Mobile Cell Phone Battery Charger Circuit Using 555 IC

This is a design circuit for Mobile Cell phone Battery Charger. Stops charging when battery is full charged, Portable unit charging of the mobile phone, cell phone battery is a big problem while traveling as power supply source is not generally accessible. If you keep your cell phone switched on continuously, its battery will go flat within five to six hours, making the cell phone useless. This circuit is work using based on 555 IC. This is the figure of the circuit.


Generally, cell phone battery packs require 3.6-6V DC and 180-200mA current for charging. These usually contain three Ni-Cd cells, each having 1.2V rating. Current of 100mA is sufficient for charging the cell phone battery at a slow rate. A 12V battery containing eight pen cells gives sufficient current (1.8A) to charge the battery connected across the output terminals. The circuit also monitors the voltage level of the battery. It automatically cuts off the charging process when its output terminal voltage increases above the predetermined voltage level. Timer IC NE555 is used to charge and monitor the voltage level in the battery. Control voltage pin 5 of IC1 is provided with a reference voltage of 5.6V by zener diode D1. Threshold pin 6 is supplied with a voltage set by P1 and trigger pin 2 is supplied with a voltage set by P2. When the discharged cell phone battery is connected to the circuit, the voltage given to trigger pin 2 of IC1 is below 1/3Vcc and hence the flip-flop in the IC is switched on to take output pin 3 high. When the battery is fully charged, the output terminal voltage increases the voltage at pin 2 of IC1 above the trigger point threshold.

Part:
P1 = 20K
P2 = 20K
R1 = 390R
R2 = 680R
R3 = 39R-1W
R4 = 27K
R5 = 47K
R6 = 3.3K
R7 = 100R-1W
C1 = 4.7uF-25V
C2 = 0.01uF
C3 = 0.001uF
D1 = 5.6V-1W Zener
D2 = 3mm. Red LED
Q1 = SL100

S1 = On/Off Switch
B1 = 1.5vx8 AA Cells in Series
IC1 = NE555 Timer IC