Water Level Indicator

Water Level Indicator

Description

This is the circuit diagram of a simple corrosion free water level

indicator for home and industries. In fact the the level of any

conductive non corrosive liquids can be measured using this circuit.

The circuit is based on 5 transistor switches. Each transistor is

switched on to drive the corresponding LED , when its base is

supplied with current through the water through the electrode

probes.

One electrode probe is (F) with 6V AC is placed at the bottom of tank.

Next probes are placed step by step above the bottom probe. When

water is rising the base of each transistor gets electrical connection to

6V AC through water and the corresponding probe. Which in turn

makes the transistors conduct to glow LED and indicate the level of

water. The ends of probes are connected to corresponding points in

the circuit as shown in circuit diagram.Insulated Aluminum wires with

end insulation removed will do for the probe. Arrange the probes in

order on a PVC pipe according to the depth and immerse it in the

tank.AC voltage is use to prevent electrolysis at the probes. So this

setup will last really long. I guarantee at least a 2 years of

maintenance free operation. That’s what I got and is still going.

Components

T1 – T5 BC 548 or 2N2222 Transistors

R1-R5 2.2K 1/4 W Resistors

R6-R10 22K 1/4 W Resistors

D1 – D5 LED’s ( color your choice)

Notes:

Use a transformer with 6V 500 mA output for power supply. Do not

use a rectifier! we need pure AC. Use good quality insulated

Aluminum wire for probes. If Aluminum wires are not available try

Steel or Tin.Copper is the worst. Try the circuit first on a bread board

and if not working properly, make adjustments with the resistance

values. This is often needed because conductivity of water changes

slightly from place to place. The type number of the transistors used

here are not critical and any small signal NPN transistor will do the

job. Few other suitable type numbers are BC546, BC107, PN2222,

BC337, BF494, ZTX300, BEL187 etc. The circuit can be enclosed in a

plastic box with holes for revealing the LEDs .

Water Level Indicator Circuit Diagram and Sensor Arrangement.

Water Level Indicator

If you need a fully automatic water level controller circuit then try this

circuit Water level controller. The circuit is fully based primarily on

transistors. The sensing section is somewhat similar to this circuit but

there is additional circuitry for switching the pump ON when the

water level falls below a set level and the pump will be switched OFF

when the tank is full. Few transistors , one 555IC and an

electromagnetic relay is used for realizing the control section. The

circuit is very simple cost effective , reliable and many guys have

successfully assembled it.I am also working on a float type water level

indicator/controller using the float type fuel gauge mechanism used in

motor cycles.

Ic 7404:

Pin configuration of ic7404 is as shown in below.Ic7404 is NOT gate circuit it has 6 NOT gates

in it.

NOT gate1:

input: pin1 output: pin2

NOT gate2:


NOT gate3:


NOT gate4:


NOT gate5:


NOT gate6:


Pin 7: ground pin14: +Vcc

Ic 7408:

Pin configuration of ic7408 is as show belowIc7408 is a 2input nand gatesIt has 4 nand gates in

it.

AND gate1:

input pins:1,2 outputpins:3

AND gate2:


AND gate3:


AND gate4:

input pins:12,13 outputpins:11Pin 7: ground pin 14: +VccThe ciruit is constructed using these

two ic’s (ic7404,ic7408) and the sevent segment displaysthe circuit is as shown below

How it works:

This water-level indicator uses a 7-segment display, instead of LEDs, to indicate the water

level(low, half and full) in the tank. Moreover, a buzzer is used to alert of water overflowing

from thetank. The circuit shows the water level by displaying L, H and F for low, half andfull,

respectively. The circuit uses five sensors to sense the different water levels in the tank.Sensor A

is connected to the negative terminal (GND) of the power supply. The other four sensors (B

through E) are connected to the inputs of NOT gate IC 7404. When there is a highvoltage at the

input pin of the NOT gate, it outputs a low voltage. Similarly, for a low voltage atthe input pin of

the NOT gate, it outputs a high voltage. When the tank is empty, the input pins of IC 7404 are

pulled high via a 1-mega-ohm resistor. So it outputs a low voltage. As water starts filling the

tank, a low voltage is available at the input pins of the gate and it outputs ahigh voltage.

When the water in the tank rises to touch the low level, there is a low voltage atinput pin 5 of

gate N3 and high output at pin 6. Pin 6 of the gate is connected to pin 10 of gate N9, so pin 10

also goes high. Now as both pins 9 and 10 of gate N9 are high, its output pin 8 alsogoes high. As

a result, positive supply is applied to DIS3 and it shows ‘L’ indicating low level of water in the

tank. Similarly, when water in the tank touches the half level, pins 4 and 5 of AND

gate N8 become high. As a result, its output also goes high and DIS2 shows ‘H’ indicating

half level of water in the tank. At this time, pin 9 of gate N9 also goes low via gate N4 and

DIS3stops glowing. When the water tank becomes full, the voltage at pin 1 of gate N1 and pin 3

of gate N2 goes low. Output pin 3 of gate N7 goes high and DIS1 shows ‘F’ indicating that

thewater tank is full. When water starts overflowing the tank, pin 13 of gate N6 goes low to

makeoutput pin 12. The buzzer sounds to indicate that water is overflowing the tank and you

need toswitch off the motor pump.We can Assemble this circuit easily on a general-purpose

PCB and we can enclose it in a suitable box. we can Use a non-corrosive material such as steel

strip for the five sensors and hang themin the water tank as shown in the circuit diagram.We can

use 5v power supply or 5v adapter as +Vcc

Advantage:

i)No need to waste time to observe the water level time to time,

i i ) W a s t a g e o f w a t e r c a n b e p r e v e n t e d

iii)By using automatic switches instead of alarms we can turn off them automatically, sowe can

make its switching off completely independent of human

Disadvantage:

We can’t completely depend on these circuits because if any of probes which are atmaximum

level or the probe which is at bottom level gets disconnected or broken it will notfunction

correctly. So we have to provide security to it.

Water Level Indicator

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