Sunday, March 17, 2013

Making a Multi function Water Level Controller Circuit

The following multi-function water level controller circuit post is based on the suggestions expressed by Mr.Usman. Lets learn more about the requested modifications and the circuit details.

The Suggestion:

"Hi Swagatam,

The concept of this circuit looks good. May I suggest a couple of other desirable features?

1) To protect the motor from potential overheating (or as a safety feature) can u add an automatic shutdown timer? If the motor is running for one hour (or 1.5hrs or 2-hrs) and the water level does NOT reach the level-sensor, the motor should be automatically stopped. Of course, it can be re-started manually by pushing the start button again.

2) Can the motor be manually stopped at any time? For example, what if one wants to water the lawn (or wash the car) for a few minutes using high pressure water directly from the motor?"

Thanks very much!

Your suggestions are interesting!

I think I have discussed these issues in the following artricle:

However instead of a timer I have used a temperature sensor circuit for tripping the motor if it starts getting hot.

The motor can be manually stopped by shorting the base of T3 to ground. This can be done by adding a push button across these terminals. 

So the upper push button may be used for initiating the motor while the lower button may be used for stopping the motor manually.

Thanks Swagatam for a prompt reply. Ive found another circuit on your blog (April 20th post) that is closer to what I have in mind.

I want a slightly different control logic in the above circuit:

Motor START Logic:
Manual push button (already implemented)

Motor STOP Logic:
1) Water level reaches a pre-determined level (as implemented in April 21st post), OR
2) A pre-determined time has lapsed (e.g. 30, 60 or 90 mins, this requires a long time-delay/counter), OR
3) Manual stop (manual override), OR
4) Power faliure (load shedding), this is implemented by default!

So I guess, the STOP logic (1, 2 and 3) can be configured to the base of T1 (in your April 20 post) and it should work. Pls comment, and if you have time maybe you can make a new post!


The Design:

Lets analyze the above requirements and check how they have been implemented in the following diagram:

1) Water level reaches a pre-determined level: Point A and B may be appropriately fixed inside the tank for regulating this function. Since point B is situated at the bottom of the tank, remains connected with the water permanently, now as the level rises and comes in contact with point A, the positive potential from point A connects with point B, which instantly reset pin#12 of the IC, switching OFF the relay and the entire system.

2) A predetermined time has lapsed: This feature is already present in the below given circuit. The timing outputs can be increased to any desired extents simply by increasing the values of P1 and C1.

3) Manual stop (manual override): This feature is actuated by SW2, pressing which resets the IC pin#12 and the entire circuit. 

4) Power failure (load shedding): During a possible power failure or instantaneous power "blinks", the IC needs to be supplied with the required supply voltage so that the timing does not get interrupted. This is very simply done by adding a 9 volt battery to the circuit.

 As long as normal power is present, the cathode of D3 stays high keeping the battery switched OFF from the circuit. The moment power fails, the cathode of D3 becomes low, providing a way-in to the battery power which smoothly replaces the supply to the IC without causing any "hiccup" to the counting operation of the IC.

Parts list for the above explained multi-function water level controller circuit

R1= 1M, 1/4 watt
R3 = 1M
R2, R6 = 4K7
R4 = 120K
R5 = 22K
P1 = 1M preset horizontal
C1 = 0.47uF
C2 = 0.22uF disc ceramic
C3 = 1000uF/25V
C4 = 100uF/25V
D1, D2, D3, D4 = 1N4007,
Relay = 12V/SPDT
SW1,SW2 = Bell push type of button
IC1 = 4060
T1, T2 = BC547
TR1 = 0-12V/500mA
BATT - 9V, PP3

Water level buzzer indicator circuit

The following circuit of a water high level and low level indicator circuit was requested by Mr.Amit. Please read the comments given below to know regarding the exact specs of the requested circuit.

Circuit Description

The above shown water high and low level buzzer indicator circuit may be understood with the following points:

Point C which is connected to the ground or negative of the supply rail is kept immersed in the tank water at the bottom level such that the water present in the tank is always held a logic low.

Point B is the low level sensor point which must be positioned near the bottom of the tank, distance may be set as desired by the user.

Point A is the high level sensor, which should be held somewhere at the top of the tank as per user preference.

When the water level reaches under the point B, point B goes high due to R6, making the output of N4 high and consequently producing a low at the output of N5....the buzzer B2 starts buzzing. 

However in the meantime C2 starts charging up and once its fully charged inhibits the positive potential at the input of N5.....the buzzer is switched OFF. The time for which the buzzer remains On may be determined by the values of C2 and R5.

In an event the water reaches the top level of the tank, point A comes in contact with the low logic from the water, output of N1 becomes high and the same process is repeated as explained above. However this time B1 starts beeping, only until C1 gets fully charged.

Five gates from the IC 4049 have been utilized here, the remaining one unused gate input should be grounded for maintaining stability of the IC.

Parts List

R1,R6 = 3M3
R3,R4 = 10K
T1, T2 = 8550, or 187, or 2N2907 or similar
C1,R2 = to be selected for setting up buzzer on time
C2,R5 = to be selected for setting up buzzer on time.
N1---N5 = IC 4049
B1,B2 = Loud piezo buzzers

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