How to Make an Ideal Automatic Water Level Controller and Indicator Circuit

This perfect or ideal water level controller circuit idea was proposed and requested to me by Mr. Bilal Inamdar. The designed circuit is presented here in the article along with the required specs, in  details.
The circuit is exclusively designed and drawn by me.

Here goes the request:

Sorry for mistakes but writing from iPhone so bear in mind
Here is paste from notes 
The perfect automatic water level controller & amp; indicator.

Imp note– English is not my native language so errors are expected. I m using a iPhone to post this note so please bear with me. You can add or delete or modify anything from this note as per you need.

Need of the circuit – Well simply I want add a acrylic sheet bellow my tank which will contain tube lights. In short acrylic ceiling. The tank level can’t be observed because of the sheet. This is Also needed for terrace tank 1500 Ltrs to observe level indoors without going outside.

How it will help – It will help in many scenarios like to observe terrace tank level, to observe and operate overhead tank level and to observe underground tank water level and operate the motor. Also it will save precious water from wasting due to overflow (go green). And release the tension caused due to human error ( forgetting to turn the pump on &filling the water also turn off the motor)

Application area :-
Overhead tank
Size – height = 12″ width = 36″ length = 45″
the tank is used for drinking, washing & bath.
The tank is 7 foot above the flooring.
The tank is kept in the bathroom.
Material of the tank is plastic (or PVC or fiber whatever non conductive)
The tank have three connection
Inlet 1/2″, outlet 1/2″ and whirlpool (overflow) 1″.
The water fills from inlet. The water comes from outlet for use. The overflow connection prevent water overflowing on the tank and channelized it to drainage.
The hole of outlet is lower and the overflow and inlet is higher on the tank (ref height)

Scenario :-
The tank probes and level
|_A probe (overflow)
|__ok level
|_D probe (Medium)
|__low level 
|_B probe
|__verylow level
|_C common probe

As per the scenario I will now explain how the circuit should work

Circuit notes:-
1) Input of the circuit 6v AC/DC (for backup) to 12 AC/DC (for backup)
2) The circuit should mainly work on AC ( my mains is 220-240vac) with use of transformer or adaptor this will avoid probe rusting which occurs due to positive negative stuff. 
3) The dc will drives from 9v battery easily available  or from aa or aaa battery.
4) We have lots of power cut so please consider backup dc solution.
5) the probe used are aluminum wire 6mm. 
6) The resistance of water changes as per location so the circuit must be universal. 
7) There must be a sound which is musical as well as different for very high and very low. It can go bad so ext sound is preferable. A buzzer is not suitable for big room 2000 sqft. 
8) The reset switch must be a normal door bell switch which can be put in existing electric board.
9) There must be atleast 6 led 
Very high, very low, ok, low, mid, motor on/off. The mid must be considered for future expansions.
10) The circuit should indicate led of light gone when there is no AC current.
And switch to dc back. or add two led for indication On AC and On battery.

Circuit functions.
1) Probe B – if the water goes below this a indication led of very low must glow. The motor should start. The alarm should sound. The sound must be unique for very low level.
2) if the reset switch is pressed than the sound must go off everything else remains the same ( circuit armed, led glowing, motor)
3) if the water touch probe B the sound must be killed automatically. The very low indication led turn off the Low indication led turn on nothing else
4) Probe D – if the water touch probe The low indictor turn off. The ok level led turns on
5) Probe A – if the water touches this probe the than
The motor turns off
The ok level led goes off and the very high level led glows. 
The bell/ speaker turns on with different tune for very high. Also if the reset button is pressed in this case than also there must be no other effect rather than killing the sound.

Last but not least the circuit diagram should be expandable to E,F,G etc for very big tank (like mine on terrace)

One more thing I m not able to know how the mid level should be indicated.
Too tired to write more sorry.

my name is Bilal Inamdar
Name of the project (just a suggestion) Perfect Water Tank level automation or perfect tank water level controller.

Parts List for the above diagram:
R1 = 10K,
R2 = 10M,
R3 = 10M,
R4 = 1K,
T1 = BC557,
Diode = 1N4148
Relay = 12 volt, contacts as per pump current rating.
All Nand gates are from IC 4093

Circuit functioning of the above configuration

Assuming the water level to be at point A, the positive potential from point “C” in the tank reaches the input of N1 through water, making the output of N2 go high. This triggers N3, N4, transistor/relay and horn#2.
As the water comes down, below point “A” the gates N3, N4 maintain the situation due to the latching action (feedback from its output to input).
Therefore horn#2 remains switched ON.
However if the upper reset switch is pressed, the latch is reversed and maitained to negative, switching OFF the horn.
In the meantime, since point “B” is also at positive potential, keeps the output of the middle single gate low, keeping the relevant transistor/relay and horn#1  switched OFF.
The output of the lower two gates is high but has no effect on the transistor/relay and horn#1 because of the diode at the base of the transistor.
Now suppose, the level of the water falls below point “B”, the positive from point”C” is inhibited and this point now goes logic low via the 10M resistor (correction required in the diagram which is showing 1M).
The output of the middle single gate immediately becomes high and switches ON the transistor/relay and horn#1.
This situation is maintained as long as the water level is below point B.
However horn#1 can be switched OFF by pressing the lower PB, which reverts the latch made from the lower couple of gates N5, N6. The output of the lower two gates becomes low, pulling the base of the transistor to ground via the diode.
The transistor relay switches OFF and hence horn#1.
The situation is maintained until the water level again rises above point B.

Parts List for the above circuit is given in the diagram.

Circuit functioning of the above configuration

Assuming the water level to be at point A, the following things can be observed:
The relevant input pins of the gates are at high logic due to the positive from point “C” coming via the water.
This produces a logic low at the output of the upper right gate, which in turn makes the output of the upper left gate high, switching ON the LED (bright glow, showing the tank is full)
The input pins of the lower right gate is also high, which makes its output low and therefore the LED marked LOW is switched OFF.
However this would have made the lower left gate output high, switching ON the LED marked OK, but due to the diode 1N4148 it keeps its output low so that the “OK” LED remains OFF.
Now suppose the water level falls below point A, the upper two gates reverts their position switching OFF the LED marked HIGH.
No voltage flows through 1N4148 and so the lower left gate switches ON the LED marked “OK”
As the water falls below the point D, the OK LED still glows because the lower right gate still remains unaffected and continues with a low output.
However the moment water level goes below point B, the lower right gate reverts its output because now both its inputs are at logic low.
This switches ON the LED marked LOW and switches OFF the LED marked OK.

Parts List for the above circuit is given in the diagram

IC 4093 PIN-OUT Diagram

Please remember to ground the input pin of the remaining three gates which are not used.

In all three ICs would be required constituting 16 gates, only 13 will be used and 3 will remain unused, the above precaution must be followed with these unused gates.

All the relevant sensor points coming out from different circuits must be joined together and terminated to the appropriate tank sensor points.

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