The life of the cooler pump increases with this project.  It can work for a longer period without getting heated.  The main attraction of the project is that it puts the cooler pump ON/OFF automatically at proper time.  It also give relief of adding water in the cooler frequently.





This project is boon for the cooler pump.  Cooler pump takes water from lower level to higher level and wet the grass in the cooler’s net.  Once the grass is wet it does not make much difference in the temperature of room for 5 to 7 minutes.  Thus the water poured in the cooler can be utilies for longer time.


With the use of this circuit the pumps runs for 2 to 3 minutes and stops working from 5 to 7 minutes.  Thus the pump is not heated, water remains in tank for longer period and although the cooler will work for 12 hours but pump will run for three hours.


Switch S is connected in the circuit which slects two positions day and night.  In the day time when it is hot and weather is dry put the switch in day position.  Because in day time due to temperature and dry weather the water in the grass gets dry up.  The switch in the day position the pump will remain OFF for four minutes.  In rainy or cold season keep the switch in night position.  In this position the pump will remain OFF for 8 minutes.

In this project the popular timer IC NE555 is used.  Pin no. 4 & 8 of IC are given positive supply whereas pin no. 1 is given negative supply.  The capacitor C4 220mfd/25V is charged by D4 [IN4007] and R2 [1ME].  But it is discharge by R4, R5 and diode D3 connected at pin no. 7.  From output pin no. 3 of IC NE555, a NPN transistor BC547 is connected which operates the relay.  Connect the pump with relay as per the circuit diagram.  In the power supply section of the circuit a 9-0-9V, 250mAmp step down transformer is used.




  1. Use IC base for the IC.
  2. Use relay of good qualities.
  3. Check all connection before giving supply to the circuit.
  4. Take care that there is not shorting on PCB while soldering the components.