Introduction: Portable USB Charger (Version 2.0)

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.

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.

Step 4: The Printed Circuit Board

Picture of The Printed Circuit Board

The first picture is the circuit that is to be etched onto the PCB, the second picture shows where everything should go.

*Your looking at the side with the copper foil, so watch the polarity when putting in the components

Step 5: Printed Circuit With LED

Picture of Printed Circuit With LED

This design incorporates a LED which will be lit when the device is turned on.

Step 6: Adding the Switch

Picture of Adding the Switch

Add a switch to this circuit is very simple, it'll save a lot of battery when you turn it off than just leaving it on idle. You can attach the switch anywhere BEFORE the capacitor (if you did not use a capacitor, then before the 7805).

Step 7: Done!

Picture of Done!

Now that you've finished building your own USB charger, all you have left to do is to put it in a nice box and show it off to your friends!


dd007 (author)2017-02-13

what r the ways 2 boost d charging rate???

dd007 (author)2017-02-13

why do v use capacitors??

1 Amp is not good enough for a phone charger...i have very cheap china car charger rated at 5 volt and 2 Amp the charging is fast and quick better than original samsung charger. And of course the device is dirt cheap as always...I am starting to believe what China these days

imx3110 (author)2013-06-20

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?

PabloAB (author)imx31102015-08-28

You are right, this PCB is dangerously wrong:

HalfS (author)2015-06-06

this circuit is able to imput charge in the battery for reacharger?

skumar231 (author)2015-04-21 what and Make by Own Best of Luck

jannier.molina.7 (author)2015-02-26

I made the circuit and Nokia does not work

afezi (author)2015-02-25

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?

Cyradill (author)2015-02-20

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! (author)2015-02-14

this is what i made on wiro board

adityam (author)2013-04-23

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????

umaryasin21 (author)adityam2015-02-14

35 volt max DC

Vanel02 (author)adityam2015-02-08

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 (author)adityam2015-02-08

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?

flostar3000 (author)adityam2014-07-17

Look for the Datasheet of the regulator you have.

Immanoj9 (author)2015-01-28

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

skeletonkey124 (author)2013-01-18

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

Mitva (author)2014-10-12

I am getting a proper 5V output
But i am not able to charge my iphone 5s
Please help me out

kittt (author)2014-09-17

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 :)

willdevohn (author)2014-09-12

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.

DerDok (author)2014-07-30

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.

DerDok (author)2014-07-30

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?

sneekhra (author)2013-03-18

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

flostar3000 (author)sneekhra2014-07-17

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.

flostar3000 (author)flostar30002014-07-17

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)

Themaxim (author)2012-12-23

Does it work on ipad

flostar3000 (author)Themaxim2014-07-17

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

krisjaanis (author)2014-06-23

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?

krisjaanis (author)2014-06-23

Can i use L7805CV?

yooooo1089 (author)2014-06-17

Works just fine.

faissal__ (author)2014-06-16

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

kuukske (author)2014-05-26

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

Yash773 (author)2014-05-01

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...

Yash773 (author)2014-05-01

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...

Väterchen Frost (author)2014-02-03

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

steven67 (author)2009-04-11

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

Shandleyman (author)steven672014-01-15

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.

erikassxx (author)2014-01-13

It's should look like this:

rexxxdavid (author)2013-11-30

how long a 9v battery can charge a usual cell phone?

Like2lego (author)2013-09-11

What happens when I do not put in the capacitators?

Hashimsyed (author)2013-06-20

We are applying dc source to circuit and capacitors are open for dc. so, how the circuit is running fine????please reply..

jrv411 (author)2013-06-09


kaushal.1214 (author)2012-12-18

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!

wladicus (author)kaushal.12142012-12-19

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,

wladicus (author)kaushal.12142012-12-18

1. When you say "I also built the same" are you referring to the author's 7805 circuit or are you referring to the 'car lighter' charging cable idea that I described?
2. In either case - Are you reading an output voltage around 5v DC from the end of your cable that goes into your phone (before you plug it into the phone)?

kaushal.1214 (author)wladicus2012-12-19

I was referring to the 7805 ckt. which author described. and yes i have also checked the output, which is approx. 5v. I'm using 9v battery as input, capacitors of 100uf of 50v n other 0.1uf ceramic type of orange colour.
I also want to know, Is it ok to directly attach the output of 7805 to the phone?

wladicus (author)kaushal.12142012-12-19

If your phone is designed for a 5V charging input then the direct output from the 7805 will work. If the output voltage of the 7805 is around 5v DC and steady (ie. the 7805 is not damaged).
A capacitor of 10uf or greater is sometimes added at the output of the 7805, and sometimes even another capacitor of about 0.1 uf is also added.  The function of the capacitors is to "smooth out" the 5 volt DC input by shunting spurious frequencies to ground. You would need an oscilloscope to actually see these 'spurious' frequencies riding on top of the  5volt DC signal.  They are usually created by the regddulator circuitry or any other nearby high or low frequencies which are always present in today's highly concentrated 'air waves' signal grid.  The larger capacitor shunts or pulls the lower frequencies down to ground potential, and the smaller capacitor shunts the higher frequencies to ground.  Most of the time you can eliminate these capacitors, but if you look at the spec sheets for the regulator you will see their suggested test circuits using capacitors for this purpose.
Capacitors are also used to 'build up' and store electrical charge, but that is not the main function of the capacitors in the regulated circuit design.

wladicus (author)2012-12-18

Did you use a 7805 in this design? - Spec sheet indicates a minimum of 7v input.
4 AA cells = 6 volts DC... so was your regulator a LDO (Low Drop Out voltage) type?

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