A completely charged battery is needed particularly when your range in the nearest relay station increases. Here’s an easy charger that creates the cellphone battery within two to three hours. Basically, the charger is a current-limited voltage source. Usually, cellphone battery packages require 3.6-6V DC and 180-200mA current for getting. These usually contain three NiCd cells, each having 1.2V rating.
Existing of 100mA is enough for getting the cellphone battery at a slow rate. A 12V battery including eight pen cells gives sufficient current (1.8A) to charge the battery connected across the output terminals. The circuit also monitors the voltage degree of the battery. It automatically reduces the getting process whenever its result fatal voltage increases over the predetermined voltage level.
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| Circuit diagram of mobile charger |
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
Circuit Operation:
Timer IC NE555 is utilized to charge and monitor the voltage level within the battery. Control voltage pin 5 of IC1 obtains a reference voltage of 5.6V by zener diode D1. Threshold pin 6 is which has a voltage set by P1 and trigger pin 2 is having a voltage set by P2. In the event the discharged cellphone battery is attached to the circuit, the voltage presented to trigger pin 2 of IC1 is below 1/3Vcc so because of this the flip-flop inside IC is turned on to look at output pin 3 high. Once the battery has been fully charged, the output terminal voltage enhances the voltage at pin 2 of IC1 higher than the trigger point threshold.
This switches over flip-flop along with the output goes low to terminate the charging process. Threshold pin 6 of IC1 is referenced at 2/3Vcc set by P1. Transistor Q1 is employed to further improve the charging current. Valuation on R3 is very important in giving the required current for charging. While using given valuation on 39-ohm the charging current is about 180 mA. The circuit could be constructed with a small general-purpose PCB.
For calibration of cut-off voltage level, utilize a variable DC source of energy. Connect the output terminals in the circuit on the variable energy set at 7V. Adjust P1 in the centre position and slowly adjust P2 until LED (D2) is triggered, indicating low output. LED should activate in the event the voltage in the variable energy reduces below 5V. Enclose the circuit in a tiny plastic case and rehearse suitable connector allowing you to connect on the Circuit diagram of mobile charger.
