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water tank controller using 89c51

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garg29

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hi friends
i'm trying to build a water tank controller using 89c51 ....to prevent salt formation on probes i m generrating a 2000hz frequency from uC and transmitting it to the water tank .for detection of water level m using a small circuit comprising of 1 m ohm resistor , capacitor(0.1 uF) and bc548 ...but the circuit is highly sensitive...even a small touch of a finger or something on the probe is detected by the circuit....please suggest me how i can improve the working and efficiency of the circuit .... attached below is the circuit diagram i made....

thanks,

With Best regards,
Amit
 

Maverickmax

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Hello Amit

Why don't you use magetic reed swtich instead?

You just put a plastic tube inside the water tank and insert a cork with magentic inside the tube so the cork will float. Put the reed swtich outside of the tanker.

The floating magnet can be used to monitor a predetermined low-level mark by activating an adjacent reed switch on the side of the butt. Remember you can put many reed switch as you like which allow you to measure the level of water.

Maverick Max
 

garg29

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Thanks for the great idea. I think this would be a lot useful to me in near future. But just for knowledge purpose i want to know how to make (my kind of circuit) stable and less sensitive.
 

controller

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put a resistor base to emiter of bc548.
 

guttinasrinivas

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A crude method is add a variable resistor across the 0.1µF capacitor (across base and ground) and try at various levels of pot setting. At some point, you'll surely catch the balance.

Srinu
 

superman2009

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I am not sure wether garg29 has alreday done this project. As per my point of view, i have worked in similar design where the frequency from the water is rectified to DC, and then attenuated to required level which is then fed to the microcontroller.
 

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