[51] sensing continuously varying water level & displaying it on LCD.

[amit251291]

Hello Everyone,

I am doing one project. I have made one water level sensor which gives me output in current that varies from 0mA to 17mA approximately when watel level varies from 0 level to FULL level. Now after this i want to sense this level using 8051 and display this continuously varying water level on LCD.
So my idea was to convert this current output into voltage by I to V converter and then feed it to ADC to get digital values and then through 8051 it can be displayed on LCD. I checked voltages too (after I to V converter)& those were ranging between 2V to 5V (for above mentioned current) and with difference of approximately 0.02V.
So is this the correct way ?? Should i use current amp/voltage amp ??
or any other better way is there ??

 

[jayanth.devarayanadurga]

You can take voltage across a resistor of value 294 ohms by passing the 17 mA current. You will get 0V for 0 mA and 5V for 17 mA. No need for amplifier. What sensor are you using. Is it a continuous potentiometric sensor? Provide the link for the sensor.

 

[amit251291]

You can take voltage across a resistor of value 294 ohms by passing the 17 mA current. You will get 0V for 0 mA and 5V for 17 mA. No need for amplifier. What sensor are you using. Is it a continuous potentiometric sensor? Provide the link for the sensor.

oh yeah right. No its a normal sensor. I have taken 2 copper plates which i have fixed at the same distance. I have given supply to these plates. To these 2 copper plates i have attached wires(through which i am measuring current). i have fixed this unit to the bucket and started pouring water, as the level of water increases, current flowing through this water also increases and its range is the same which i have mentioned above.

 

[jayanth.devarayanadurga]

Don't pass continuous current instead pass current like burst for a small amount of time every few seconds like pass current for 5 sec every 60 sec.

 

[amit251291]

Don't pass continuous current instead pass current like burst for a small amount of time every few seconds like pass current for 5 sec every 60 sec.

okay sorry but i did not get purpose of doing so

 

[jayanth.devarayanadurga]

Re: sensing continuously varying water level & displaying it on LCD.

To save current.

https://www.practicalarduino.com/projects/water-tank-depth-sensor

 

[paulfjujo]

hello,

What is the Voltage level applied to the electrodes..?

Because in case of short circuit you have to protect
the MCU ADC input..because voltage must be over 5V to be able to get 5V on ADC input!
So you can add a R Limit and a Zener 5.1V as described..
Rlimit value depend of the used voltage ..

And to avoid any problem due to electrolyse effect, you can use a simple relay
with 2 inverser contact to inverse the electrodeq after xx minutes or after N measurements
controled by an output of MCU (under software controle).

 

[amit251291]

Re: sensing continuously varying water level & displaying it on LCD.

Thank you jayanth.devarayanadurga

- - - Updated - - -

hello,

What is the Voltage level applied to the electrodes..?

Because in case of short circuit you have to protect
the MCU ADC input..because voltage must be over 5V to be able to get 5V on ADC input!
So you can add a R Limit and a Zener 5.1V as described..
Rlimit value depend of the used voltage ..

And to avoid any problem due to electrolyse effect, you can use a simple relay
with 2 inverser contact to inverse the electrodeq after xx minutes or after N measurements
controled by an output of MCU (under software controle).

View attachment 101147

Thank you Voltage i have applied is 5 volts!

 

[paulfjujo]

so, with 5V ,you can not insert a resistor an get 5V across it !
You must use 10V minimum to get 5V across electrode and 5V across resistor.
(it means same cureent 17mA for maximum scale)

but to check that behavior with water electrolyte resistance when using 10V instead of 5V
Response could be not linear . Volt= F(depth)
can be arranged by software lookup table.