Schematic Reference

Mobile Travel Charger Circuit

Here is an ideal Mobile charger using 1.5 volt pen cells to charge mobile phone while traveling. It can replenish cell phone battery three or four times in places where AC power is not available. Most of the Mobile phone batteries are rated at 3.6 V/500 mA. A single pen torch cell can provide 1.5 volts and 1.5 Amps current. So if four pen cells are connected serially, it will form a battery pack with 6 volt and 1.5 Amps current. When power is applied to the circuit through S1, transistor Q1 conducts and Green LED lights.

Most of the Mobile phone batteries are rated at 3.6 V/500 mA. A single pen torch cell can provide 1.5 volts and 1.5 Amps current. So if four pen cells are connected serially, it will form a battery pack with 6 volt and 1.5 Amps current. When power is applied to the circuit through S1, transistor T1 conducts and Green LED lights. When T1 conducts T2 also conducts since its base becomes negative. Charging current flows from the collector of T1. To reduce the charging voltage to 4.7 volts, Zener diode ZD is used. Resistor R4,and R5 allows 20 mA charging current. If more current is required, reduce the value of R4 to 100 Ohms so that with in 20 to 30 minutes battery will become fully charged. Points A and B are used to connect the charger with the mobile phone. Use suitable pins for this and connect with correct polarity.

Circuit diagram :

Mobile Phone Travel Charger Circuit Diagram

Parts:

R1 = 1K
R2 = 470R
R3 = 4.7K
R4 = 270R
R5 = 27R
C1 = 100uF-25V
D1 = Green LED
D2 = 4.7V/1W Zener
B1 = 1.5Vx4 Cells
S1 = On/Off Switch
Q1 = BC548
Q2 = SK100

The circuit comes from here.