- Freescale,Honeywell etc.
2- Op Amp, eventually
3-Cheap DMM*

1- Pressure Sensor<- Freescale,Honeywell etc.
2- Attiny13A
3- MC14499 for common cathode LED displays
4- 7-Segment 3 digit LED Display of your choice

Freescale gives free samples for some pressure sensors, find a temp. compensated one with needed range of pressure ; with a 1 bar (100kPa)
sensor you can measure a tank with 10 meters of water height.


* DMM = Digital Multi Meter :roll:
 

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