Picture of Portable USB Charger (Version 2.0)
The project name says it all. It is a device that will charge things like Ipods, PDAs, other other devices that plugs into a USB to charge.
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Step 1: Supplies

Picture of Supplies
The parts needed for this project are all in the second picture.

You will require:

LM or MC 7805 +5VDC Voltage Regulator
Type-A Female USB Port
100 UF Electrolytic Capacitor 10-50v
0.1-0.5 UF Capacitor  6-50v (any type would do)
150-160 ohm Resistor (optional)
9V Battery clip
2.2V 20mA LED color of your choice (optional)
Unprinted circuit board
ON/OFF Switch (optional)

These parts can be easily purchased at your local electronic store, like Radio Shack. Or you can buy them online at:


USB port:

100 uF Capacitor:

0.1 uF Capacitor:

Step 2: The Circuit Board (Simple way)

Picture of The Circuit Board (Simple way)
The following picture shows the prepared PCB before putting in the necessary components.

What your looking at is the underside of a PCB with the copper foil facing you.
The gray line represent the location where the cut is to be made. Make sure that the 3 sections are electrically isolated (do not conduct to each other).  If you have a dremel tool, you can score the copper cladding with a cutting wheel.

The black dots are the locations where holes are to be drilled.

Step 3: Attching the components

Picture of Attching the components
Watch the polarity when putting in the components, especially the regulator, or it will get very hot and burn out.

*BEFORE plugging in your USB device to this charger, test the charger's output using a multimeter. Hookup the 9-volt battery and measure voltage output, it should be between 4.8-volts to 5.2 volts.

*If the black light comes on when you plug the iPod into the charger, that means the charger is working correctly, and if the black light doesn't come on after 3 seconds, remove the iPod from the charger immediately, and recheck your charger for shorting or incorrect polarity.

*If you double checked the output and still no luck, try attaching a resistor bank described in the comments below to the data lines.
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I made the circuit and Nokia does not work

afezi1 month ago

i'm willing to build a buck-boost converter (5v output) for my thermoelectric generator. For now i'm still cant design it. So the alternative way for me is to build a boost converter and make sure input of those converter doesnt exceed 5v. My question, can i use this circuit as the boost converter?

Cyradill1 month ago
Can you use a rechargeable 9V battery? As I plan to have the battery hooked up to a solar panel as part of my AS level DT project
umaryasin21 made it!2 months ago

this is what i made on wiro board

adityam1 year ago
Hello SIR ,
Can u tell me what is highest voltage that can i give as an input to this charger and who many cell phones can it charge is 9 V is supplied as input????

35 volt max DC

Vanel02 adityam2 months ago

Input voltage of 7805 regulator is 5V-18V and output voltage is 5V (4.8V-5.2V). regulator use to maintain the output voltage so this circuit can be use as a phone charger for motorcycle. am i right sir?

Vanel02 adityam2 months ago

Input voltage of 7805 regulator is 5V-18V and output voltage is 5V (4.8V-5.2V). regulator use to maintain the output voltage so this circuit can be use as a phone charger for motorcycle. am i right sir?

Look for the Datasheet of the regulator you have.

Immanoj92 months ago

hey! how can i do same with this kind of 6 volt 4.5Ah battery

USB Female hubs have 4 prongs as you've probably noticed. the right and left ones are ground and power respectively. The middle ones are the Data + and the Data -. for 99% of the phones out there you don't need to attach anything to the data ports. Apple products however have a strict security feature that will not allow one to use home made chargers.. you can hack this by "tricking" your apple product into thinking that it is actually plugged into a laptop. This can be done by splitting the power from the Voltage Regulator into two wires and attaching them to BOTH of the data ports WITH 100 ohms resistors (on each port). It's IMPORTANT that you use the 100 Volt resistors because you can blow your iphone/ipad 's usb port otherwise and never be able to charge it again. Good luck with your chargers!

you are so hot it works

Mitva6 months ago
I am getting a proper 5V output
But i am not able to charge my iphone 5s
Please help me out
kittt7 months ago
As an Electrical engineer, I concur with @wildsevohn that the design, though able to produce a 5V output and probably be able to release some good amount of current juice(few hundreds of mA), it's definitely NOT one of the best( in terms of safety & efficiency) method to charge your phone.
Probably we need to look into designs of higher efficiency, for eg by Ladyada and others on Google. Since a voltage regulator, in theory (and in practice) is NEVER as efficient as a switched mode power supply (SMPS) , this design definitely needs a reboot! Do take a look a Ladyada's design. Search for her name in Instructables.

