This is one of the simplest water level indicator that can give three indications – Full, Half and Low water levels in the overhead tank through LED indications. The circuit is too simple and uses a single IC and a few components.
The main part of the water level circuit is the 7 channel Darlington array IC ULN 2004. Its three inputs are connected to three probes to sense the water level and the corresponding outputs are connected to three LEDs through current limiting resistors R1 through R3. A common probe (probe A) is connected to the positive rail. When this probe gets electrical continuity through water with the probes B, C and D corresponding LEDs light.
Position of probe
Probe A Bottom of tank
Probe B Upper position of tank
Probe C Middle position of tank
Probe D Lower position of tank
Simple Water level Indicator Circuit diagram
Settings
Assemble the circuit on a common PCB and enclose in a small box. This unit can be kept in a place for easy monitoring. Use brass or chromium plated pins as probes. Connect the probes with the unit using three core shield wire. Probes should be plugged into the tank through the side- Probe A and D in the lower position, Probe B in the upper position and Probe C in the middle position. If the tank is empty, only the probes A and D get current through water so that Red LED only lights. When the water level increases to half of the tank, Probe C gets continuity and Yellow LED also lights. When the tank becomes full, Probe B gets continuity and Green LED lights. In short, if Green, Yellow and Red LEDs light, tank is full. If Yellow and Red LEDs light, tank is half and if Red LED only lights, tank is empty.
Last members who liked this article
LumaMahaya
Sir,
i appriciate your work. but i want a physical modal of the same for the boiler drum is it possible with the halp of the same.
give me reply.
Sir , nice circuit & usefull
a very worthful circuit. sir could you please tell me how to interface this circuit with microcontroller 8051. as we are making a dam water level warning system and controlling using gsm.
Dear sir,
can i use a alarm in this circuit???
>When tank full, alarm active and make some noise.
Please tell me where i connect the Alarm.
And
also provide the alarm circuit.
Your student,
HN..
mmmm ALARM ???
ok…let me anserwed and help to a P.Marian…
choice an output ( depend how you accomodate your exits …and apply a buzzer
or insert a sound alarm noise
some one visit this web
RACSO
can i use a alarm in this circuit???
When tank full, alarm active and make some noise.
Please tell me where i connect the Alarm.
And
also provide the alarm circuit.i need it sir reply me its toooo urgent….
I believe you can, since a buzzer is an indicator. I think it works like an LED
sir,
I have required the IC ULN 2004 for water level control device.Can u provide
Thanking Avinash
Can we use AC current to make it work?
If yes, How much volt can we need to use for this circuit.
Do we have to make any changes to resistor?
No, it will not work on AC. To power via AC, get a wall wart power adapter –check recent article on wall warts.
Can i use a component that convert AC and give me an output of 9V DC for this circuit. Or it has to be 9V Battery.
Use a Wall Wart power adapter –it provides isolation and low voltage DC for your project.
Hi,
Circuit works fine and i have connected Buzzer too. However, when i immerse the probe in the water the LED glow is dimmed and Buzzer is sounding very low. Can you tell me what needs to be done to avoid this since i am planning to implement this for my overhead tank.
Sir,
I want to use this circuit for a well to know the water level. What will be the life of battery. Can i switch ON only when i want to know the water level.
Hi,
First of all I must thank to the publisher for this valuable circuit. I kindly like to add something. First look at the structure of the ULN2004 (http://avrlab.com/upload_files/ULN2004_structure.JPG)
The circuit has used only 3 pins but can use 7 pins which simply we can have 7 sensors with 7 LED bulbs. So I think it will be working fine. I want your advises and thanks so much in advance.