water level indicator

So here goes the problem definition...

a tank should have 2 sensor mounted at 75% and 25% empty/filled level. The tank will contain water whose level at 75% and 25% of tank capacity should be identified by the system and the motor should be turned on or off accordingly i.e if water level falls below 25% filled, start the motor to fill the tank and if water level exceeds 75% mark, stop the motor.

I have been suggested to use 89s52 controller which I am okay with. I can design the flow chart of the project and write the code also, but...

I dont know which sensor to use to detect water level
Because, whatever I may use, it must be cheap and should keep water away/isolated from current.

Can anyone tell me names of some cheap sensors which can detect water level???

---------- Post added at 18:21 ---------- Previous post was at 18:07 ----------

I have already searched through google, but cudnt get sensor which keep water isolated from current during working.
I have also read the similar topics on this site...but they didnt have apt solution

Various sensor types can achieve isolated measurement:
- capacitive sensors
- AC conductive sensors with a transformer
- optical sensors (based on total reflection)
- floaters operating a magnet/reed switch
- sensors based on thermal conductivity
and much more

Check this pdf file it might help you.

**broken link removed**

Good luck

Check out these links.It may help you.
Water Level Indicator.
**broken link removed**.
Regards,
Jerin.

---------- Post added at 04:51 ---------- Previous post was at 04:45 ----------

Check out these too. It may give you the idea of the sensor you have to use.
Water Level Sensor, water level switch, water level indicator, water level measurement, water level control, fluid level sensor, water level meter.
**broken link removed**.
Level Control ~ Level Sensor ~ Liquid Level ~ Level Indicator ~ Float Switch ~ Liquidlevel.com.
Sensors: / Detectors:* Water Sensors.
Regards,
Jerin.

incomplete_jerin said:

Check out these links.It may help you. Water Level Indicator. **broken link removed**.
Regards, Jerin. Check out these too. It may give you the idea of the sensor you have to use.
Water Level Sensor, water level switch, water level indicator, water level measurement, water level control, fluid level sensor, water level meter.**broken link removed**. Level Control ~ Level Sensor ~ Liquid Level ~ Level Indicator ~ Float Switch ~ Liquidlevel.com. Sensors: / Detectors:* Water Sensors.
Regards,Jerin.

Click to expand...

If you have no clue, just dont post. The first two link are just different links for the same project. I can just see more advertsiing links than the expected answers.

i am seeing his post in most of the thread in micro controller section.

I had posted so much links so that he could find what he wants from the group & sorry if i have posted more repeated links.
Regards,
Jerin. :sad::|

thanks for the links...
but most of them, I already searched n cudnt find as per my requirement.

I am thinking of using "floating switch"
...any idea abt it?

Search the site of analog devices they have some usefull devices to solve you problem. maybe an ad7153 or one with multiple channels