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.
Remove these adsRemove these ads by Signing Up

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.

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

steven675 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.

erikassxx3 months ago

It's should look like this:

rexxxdavid4 months ago
how long a 9v battery can charge a usual cell phone?
Like2lego7 months ago
What happens when I do not put in the capacitators?
Hashimsyed10 months ago
We are applying dc source to circuit and capacitors are open for dc. so, how the circuit is running fine????please reply..
imx311010 months 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?
jrv41110 months ago
adityam12 months 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????
sneekhra1 year 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
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!
Themaxim1 year ago
Does it work on ipad
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,
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)?
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?
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.
One.3 years ago
hey thanks for this, I made one and I also came up with a better idea:
evil usb charger plans! mwahahahahahahahaha ; ).bmp
wladicus One.1 year ago
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?
emaylas One.2 years ago
cani change the battery x4 aa bateries to 9volts batt ?
The 7805 can take anything from 6 volts to 35 volts
One. emaylas2 years ago
yes. it doesn't really matter, but if you want to use the battery's full "energy", this is not a very good way to make one. the 5 volt regulator just wastes the other 4 volts as heat, so its as if you were charging something that was 9 volts instead of 5.
its really good for a quick charge, though, but be sure not to leave the battery in when you aren't using it.
emaylas One.2 years ago
it works ?? ...
One. emaylas2 years ago
hmmm. very much the same question, but with less question marks!
yes! of course!
Euticus One.2 years ago
Some regulators REQUIRE a cap on the output to guarantee stability. Check the datasheet.
One. Euticus2 years ago
then this wiring diagram would REQUIRE you to buy a stability guaranteed regulator ; )
not gonna work, 6 volts is too low for a 5 volt regulator, epsicialy once the batteries get down to 4 volts
that picture was supposed to have a 9 volt battery but I must have messed up somehow. oh well!
emaylas One.2 years ago
it works ????????
froggyman One.3 years ago
While that will work, it will not give you protection from voltage jumps. Thats what the caps are there for.
For a 6 volt input, where would capacitors go? and what type of caps are needed?
It doesn't really matter what caps you use, in reality you don't even need them... they are just a nice to have as a little "surge protector" for the voltage as the caps help regulate this voltage by storing and releasing when necessary. Plus they are cheap and could potentially save the device you have hooked up to this.

You can *NOT* use a 6 volt input for the 7805 5V regulator as that regulator needs to have atleast 7 volts to work well. I'm not sure what input you are planning to use, but depending on your space something like two 6v lantern batteries in series (have one of the batteries positive + terminal connected to the other batteries negative - and use the remaining for your power of 12 v ) or you could use 6-8 AA batteries for your power source for the regulator.
ik1102 years ago
Iam very much interested in making the charger but iam a totally novice when it comes to PCB and itching and cutting them nor I have any knowledge of caps or resistors... can any one load video of the entire process please >>>>
m1s73r ik1102 years ago
So, first of all I think making this charger isn't a good idea for you, because this is a little bit harder as maybe other Projects. You should start with something easier, with less electric parts.

The PCB isn't really necessary because you can also use a breadboard or something. I use a perfboard and it works great.

Caps (capacitors) can store energy for a time, such as your computer does.
Resistors are like a dam, they stop the energy or convert it to heat.

I hope I could help you a little
BTW, the PCB makes it easy to connect stuff and is worth the extra minute that it takes to Dremel the board and drill holes in it.
idsonic ik1102 years ago
pls can i get every thing about this project? including the write up
idsonic ik1102 years ago
pls can i get every thing about this project? including the write up
bbeyzat2 years ago
where to find the board or what else we can do
Radio shack

Get More Out of Instructables

Already have an Account?


PDF Downloads
As a Pro member, you will gain access to download any Instructable in the PDF format. You also have the ability to customize your PDF download.

Upgrade to Pro today!