Anyway, thanks for the author for putting up this tutorial! We all learn from one another :)
willdevohn7 months ago

i'm a appliance technician, 4 me this is a worst charger that i saw., coz if you see the diagram & try it to yourself oh my god this is not 100% effective & it will cause damage on your unit.

DerDok8 months ago

can I just reverse the 7805? mabe use diffrent restors to cut the voltage down a volt? The RCR123A battery is suppose to be kina fussy about charging.

DerDok8 months ago

I love this circuit!!!, its really close to what im trying to build, I am trying to reverse the voltage, so it charges a 3.0 v camera battery which charges at 4.2 @ 250mA, maybe put a LED across that turns on when battery reached 4.2v so you know its charged and all the voltag goes to the LED and protects the Lithium-ion battery. Its a rechargeable R123A. Any thoughts, help, sugestions?

sneekhra2 years ago
hello sir plss give me the details of the changes i have to do if i replace the 3.7 volt battery instead of 9v battery to get a good charger

You can't use a 7805 any more. You'll need a booster circuit because this thing is only to drop down the voltage. A booster circuit is able to push the voltage up from 3.7v to 5v.

ehm and these you can find on amazon or radioshack i think. Just search "5v booster circuit". If you have an iPhone, make sure that the circuit is prepared for iDevices (comments, description)

Themaxim2 years ago
Does it work on ipad

Not enough Power. An iPad needs about 2.1 Amps. This one brings only 1A.

krisjaanis9 months ago

Hi! I made this project, but i have a problem... I charge my Nokia 630 then i disconnect USB. but my battery level drops very fast, after i disconnect USB!

Heeelp me! what's wrong?

krisjaanis9 months ago

Can i use L7805CV?

yooooo108910 months ago

Works just fine.

faissal__10 months ago

Is this Rechargeable ? Yes-Then ok! No-Then, what changes would have to do in this circuit ? Explain Please. Thanks in advance !!

kuukske10 months ago

Quick question: why are you using a electrolytic capacitor on your input voltage? Will a ceremic capacitor also work?

Yash77311 months ago

i am facing a serious problem..... Even after connecting the components with recommended values and with right polarities my phone instead of charging gets discharged with a constant rate..... what should i do...

Yash77311 months ago

i am facing a serious problem..... Even after connecting the components with recommended values and with right polarities my phone instead of charging gets discharged with a constant rate..... what should i do...

There is mistake in the printed circuit. Here is the fixed and reduced form. It include a LED and switch, too.

steven676 years ago
I dont really want to etch a board or drill holes is three any other option

Long time, I know but if I don't have a board to play with, I solder everything and use hot glue to make sure everything is isolated. Hardly a final product but it gets some use as I learn.

erikassxx1 year ago

It's should look like this:

rexxxdavid1 year ago
how long a 9v battery can charge a usual cell phone?
Like2lego1 year ago
What happens when I do not put in the capacitators?
Hashimsyed1 year ago
We are applying dc source to circuit and capacitors are open for dc. so, how the circuit is running fine????please reply..
imx31101 year ago
Hello sir,
I have a doubt regarding PCB etching provided.
The 7805 has the 2nd terminal as ground and 3rd terminal as output but the design given seems to have 2nd terminal connected to output and 3rdterminal to ground(As it seems to be connected to -ve terminal of battery). Can you please provide an explaination where I could've gone wrong in the interpretation?
jrv4111 year ago
I also built the same, and after 5-6 secs my phone shows warning msg "NOT CHARGING! BAD CONTACT". Problem is not with the cable as i have already checked. And I don't know what's the problem with my ckt. Plz help!
If a capacitor is "Leaky" or damaged then a short circuit or intermittent short circuit to ground condition is created and the 5 volts at the regulator output will also be grounded and the output would drop to 0 volts.
If the capacitor at the output has an intermittent or 'slow leak' then that could why after 5-6 seconds your phone shows a "NOT CHARGING!" message, because at that moment the capacitor has shorted to ground and the output voltage has dropped to 0 volts.
That is one quite likely answer. These conditions are sometimes tricky to find with voltage measurements if the capacitor does this only sometimes. The best solution is to replace the capacitor or remove it completely and see if the charging is restored.
Hope this helps,
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