Water level Controller

Water level Controller using CD4001

Working details :

1. Motor operates only if, Reservoir tank is not empty.  If it empty while running motor pump, it is switched off

2. When water level at Low level indicated, Motor starts ( If also, reservoir is not empty) 

3. When water level reaches High level, Motor stops.

Additional Features:

1. Circuit is compensated for, false switching due to ripples in water tank.

2. Only DC, small voltage is used in circuit and sensing leads.

3. Low current (Serried through 1M ohm to 100 M ohm resistance) sensing

4. Sensing by grounding method is used, so no charge accumulation any where

5. LED indication of  Hi, Low, Reservoir Low, Motor status.

6. Manual Operation of Motor using parallel switch. 

Circuit Diagram

Truth Table

Hi Level    Low Level   Low level (R)  Motor

False         True         False          ON

After Motor starts, it continue to be ON

False        False        False           ON

Motor continue to run, till the situation as below

True          False         False          OFF

Or in a situation, if the Reservoir is go empty

False      False          True             OFF

Components and Board

I started assembling this circuit today. I used 10 M resistors for all 3 resistors.

Tested it with water taken in a glass. Worked good. 

Found that there is no problem even in case the two sensor leads touch directly each other.  It is becouse, of the High value resistor (10M) limits the current through circuit.  

Circuit was done in a general purpose PCB, with IC base. To get 9V supply, a regulator IC

was used. I tested the circuit with an LED (Green) at the pin 11 of the IC, with a resistor in series.

Testing connections  before giving power supply

The Circuit worked good, with 30 meters of cable routed to the Top tank.  Water Level Controller fixed  near the water pump.  Additional indicator LED s were placed on front panel to visual indication of Motor ON, and Power ON for the controller circuit.  The same cable was routed for bottom reservoir tank.  So the project is successful, as far as it is completed and functioning well.