This project presentation describes a mobile phone charger circuit. The circuit uses a step-down transformer, full-wave bridge rectifier, 1000μF capacitor, 7805 voltage regulator IC, and other components. It works by using the transformer to step down 220V AC to 9V AC, the rectifier to convert it to DC, a capacitor to filter it, and the regulator to provide a stable 5V output to charge mobile phones and power small electronics via USB. The group members are Hammad Zaheer and Yawar Abbas, and the charger can operate devices requiring 5V DC input.

1. Project Presentation BS-EE III Semester

2. Mobile Phone Charger
Electronics Devices And Circuits project

3. Group Members
• Hammad Zaheer
Roll No. 16-EE-25
• Yawar Abbas
Roll No. 16-EE-28

4. Application of Mobile charger
• Mobile charger is used to charge mobile phone
• This DC supply can also be used to charge power source for digital circuits,
breadboard circuits, ICs etc.
• Used to operate devices that take 5v DC input.

5. Components
• Step down Transformer
• Bridge Rectifier (four diodes)
• Capacitor 1000 μf
• 7805 voltage regulator IC
• LED
• 1000 Ω
• USB female pin
• Wires

6. Circuit Diagram

7. Working
• This circuit mainly consists a step down Transformer, a Full wave bridge
rectifier and a 5V voltage regulator IC (7805). We divided this circuit into
four parts:
• (1) Step down AC voltage
• (2) Rectification
• (3) Filtration
• (4) Voltage Regulation.

8. Working cont.
• (1) Step down AC voltage
• As we are converting 220V AC into a 5V DC, first we need a step-down transformer to
reduce such high voltage. Here we have used 9-0-9 1A step-down transformer, which
convert 220V AC to 9V AC. In transformer there are primary and secondary coils which
step up or step down the voltage according to the no of turn in the coils.
• Selection of proper transformer is very important. Current rating depends upon the Current
requirement of Load circuit (circuit which will use the generated DC). The voltage rating
should be more than the required voltage. Means if we need 5V DC, transformer should at
least have a rating of 7V, because voltage regulator IC 7805 at least need 2V more i.e. 7V to
provide a 5V voltage.

9. Working cont.
• (2) Rectification
• Rectification is the process of removing the negative part of the Alternate
Current (AC), hence producing the partial DC. This can be achieved by using
4 diodes. Diodes only allow current to flow in one direction. In first half
cycle of AC diode D2 & D3 are forward biased and D1 and D4 are reversed
biased, and in the second half cycle (negative half) Diode D1 and D4 are
forward biased and D2 and D3 are reversed biased. This Combination
converts the negative half cycle into positive.

10. Working cont.
A full wave bridge rectifier component is available in the market, which consist that
combination of 4 diode internally. Here we have used this component.
AC DC

11. Working cont.
• (3) Filtration
• The output after the Rectification is not a proper DC.We don’t need that
pulsating output, for this we use Capacitor. Capacitor charge till the
waveform goes to its peak and discharge into Load circuit when waveform
goes low. So when output is going low, capacitor maintains the proper
voltage supply into the Load circuit, hence creating the DC

12. Working cont.
Before filtration After filtration

13. Working cont.
• (4) Voltage Regulation.
• A voltage regulator IC 7805 is used to provide a regulated 5v DC. Input
voltage should be 2volts more than the rated output voltage for proper
working of IC, means at least 7v is needed, although it can operate in input
voltage range of 7-35V. Voltage regulators have all the circuitry inside it to
provide a proper regulated DC.

14. Working cont.
Before regulation After regulation
• Then we connected the output of the voltage regulator to the USB female
pin from there we can connect it to cell phone.

15. Implemented circuit