This project is more simple and attractive from all the water level indicator projects.  With this project every member of the family can find out the water level in the tank.  The water level is indicated in english.  The common cathode display has been used in the project.




This project can be used in water tank or any other types of fluids, which are not active and combustible.  In this circuit CMOS IC2  CD4001 which is a quad NOR gate is used.  IC1 CD4055 is a 7 segment decoder and display driver IC.  This can display some english letters and 0 to 9 numbers.  BCD codes are given in the table which gives different types of display.  These BCD codes are produced by NOR gate [CD4055].  Because there internal connections are made by the sensing probes in the water.  The pin no. 14 of IC2 CD4001 is given positive supply and pin no. 7, 8 are grounded.  The pin no. 3, 4, 10 of this IC are connected pin no. 3, 5, 2 of IC 1 [CD4055] respectively.  The output pin no. 11 of IC2 is connected with the base of transistor T2 [BC548]. This transistor T2 along with the T1 display the letter E & F.  These transistor black out the unnecessary segments from the 7 segment display.  These transistors are used because both these letters are not available for display in ICs1 [CD4055].  The letter E is framed by the b & c segment.  When this IC makes the letter P then at that time letter F is framed by the black-out of segment b.  Four nos. of input sensing probes are installed in the tank as given in the diagram.  The current consumption is very less.  The circuit works with 9V supply.




  1. Use IC base for the IC.
  2. Take care that PCB does not get shorted while soldering the components.
  3. First of all, check all components so that all components are OK.
  4. Check the cathode and anode terminals of diode while soldering it.
  5. Use good quality preset.
  6. Carefully soldered the collector, base and emitter terminals of transistor.