Cellphone Charger

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Mobile Cellphone Charger

Heavens Light is Our GuideRajshahi University of Engineering and TechnologyProject Presentation

Course Name : Electronic Shop PracticeCourse No: EEE-300

Welcome To Our Presentation

Developed By :Imam Mehedi Hasan (101037)Rakib Hossain (101039)Md. Shakhawath Hossain (101043)Portable Cellphone ChargerProject Supervisor:Dr. Md. Masud RanaAssistant ProfessorDepartment of EEE, RUET


While travelling charging of mobile battery is great problem because power supply source is not generally accessible.A fully charged battery becomes necessary especially when your distance from the nearest relay station increases.Here is a simple project using very common electronics components for charging mobile battery using AA cells & 555 timer IC which IC is an integrated circuit (chip) used in a variety of timer, pulse generation and oscillator application.Moreover by successfully completing such a project, we will understand the full process of what it is to design and manufacture an electronic device.

Introduction Cellphone chargers are nothing but AC to DC converters. They take an input of 220 volt AC and give an output voltage around 5Volt DC. Basically, the charger is a current-limited voltage source. Generally, cellphone battery packs require 3.6-6V DC and 180- 200mA current for charging. Current of 100mA is sufficient for charging the cellphone battery at a slow rate. Phones have rechargeable batteries inside which need to be charged with a DC voltage (slightly higher than the battery voltage). Simple phone chargers provide this DC voltage. Ours is the one kind of this. It is a universal mobile charger so we can connect any mobile connector. For example. If we want to build a charger for Nokia then we have to install a Nokia pin or if we want to connect a Sony Ericsson mobile we can install Sony charger pins at the output.

ApparatusApparatusValuesR1390 R2680 R339 /1WR427 KR547 KR63.3 KR7100 /1WVR1, VR220 K

ApparatusValuesC10.001 FC20.01 FC34.7 F/25V


ApparatusApparatusValuesIC1NE555 timer ICT1SL100ZD15.6 V/1WSW1On/Off SwitchBattery12 VLED1

Circuit Diagram

555 Timer IC (Pin diagram)

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 ZD1.Threshold pin 6 is supplied with a voltage set by VR1 and trigger pin 2 is supplied with a voltage set by VR2.When the discharged cellphone 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. This switches off the flip-flop and the output goes low to terminate the charging process.Threshold pin 6 of IC1 is referenced at 2/3Vcc set by VR1. Transistor T1 is used to enhance the charging current.Value of R3 is critical in providing the required current for charging. With the given value of 39-ohm the charging current is around 180 mA.Working Principle

Experimental Setup

ResultAt lab, the circuit was tested with a Nokia make cellphone battery rated at 3.7V, 320 mAH. The charging current measured was about 200 mA. The status of LED1 is shown in the table.

LED StatusLoad across the OutputLED1No Battery ConnectedOnCharging BatteryBlinkFully Charged BatteryOff

Features and Benefits

Charger holds enough power to recharge your mobile devices.Compatible with any model of cell/smart phones.Charge cell/smart phone for up to 12 hours of additional talk time.Color LED indicates charging status.Automatic turn off charging when charging is complete.Mobile can be charged anywhere where power is not available.12V battery is rechargeable.



End Of Presentation