Most of the mobile phones these days can be charged from a USB port with an output of 5 v DC. now u can charge your mobile phones anytime anywhere using this simple portable usb charger.

## Step 1: Components Needed

The components we will use are:

One - LM7805
Two - 1μf Capacitor
One - 5 Ω 3 Watt Resistor

## Step 2: The Circuit Diagram

The circuit is very simple and can be soldered very quickly on a small general purpose PCB. The components from left to right are, 7805 , 5.4 ohm resistor and two 1uf capacitors.
I have sketched the layout along with the 7805's pin configuration. It is a fairly simple and straight forward circuit. The positive input is connected to both the pin one of the 7805 and the positive of the first capacitor . The pin three is connected to the positive of the capacitor and one end of the resistor, this forms the positive 5 v output. This completes our positive side. For the negative we connect all the negatives together - the negative in, negative out, negative of the first capacitor, negative of the second capacitor and pin 2 of the 7805.

## Step 3:

The output can be taken as a wired output or a USB port can be directly mounted on to the PCB. Here you see the completed board. I have drilled two holes to secure the port later. The red and the black wires are the input wires.

## Step 4:

<p>good work, but the biggest question is.......<br>From where you will get input voltage, since you need DC voltage little more than 5 volt say 8-12 volt.</p><p>If this circuit were a complete then it would be nice one.</p>
from a 9v dc battery!<br>u may use a battery cap to make connection with battery easier!
<p>goood work.. keep it up</p>
<p>What's the 5.4Ohm resistor for? There is no need for that.</p>
By varying the resistance of the resistor between 5 and 15 ohms the output current can be reduced or increased as per requirement. While doing this ensure that the resistor you use is rated at 3 watts or above and that the 7805 has a very good heat sink and that it doesn't overheat. A small amount of heat however is quite normal.
<p>Ah yes, ... well, no.</p><p>If you design something with an USB connector, it should behave like a powered USB device. With a USB device, the voltage is stable. With your design, the voltage drops when the current consumption increases. That's just the opposite A 7805 is used for. </p><p>If you need a current limiting resistor in your charger put it there. Anyway, for anything more sophisticated than a NiCd, you should use a better charger design.</p><p>Your remarks about the heat sink should go into the instructable together with the according thermal design formulas. And you should state the min/max supply voltages.</p>
<p>thts awsm.......but need some improvement</p>
<p>280x158px is way too small to see whats going on, a better size would be like the components pic(1600x900px) in step 1, other than that cool idea.</p>