Water Level Indicator Using Transistor

Water Level Indicator Using Transistor

Here we are going to present  a low-cost wireless water level indicator without an MCU with explanation in simple language.

This circuit has transmitter and receiver units. The transmitter unit is placed near the water tank, whereas the receiver unit is placed inside the house for monitoring four different levels: low, middle, full and overflow.

Components

1. BC548 transistors-Q1,Q2,Q3,Q4
2. Resistors R1,R2,R3,R4-2.2kohms
3. R5, R6 ,R7 – 100 ohm
4. Led – Red(LED3) , Green(LED1) , Yellow(LED2)
5. Metal Contacts – M1,M2,M3,M4. 

Circuit

Working

1. The circuit is designed to indicate three levels of water stored in the tank: low but not empty, half and full but not overflowing.
2. When there is no water in the tank, all the LEDs are off as an indication that the tank is completely empty.
3. When water level increases and reaches M2, the contacts M1 and M2 get shorted as water acts as a conducting medium between M1 and M2.
4. This will turn on the transistor Q1 and the Green LED starts to glow. As the water level continues to rise and reaches half the tank, M3 will come into contact with water and receives a small voltage from M1.
5. As a result, Q2 is turned on and Yellow LED will glow. When the water in the tank rises to full tank, M4 is also shorted with M1 and both Q3 and Q4 will turn on.
6. The Red LED glows and also an alarm is made by the buzzer as an indication that the tank is full and the water pump or motor can be turned off. 

 Note:This circuit does not show a buzzer.Connect a Buzzer,resistor and transistor  in series and connect this in  parallel to the last LED

Water Level Indicator Using 555 Timer

Components

• NE 555 Timer
• Resistors 

       R1,R4-1K

       R2-22k

       R3-570 Ohm

• Capacitor- 1UF
• Buzzer
• Connecting wires

 Circuit:

Working:

The circuit uses a 555 timer in astable mode with R1=22k ohms, R2= 570 ohms and C1=1 uF. The frequency of the given astable circuit is around 62 Hz.

The two probes which are shown in the circuit should be kept at the high level for the water. The distance between the probes should be less than a few centimetres to ensure that the conduction between the probes will take place when water is touched to these probes.

When the water level rises to the height of the probes, then the 555 circuit will get enabled and the output of the 555 timer produces a square wave output with a frequency of about 62 Hz. This output is given to the buzzer.

The logic Implemented in this circuit is, 555 timer is enabled when its reset pin is connected to logic high. But initially it is connected to ground. When the water level is maximum this pin is enabled and this drives the 555 timer into astable mode.