Generally water stored in overhead tank is wasted due to over flow when the tank is full. Water level alarm using micro-controllers like 8051 and AVR are shown in previous articles.This article shows simple circuits of water level indicator with alarm.
Three circuits were shown here are simple and built using transistors, 555 timer and ULN2003 IC. First let us build a water level alarm using simple transistors.
Outline
- Water Level Indicator Using Simple Transistors
- Circuit Diagram
- Components Required
- Working
- Water Level Alarm Using 555 Timer
- Circuit Diagram
- Components Required
- Working
- Water Level Indicator and Alarm Using ULN2003
- Circuit Diagram
- Components Required
- Working
Water Level Indicator Using Simple Transistors
Circuit Diagram
Components Required
- BC548 transistors-Q1,Q2,Q3,Q4
- Resistors R1,R2,R3,R4-2.2kohms
- R5, R6 ,R7 – 100 ohm
- Led – Red(LED3) , Green(LED1) , Yellow(LED2)
- Metal Contacts – M1,M2,M3,M4.
Working
- The circuit is set up to show three levels of water in the tank: low but not empty, half full but not overflowing, and full but not overflowing.
- All of the LEDs are turned off when there is no water in the tank, indicating that it is fully empty.
- Water acts as a conducting medium between M1 and M2, therefore when the water level rises and reaches M2, the contacts M1 and M2 become shorted.
- The transistor Q1 will be turned on, and the Green LED will begin to shine. M3 will come into contact with water and get a modest voltage from M1 as the water level rises until it reaches half the tank.
- 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.
- 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.
Water Level Alarm Using 555 Timer
Circuit Diagram
Components Required
- NE555 Timer
- Resistors
- R1,R4-1K
- R2-22k
- R3-570 Ohm
- Capacitor- 1UF
- Buzzer
- Connecting wires
Working
The circuit operates in astable mode using a 555 timer with the following values: R1 = 22k ohms, R2 = 570 ohms, and C1 = 1 uF. This configuration results in an approximate frequency of 62 Hz.
In this circuit, two probes are used to maintain a high water level. To ensure that these probes conduct when they come into contact with water, their separation distance should be less than a few centimeters.
As the water level reaches the height of the probes, it triggers the 555 circuit. The 555 timer, initially held in reset by being connected to ground, is enabled. This action shifts the 555 timer into astable mode, producing a square wave signal with a frequency of around 62 Hz. The buzzer is then driven by this signal.
Water Level Indicator and Alarm Using ULN2003
One can implement this circuit using simple ULN2003 IC.IC ULN2003 consists of an array of seven Darlington transistor pairs.
Circuit Diagram
Components Required
- L1-L3-LEDs
- R1-R3-1k ohm
- M1-M7-Metal Contacts
- ULN2003 IC
Working
- This circuit can be used to indicate three levels of water in tanks.
- When metal contact is reached ,each Led starts glowing.
- When the tank is full buzzer starts ringing along with this all LEDs are ON.
