Here is a circuit called Water Level Controller Using 555 Â which continuously monitors the level in the overhead and ground-level tanks, and switches on the pump whenever the water level in the overhead tanks falls below a predetermined level and switches off the pump whenever it reaches the maximum preset level so that there is no spillage.
Further, if the level of water in the lower tank falls below a preset low level, this circuit overrides the commands being sensed from the overhead tank and switches off the pump. This overriding facility is unique for this circuit and ensures that the pump never runs dry. All these functions can be handled by the single NE555 integrated circuit.
Working of the Water Level Controller Using 555
The levels in the upper and lower tanks are sensed by electrodes mounted on the tank. There are three electrodes in the upper tank named A, B, and C as shown in the circuit diagram. Similarly, there are two electrodes in the lower tank named D and E as shown in the circuit diagram.
Let us now consider the situation when the water level in the lower tank is high and both the rods are submerged in water. Since water is conductive, transistor T1 will get saturated and LED1 will glow. The IC will also be able to sense the signals from the two comparators.
Initially, the overhead tank is empty and as such, there is no connection between the three electrodes A, B, and C. Electrode B is connected to the ground through resistor R5. Since electrode B is open, the potential at pin 2 is drawn towards the ground. This triggers the lower comparator is signal the flip-flop to go low and the output at pin 3 goes high. This operates the relay through transistor T2 and the pump starts operating.
Other Water level indicators and controller circuits posted in bestengineeringprojects.comÂ
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- Water Level Indicator Circuit
When the level of water reaches the upper rod A, the current being to flows from the reference rod C to A via resistor R7 to the ground. Since the resistance between rod C and A is lower in relation to R7, the potential at pin 6 reaches nearly the supply voltage. This triggers the upper comparator to signal the flip-flop to go to a high state and consequently the output at pin 3 goes low. This de-energized the relay and the pump switches off. This condition will continue until the level of water in the overhead tank falls below the lower reference rod B when again a pulse at pin 2 will energize the relay.
However, if during the pumping operation or thereafter, the level of water in the lower tank reaches a level lower than the rod D, the transistor T1 will go out of saturation, LED1 will extinguish and the flip-flop will get a negative potential through pin 4, immediately resetting the flip-flop to a high state. The input at pin 3 will be forced low thereby de-energized the relay and switching off the pump.
The pump can be switched manually by momentarily depressing switch SW1. It can be switched off by depressing SW2. Capacitors C1 and C2 help prevent false triggering due to line transients.
PARTS LIST OF WATER LEVEL CONTROLLER USING NE555
| Resistor (all ¼-watt, ± 5% Carbon) |
| R1, R10 = 3.9 KΩ
R2 = 100 KΩ R3, R4, R6, R8, R9 = 1 KΩ R5, R7 = 68 KΩ |
| Capacitors |
| C1, C2 = 10 µF/16V (Electrolytic Capacitor)
C3 = 0.01 µF (Ceramic Disc) C4 = 1000 µF/25V (Electrolytic Capacitor) |
| Semiconductors |
| IC1 = NE555 (Timer IC)
T1 = BC148 (Silicon NPN Transistor) T2 = SL100 (General purpose low power transistor) D1 = 1N4002 (Rectifier Diode) BR1 = General purpose bridge rectifier LED1, LED2 = Red LED, 5mm LED3 = Green LED, 5mm |
| Miscellaneous |
| RL1 = 9V, single pole relay
X1 = 230V AC to 9V, 250mA transformer SW1, SW2 = Push-to-on switches |
Dear sir,
first of all i’am very thankful to you for the very good and the useful (water level controller 555) article which u posted here.
can u please clarify me that can i power the circuit with 12v, 500ma transformer and replacing the 9v relay with 12v…..?
awaiting 4 ur valuable reply…….:) Thanks in advance.
very useful and good working circuit.
Pls give your number
Hi Diven Patel, If you vane any queries then please post here or message us on facebook page thankyou
We can use 12V. I am using the circuit of 12v and 12v relay. It is working fine. No change done in the circuit.
Yes you can use 12V, no need to modify the circuit.
Hi Mr. Patel,
You have given a wonderful circuit for automatic water level control. Can I use 12V DC and a 12V relay for the same circuit.
Please reply.
I had not check the response on 12V, but can work with little or no adjustment.
Please give it a try and let us know.
Hello can I get assembled pcb photo for reference?
The circuit seems to be good.
Please inform, if the sensor wires are very long, say about 30 Mtrs., whether it will work then?
If not, please mention the changes required.
You can use 30Mtrs wire for the sensor without modifying the circuit.