Contactless Liquid Level Controller System using pic microcontroller

Contactless Liquid Level Controller System: Contactless liquid level controller system is very significant system for maintaining the desired level of any liquid such as water or oil in a close tank. Water or any liquid saving tanks are commonly used on commercial or industrial level and with these tanks motor or pumps are normally used for maintaining the desired liquid level. But with these tanks, motor or pump control system is very important because if these are not timely on /off then so much quantity of liquid or water could be wastage on daily basis. SO many control systems are available in market such as a manual or automatically on/off system and with these systems sensors or limit switches are installed inside the water or liquid tank. The inside limit switches or sensor creates installing and maintenance problems. Here we have designed a system that is called a contactless liquid level controller system with the help of transformer, pic microcontroller 18F452, ultrasonic sensors, relay, LCD display and voltage regulator. In this system, ultrasonic sensors are installed outside the liquid or water tank, in other words they do not have any link with water or liquid, therefore they do not create the installing or maintenance problem and this system timely on/off the motor or pumps.

Block Diagram of the Contactless Liquid Level Controller System

Here is the block diagram of contactless liquid level controller system with all essential components,

Figure 1 Block Diagram of the Contactless Liquid Level Controller System

Components List with Detail of Contactless Liquid Level Controller System

Transformer: Because this contactless liquid level controller system is directly powered up with 220V ac supply, therefore transformer is used for step down the 220V ac into 12V ac. It works on the principle of mutual induction.

Bridge Rectifier: Because the whole contactless liquid level controller system is operated on dc supply therefore the bridge rectifier is used for converting the ac voltages into dc voltages. It consists of four diodes.

Blocking Diode: In this system, the blocking diode is used for blocking the reverse polarity current, in other works it provides the protection of transformer.

Voltage Regulator: The contactless liquid level controller system is mostly consisting of electronics components, which are normally operated on 5V dc, therefore the voltage regulator is used for regulating the 12V dc into 5V dc and for this purpose the LM 7805 voltage regulator IC have been used here.

LCD Display: In this contactless liquid level controller system, the LCD display is used for displaying the liquid level and motor or pump current condition means it is in on/off condition. It is powered up with 5V dc and is interfaced with microcontroller.

Ultrasonic Module: In this contactless liquid level controller system, the ultrasonic module is used for on/off the motor or pump when liquid or water level is falls or up the desired level. This ultrasonic module consists of ultrasonic transmitter and ultrasonic receiver. The ultrasonic transmitter sends the high frequency sound pulse and this pulse is reflected after the collision of desired object. This pulse is received by ultrasonic receiver and then on/off the connected things. It is powered up with 5V dc and is interfaced with microcontroller.

Pic Microcontroller: In this contactless liquid level controller system, the PIC 18F452 microcontroller have been used for the intelligent control of this system. It 40 pins integrated circuit IC, powered up with 5V dc and interfaced with ultrasonic module, LCD display and load transistor. Microcontroller is programmed in c language with help of mikro/c software.

BC 547: In this contactless liquid level controller system, the BC547 is a NPN bipolar junction transistor which consists of three terminals emitter, base and collector. This transistor is commonly used for amplifying the current Small current is applied at its base terminal which controls the large current at its emitter and collector terminals.

IRFZ 44: In this contactless liquid level controller system, the IRFZ44 is power MOSFET, which consists of three terminals, gate, drain and source. Control signal is applied at its gate terminal and load is connected at its drain to source terminal. This MOSFET is used for controlling the high current and high voltages.

Relay: In this contactless liquid level controller system, the relay is used for on/off the output load.

Load: In this system lamp is used for as an output load.

Working Principle of Contactless Liquid Level Controller System

This contactless liquid level controller system works on the principle of signals which are sent or received by the ultrasonic sensors. These ultrasonic sensors are installed outside the liquid or water tank and its range is almost 250cm.These sensors switch on the motor or pump when the water or liquid level is below from 30cm similarly these sensors switch off the motor or pump when water or liquid level is above 30 cm. In other words, 30cm is its desired level point. Here for the demonstration purposes we would be check this system by connecting the lamp and as an output load. We would be analyzing the motor or pump on/off position by checking the lamp on/off position. When we would be placed anything within the range of 0 to 30 cm then ultrasonic sensor gives the digital high signal to microcontroller then microcontroller gives the digital high signal to BC457 transistor then BC 457 transistor switch on the output lamp through relay and MOSFET IRFZ 44. Similarly, when we would be placed anything above the range 30cm then transistor BC457 switch off the output lamp.

Applications and Advantage of Contactless Liquid Level Controller System

1. This contactless liquid level controller system could be used in oil or chemical industries with their tanks for maintaining the oil or chemical level automatically within the desired range.
2. This system could be installed in homes with water tanks for maintaining the water level automatically.
3. This system has low maintenance and installation cost.
4. This system is more efficient and less costly as compared to the others system.
5. This system very easy to install.