This document provides instructions for building a portable USB charger using common electronic components. It lists the necessary components including a LM7805 voltage regulator IC, resistors, capacitor, LED, switch, USB jack, PCB, wires, and 9V battery. It explains that the LM7805 IC regulates voltage to a constant 5V and provides up to 1A of current. It also gives details on USB charging standards, noting that devices require 5V power on the Vcc and Gnd lines to charge while the D+ and D- data lines connect to 5V through 100K resistors to enable fast charging.

2. COMPONENTS NEEDED:
1) LM 7805 (5V voltage regulator IC).
2) 100 K resistors (1/4 watt 2 nos.).
3) 1 K resistor (1/4 watt).
4) 100 uF capacitor (16V or more).
5) Green LED (3mm)
6) Soldering iron and solder wire.
7) Switch (SPST).
8) USB type A female jack.
9) PCB.
10)Connecting wire.
11)9V battery.
12)PCB Terminal.

3. RESISTORS:
1 K
100 K
CAPACITOR
100 uF
LED

4. LM 7805 IC (5V voltage regulator)
1) LM 7805 is a linear voltage regulator IC.
2) It can regulate a voltage to 5V DC with an input
voltage ranging from 6V to 37V approx.
3) It gives a constant current of 1A as output.
4) It is a very stable IC and is perfect for a portable
charger.

5. LM 7805 PINOUT:

6. USB charging is currently the most universal method of
charging an electronic device. This workshop details the process of
construction of a cheap and simple portable USB charger which can
be used to charge cell phones, mp3 players, cameras, etc and almost
any device.
USB normally contains 4 lines – Vcc(+5V), Data-(D-),
Data+(D+) and Gnd(Ground) . The Vcc and the Gnd line are used to
power a device and the D- and D+ line are used to transfer data
between the host and the device.
INTRODUCTION

7. The USB is expected to maintain 5V within a
range of ± 0.5V and provide current of 100mA,
unless requested for more current. To build a USB
charger all you need to do is build a circuit that
outputs current within the USB specification.
A cell phone could only charge if the current is
1A approx. and the voltage is 5V . Therefore the data
pins on the USB are connected with 100K resistors to
the 5V supply. This tells the device that the charger is
connected and the device charges normally
otherwise the device charges slowly.
ABOUT USB CHARGING

8. USB PINOUT:

9. CIRCUIT DIAGRAM

10. THE END