Simple Water Level Indicator Circuit using IC ULN2004

This water level indicator circuit is like a team of tiny workers for your tank.

It uses a special chip ULN2004 to control several parts at once.

While the chip itself can handle strong electricity, in this case it is being used to manage indicator lights that show you the water level in your tank.

So, with the help of this circuit you can easily see if your tank needs more water or if it is overflowing.

Circuit Working:

Parts List:

This water level indicator is designed to provide simple and clear indications of water levels in an overhead tank.

The circuit is basic utilizing a single IC and a few additional components.

The key component of the circuit is the 7 channel Darlington array IC ULN2004.

Each of its seven inputs is connected to a probe for sensing water levels, with the corresponding outputs linked to three LEDs via current limiting resistors.

A common probe is connected to the positive supply.

When this probe establishes electrical continuity with the other probes through water the respective LEDs illuminate.

To assemble the circuit, use a common PCB and enclose it in a small box for convenient placement.

Use brass or chromium plated pins as probes, and connect them to the unit using three core shield wire.

Install the probes into the tank from the side positioning the low probes at the bottom half probes in the middle, and high probes at the top.

When the tank is empty no LEDs will be lit.

As the water level rises green LEDs will illuminate to indicate the increasing water level.

When the tank is full the red LEDs will turn on.

In summary, if the green and red LEDs are all lit the tank is full.

Formula:

From the above circuit diagram, we can use the formula for Power Dissipation and Heatsink from IC ULN2004:

Power Dissipation and Heatsink:

The maximum power dissipation rating of ULN2004 is provided.

Heatsinking may be necessary if you are using large currents via the outputs, thus make sure to compute power dissipation.

Pd = (V_out) * (I_out)

where:

• V_out is the voltage applied to the output volts
• _Iout is the current flowing through the output amps

Crucial Information:

For more information on parameters like as maximum current and voltage ratings, consult the ULN2004 datasheet.

Datasheets may also include power dissipation curve information to aid in the evaluation of heatsink requirements.

The internal architecture of the ULN2004 is enough for the majority of typical applications, negating the need for further computations.

The ideas discussed above, nevertheless, can be useful in some situations.

How to Build:

To build a Simple Water Level Indicator circuit using IC ULN2004 you need to follow the below mentioned connection steps:

Prepare the PCB:

• Design or obtain a PCB layout that accommodates the ULN2004 IC, resistors, LEDs and probe connections.
• Place PCB according to the layout.

Assemble the components:

• Solder the ULN2004 IC onto the PCB, ensuring correct orientation.
• Connect the current limiting resistors to the anodes of the LEDs and then connect the cathodes of the LEDs to the outputs of the ULN2004 IC.

Connect the probes:

• Connect the seven probes to the inputs of the ULN2004 IC.
• Ensure that one probe serves as the common probe and is connected to the positive rail.

Enclosure:

• Place the PCB inside the small box and secure it in place.
• Make holes in the box for the probes to pass through.
• Seal the box to prevent water from entering.

Connect the probes to the tank:

• Insert the probes into the tank through the side with the low probes at the bottom half probes in the middle and high probes at the top.
• Use the three core shield wire to connect the probes to the PCB.

Testing:

• Power up the circuit and fill the tank with water.
• Verify that the LEDs light up according to the water level.
• Ensure to follow safety precautions while working with electronics and water.

Conclusion:

To conclude, the water level indicator circuit using the ULN2004 IC offers a straightforward and reliable method for monitoring water levels in an overhead tank.

By utilizing the ICs darlington transistor array and a few additional components the circuit can accurately indicate the water level with the help of LEDs.

This project is relatively easy to build and can be a useful addition to any water management system.

References:

Water level indicator using ULN2803

Datasheet IC ULN2004