This project is that of easiest timer circuit. This can be used in any of the electronics projects connected with toys fridge or in factory equipments. Time can be increased or decreased by this timer.
TECHNICAL DESCRIPTION AND WORKING
This project has been developed and tested O.K. in our TV Engineers Technical Lab. The components and PCB used in the projects published in our books are available for sale at resonable price.
This project is based on IC555. This is a popular IC and it can be used in digital and analog circuits. It has been used as a monostable multivibrator circuit. This circuit works on 6V DC. Time can be adjusted from 1 second to 5 minutes by changing the position of pot [1M]. The duration of the time depends upon the charge/discharging of 100mfd condenser. This condenser is charged through the pot [1M] and 10K resistance. As soon as supply reduces to 1/3 of its normal value pin no. 6 of the IC get triggered and output at the pin no. 3 becomes low. Due to this relay stop working and equipment connected to the relay can be put ON/OFF. The duration of timer can be increased by changing the value of 100mfd condenser. A LED has been used to indicate the high or low position of output at the pin no. 3.
PRECAUTIONS WHILE ASSEMBLING THE PROJECT :-
- Used a relay of higher rating with good contacts to handle heavy loads like Air Conditioner.
- Before soldering the transistor check its base, emmiter and collector by multimeter.
- Take care polarity of the condenser connected at pin no. 6 of IC555.
- IC should not be soldered directly on the PCB because parts can be damaged due to leakage of electric current from the soldering iron.
LIST OF COMPONENT
PCB [Code 5TP06]=1
10K =2, 22K =1, 4K7 =1, 1M POT=1
0.01 =1, 4.7mfd/16V=1, 100mfd/16V =1
IC555=1, BC548=1, IC BASE [8 Pin]=1, RELAY=1
DC Supply 9V =1
One Bulb [100 W]=1