its a pain when your phone battery is low and you have to do some work and there is blackout then how will you charge your phone then you will use this emergency charger which will give a an extended juice for your phone with a 9v battery

so without further lets do this

Step 1: Tools Needed

7805 ic

micro usb cable

9v battery

9v battery connector

and some basic materials

this is all you needed to do this

it costs around 1 $

thats cheap it is

Step 2: Heat Up the Soldering Iron

just cut the usb in hald and connect the each wire as shown above

note before powering your phone with it just take a multi meter and check the voltage it should not excced from 5.2

otherwise your phone may be damage

Step 3: You Are Already Done

that how easy and simple it is to make a emergency charger

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<p>how much charge can the 9v provide?</p>
This can provied from 100 to 500 mah depending on the battery type and juice left and also on the ic if it is 7805ic then 100 to 500mah<br>But if it is a 78l05 transistor then it can give from 500 to 1000mah
Just a small correction, the 78L05 'transistor' is not a transistor at all, it is exactly the same thing as the lm7805, just smaller and in the same package as many small transistors. While it is slightly more efficient than its bigger brother, the 78L05 can only output 0.1 amps, and the lm7805 can output up to 1.0 amps. Since a phone can, theoretically, draw over an amp, using the 78L05 is not a very good idea.
<p>The LT7805 &quot;cuts&quot; higher Voltages then 5V off. So you will lost 9-5=4V </p><p>The current will be the same as before (minus the losses)</p><p>Example: 9V-Battery with 1000mAh (1Ah)</p><p>Energy stored in Battery: 9V*1Ah = 9Wh</p><p>Energy after LM7805: 5V*1Ah = 5Wh (you still have to subtract the losses)</p><p>Capacity in the smartphone battery (average Voltage = 3,7V ): 5Wh / 3,7 V = ~1,35Ah = 1350mAh</p><p>In real life you will have higher losses so maybe it will restore 1000-1200mAh</p><p>But most of the energy will be transformed into heat so it's not very efficient</p><p>It's more efficient to use a Switching Regulator instead of a Linear Regulator</p>
<p>thanks for the explanation . I will plan on my phone lasting one hour after I charge it with the battery.</p>
Thanks bro for your help and by the way i am only 15 and i have telled him what i have dicovered with this project sorry for any wrong information<br>And also thank you for telling me this and i will try to make a project with more efficient this month<br>

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