This document describes a simple water level indicator circuit using a NE555 timer IC. The circuit uses two probes - one at the bottom water level and one at the top water level. When the bottom probe is uncovered, the 555 output goes high, triggering a relay that powers a motor. When the top probe is covered, a transistor resets the 555, turning the motor off. The circuit provides an automatic way to measure and control water levels to reduce waste and electricity consumption.

1. SIMPLE WATER INDICATOR
CIRCUIT TO MEASURE THE
LEVEL OF ANY LIQUID
Prepared by
Baranitharan
Computer Science and Engineering
Kings College of Engineering

2. Components required
• Power Supply(6v)
• NE 555 timer IC
• Resistors (100Ωx2, 10kΩ)
• Relay (6V, 30A)
• BC 548 transistor x2
• 1N4007 Diode

3. Circuit

4. How Does It Work
• We know the property of 555 timer IC, i.e. its
output goes HIGH when voltage at the second pin(trigger pin) is
less than 1/3 Vcc.
 Also we can reset back the IC by applying a LOW voltage at
the 4th pin (Reset pin).
• In this project 3 wires are dipped in water tank.
Let us define two water levels- Bottom (Low)
level and Top (Up) level. One of the wire or probe
is from Vcc.

5.  The probe from bottom level is connected to the trigger (2nd) pin
of 555 IC. So the voltage at 2nd pin is Vcc when it is covered by
water.
 WHEN WATER LEVEL GOES DOWN, THE 2ND PIN
GETS DISCONNECTED(UNTOUCHED) FROM WATER
I.E. VOLTAGE AT THE TRIGGER PIN BECOMES LESS
THAN VCC. THEN THE OUTPUT OF 555 BECOMES
HIGH

6. WHILE THE WATER LEVEL RISES, THE TOP LEVEL PROBE IS
COVERED BY WATER AND THE TRANSISTOR BECOMES ON. ITS
COLLECTOR VOLTAGE GOES TO VCE=0.2.
THE LOW VOLTAGE AT THE FOURTH PIN RESETS THE IC. SO
THE OUTPUT OF 555 BECOMES 0 VOLT. HENCE THE MOTOR
WILL TURN OF AUTOMATICALLY.

7. For simple demonstration of this project we can use a
DC motor directly at the output of 555 instead of relay.
For practical implementation we must use a relay.
Rating of relay is chosen according to the load(motor).
32A relay is best suited for domestic applications.

8. NE 555 timer IC

10. Conclusion
 It is used to find the level of any liquid
 It is used to reduce the wastage of any liquid
 It is used to avoid the electricity consumption.
 It is used to make our home as smart