Introduction: Automatic Water-Tank Motor Controller

Picture of Automatic Water-Tank Motor Controller

You can see the working of this controller explained in the lovely diagram...

Its a simple controller, which would help to turn the water pump on, when your water tank is empty, and will turn it off when the tank gets full, and will keep it turned off until the tank is empty...

Step 1: Working

Picture of Working

The lower sensors acts as the 'J' input and the upper sensor acts as the 'K' input in the J-K flipflop...

the working of both the sensors is opposite, i.e. the upper sensor gives output 1 when the water is detected, and the lower sensor gives output 0 when the water is detected...

With this kinda sensing, we can predict the JK flipflop's output as-

when there is water on both sensors, input = 0 1, output = 0 = motor off

when water is coming down after filling up, input = 0 0, output = 0 = motor off

when water comes below the lower sensor, input = 1 0, output = 1 = motor on

when water starts rising from the lower sensor, input = 0 0, output = 1 = motor on

when there is water on both sensors, input = 0 1, output = 0 = motor off

Step 2: The Circuit

Picture of The Circuit

The circuit works on 12v dc power supply, which you can give from a 12v DC adapter...

The circuit is built around 3 main ICs-

LM358 - dual comparator - sensing IC

NE555 - timer ic - clock pulse generator

7473 - JK flipflop - the controller/brain

You can see the components and the connections as per given in the circuit...

The components you will need to build this circuit are -

-12v dc jack female

-1x(100uf or 200uf or 500uf or 1000uf) + 1x10uf capacitor

-7805 volt regulator + heat sink

-2x 500k potentiometer

-2x 47k ohm resistor + 2x 470 ohm resistor +1x 330 ohm + 1x 270 ohm + 1x 100ohm + 2x 10k ohm resistor

-LM358 IC + base

-LM555 IC+base

-7473 IC + base

-1x diode

-12v relay = heavy duty according to motor

-2x red led + 1x green led + 1x yellow led

-1x BC547 transistor

-12cmx12cm prefboard

-12v DC adopter

correction - the pin 2 and 6 are connected in the 555 IC in the circuit.
also do connect the Vcc and Ground of all the ICs, you will easily get the pin configuration of the ICs on google...


hari yamadri (author)2017-10-14

Bro did u have any innovative ideas

Samartist (author)hari yamadri2017-10-15

Yes, bipods, hexapods, etc

rana wasala (author)2016-11-04

its grate job very usefull for biginers

SangeethaR4 (author)2016-08-13

I am planning to try this circuit and wanted to know what kind of sensor need to be used with this circuit?


djfreestyle80 (author)2016-07-28

I want to try this..but may I know what LED do when running sir..? do they flip-flop when relay start pump "On" or else..coz i'm beginner here..thanx for information:-)

DJAdnanMalik (author)2016-07-10

nice circuit.

i need little help. actually we have utilitiy water supply problem in my area. there is no timing of water supply. so i want a circuit to start my pump after every 30 minutes if water comes the motor continue to run if water not come motor stop after 1 or 2 minute. any body plz help me


johnip4 (author)2016-02-29

It's good to see someone designing logic circuits rather than just using a micro controller. I've been using float sensors like this
They won't get dirty and will also work with fluids other than water.

anoop mu (author)2015-01-10

hi i made this ckt and its not working...7473 ic's 13 th pin is connectd to something or is it open?

Samartist (author)anoop mu2015-12-17

you need to give +ve and -ve voltage of every IC

and pin 2 and 6 of IC 555 are connected...

Samartist (author)anoop mu2015-01-10

yeah the pin is open, it is not connected to anything..

this circuit is fine, recheck your circuit
if you are still unable to debug it, then upload the pics of your circuit... i will see them...

alaam2005 (author)2015-07-12

thanks for sharing. I think the circuit diagram shows using the first half flip flop while you used the second half, isn't it?

Samartist (author)alaam20052015-11-18

yes I used just one flip flop

Harry777 (author)2015-06-06

Hello sir ...u have any video of this project ? Means designing video.

Samartist (author)Harry7772015-11-18

sorry I didn't make any video of it...

Nandup1 (author)2015-10-02

Could you tell me its cost.. ??

Samartist (author)Nandup12015-11-18

I paid about 300rs = 4.5USD for all the components.

Matt21x (author)2015-08-15

500k potentiometer or some other value?

Samartist (author)Matt21x2015-08-16

10k to 1Meg any potentiometer will work fine...

and it is also not necessary to have same pots both sides too...

Sourabh2999 (author)2015-05-09

What is voltage rating of capacitor used?

Samartist (author)Sourabh29992015-05-09

you can use any voltage actually, 16v, 25v or any other.... it doesnt matter much...

Sourabh2999 (author)2015-05-09

What is voltage rating of capacitor used?

kuttird (author)2015-02-21

Hi samartist

How does this circuit protect the pump from dry running.
Is there any other circuit which can identify dry running of the pump and which can immediately stop the pump. I would like to add dry running protection also add this circuit... Please help me..

