2B-MOBILE CELLPHONE CHARGER
THE SPECIALITIES OF PROJECT
Now a days the use of mobile cellphone has increased but battery of mobile cellphone get discharged after 5 or 6 hours. To charge the battery AC supply is required. When a person is out station or is traveling then it becomes difficult to charge the cellphone. This problem is solved by this project.
TECHNICAL DESCRIPTION AND WORKING OF THE PROJECT
This project has been developed and tested by our readers and sent to the “T.V.Engineers Technical lab” for publication in the book. The spare parts and PCB of the projects published in the series of our book publication or available in the market. The information of project code is given in the first and last page of the books.
When a mobile cellphone is charged at slow rate then 100mA current is required from source to charge the battery. For this purpose a 12V battery with 8pen cell is sufficient. The current available is about ——- . Normally to charge the battery of mobile cellphone a battery of 3.6-6V DC with 180-200mA current is required. In this project IC 555 is used , its control voltage at Pin No.5 is kept constant at 5.6V by zeener diode ZD1. The voltage at Threshold Pin No.6 is adjusted by preset VR1. The trigger voltage at Pin No.2 are controlled by preset VR2. When cellphone is connected with circuit for charging at that moment the voltage at trigger Pin No.2 should be less than 1/3 Vcc. This puts ON the flip-flop inside IC and high voltage are obtained from output Pin No.3. When the battery is fully charged the voltage at trigger Pin No.2 are increased. This makes flip-flop in OFF position and stops the battery charging. The Pin No.6 of IC get reference voltage( 2/3Vcc) is set by VR1. The charging current is increased by transistor T1 (SL100). The LED1 is connected inside circuit for calibration of cut-off voltage. This LED monitors the charging voltage and when battery is fully charged, it automatically goes off.
PRECAUTIONS WHILE MAKING THE PROJECT
- The battery used for charging of mobile cellphone should provide minimum of 100mA of current. There may be some difference in the charging current of different cellphones.
- The ON/OFF switch and preset should be of good quality.
- Use IC base for the IC.
While assembling the project check the components to be used and use proper value of components.