Samartist (author)kuttird2015-02-21

there can be many things done in this circuit to see if the motor is running dry or not. One of the solution is that when a motor gets turned on, start a timer and if the motor stays on for more than expected time then we can switch off the motor and change the state of the system.

kuttird (author)Samartist2015-02-22


Samartist for your replay....

kuttird (author)2015-02-21

How to detect motor "dry run" by using this circuit ? Please add the dry run detection section also in this circuit ....

zohaib_97 (author)2015-01-25

Hi samartist ! I am new to the world of electronics and wish to make a similar circuit. Could you please help in suggesting a simple, cheapest, durable and an automated solution (with maximum safety) for prototyping the circuit below? Thank You !

I have two AC motors, one for storing water in underground tank and the other for filling up overhead tank.

I start storing water in the underground tank once it comes during designated timings on alternate days only and it takes 8-10 hrs for tank to fill completely.

Sometimes it even happens that pump for underground tank is left running (not knowingly) and the water supply from utility during the designated timings is over while filling up the tank. In this scenario, the motor uselessly runs, until someone physically see the the flow of water and then switches it off.

After I see that there is substantial amount of water present in the sump, then only i switch on the other motor to fill up overhead tank or it would burn down the motor. The tank fills up in 90mins, if it's completely empty. In this scenario too, one has to be there in time to switch off the motor once it has filled up completely to prevent overflow.

For this circuit, I would like to know the level of water using 5 LED indicators (EMPTY, 1/4, 1/2, 3/4, FULL) for both of my tanks.

More importantly, a manual switch in the circuit would be its plus point. So that if the circuit is malfunctioning, I would be able to connect the motors directly to mains.

Both are 2 HP motors and operate in 220V AC.

Samartist (author)zohaib_972015-01-26

OK i will think about your scenario... tell me can you work with microcontrollers?

zohaib_97 (author)Samartist2015-01-27

Thank you for your support. Unfortunately, I don't know to work with microcontroller :/

Samartist (author)zohaib_972015-01-28

i advice you to learn some circuit concepts...and things about microcontroller... then you can easily solve your problem...

i work on one of the cheapest microcontroller set = MSP430 Launchpad

you should learn stuff about this, and a simple comparator based water level indicator circuit too...

zohaib_97 (author)Samartist2015-01-31

Thank you so much samartist for your reply...

sks.rock.224677 (author)2015-01-30

Dear author I don't get a few things as the ckt pic is not clear.what is the need of potentiometer here??and why have u wrttn PE instead of grnd??PE is bit confusing...Thankyou man for sharing such a great project with us bt if more description of the working of opamp and other ics will be given then I think I can do this for my home.actually the main problem is the quality of the photo is not having difficulty to understand watching a cracked pic.if u can get a better quality pic then I will be very much helpful for me and others who r thinking to do this.once again thankyou so much for sharing this :)

potentiometers are there to set the sensitivity of the water sensor part...

and PE is nothing... it is same as ground....

kag432 (author)2014-06-27

What is the point of the comparators? Couldn't you just feed the sensor inputs into an unclocked flip-flop and cut your complexity in half while getting rid of 2 ICs?

Samartist (author)kag4322014-06-27

the work of the LM358 is that it gives output either 1 = 5v or 0 = 0v, if we feed the sensor directly input into the flipflop, then it wont be 0/1 but it will be in between these two...

the work of the clock is that it helps to save the input, the flip flop saves the input only on the rising edge or falling edge of the clock pulse, so we need to give it the rising edge constantly to feed in the inputs into the flipflop...

kag432 (author)Samartist2014-06-27

Okay, I was assuming the sensor was just a switch with a pull-up resistor, if not then yeah I can see you would need the comparators. For the flip-flop, what I meant was that you can get a JK flip-flop that doesn't require a clock since you don't actually care about the timing.

Samartist (author)kag4322014-06-27

if you will not give it the clock pulse, then the JK flip flop will not work... it will give undesired output with nothing as the clock input...

kag432 (author)Samartist2014-06-27

You would use a S-R or J-K latch instead of a clocked flip-flop. your circuit up to the transistor could be simplified to this schematic.

Samartist (author)kag4322014-06-27

i didnt have a NAND or NOR gate IC, so i didnt try it, you should try it in breadboard, and then see if it works, then only we should make any decision about it, But your scheme seems pretty convincing to me, but i can't say anything before seeing the physical implementation...

kag432 (author)Samartist2014-06-27

Yes, these things always look better on paper ;)

Samartist (author)kag4322014-06-27

if you will not give it the clock pulse, then the JK flip flop will not work... it will give undesired output with nothing as the clock input...

Samartist (author)Samartist2014-06-27

there are a lot of circuits in the internet to do this stuff, but this is the best circuit, it is very secure and works everywhere...

all the other circuit are made of just 1 or 2 ICs, but they dont work as desired, whereas this is very neat and robust...

Ian74 (author)2014-06-27

how about a complete parts list?

Samartist (author)Ian742014-06-27

i have added the list in the instructable, you can see it now...

Jan_Henrik (author)2014-06-27

Very cool circuit!

About This Instructable




More by Samartist:2-Bit Arithmetic and Logic UnitHandheld Gameboy - Using Arduino (with Snake Game)Clap Switch
Add instructable to: