Introduction: YAN9VUSBC

Picture of YAN9VUSBC

(Yet Another 9 Volt USB Charger)

Step 1: Parts and Testing.

Picture of Parts and Testing.


5v regulator (Lm7805)
Female USB port
Braided wire (20g)
Used 9v battery (Walgreen's brand)
5 minute liquid epoxy
Non-conductive epoxy putty

The circuit design is from All I did was add an LED so I could see if the battery was good. He's got nice diagrams of the USB and regulator to help you wire this together.

Step 2: Disassemble the Battery:

Picture of Disassemble the Battery:

Pry the metal lip back from the bottom of the battery and straighten the edges as much as possible with pliers. Carefully pull out the plastic base and save. After that the innards should slip out without much trouble. Cut the negative lead going down the side and save the connector. Save the case.

I chose to use a Walgreens brand battery because it has nice thick plastic on the top and bottom. Duracell uses paper.

Step 3: Solder the Circuit Together:

Picture of Solder the Circuit Together:

For the USB I just drilled three holes in a row and cut out the rest of the rectangle with an Xacto knife. The USB should be mounted in the plastic before you solder the connections.

So the USB, LED, and resistor are on top and the regulator is on the bottom. The wire lengths are just to have enough room to epoxy the top in before the bottom, 2"-3".

Step 4: Prepare the 9v Case:

Picture of Prepare the 9v Case:

Sand the paint off the case with 400 grit sandpaper and rubbing alcohol. Carefully epoxy the LED and USB to the plastic base. Just use enough to tack it in place, don't get it in the USB.

Cut the case at about the 2/3 mark.

Score the inside of the case with a file or an awl to give the epoxy some kind of mechanical hold.

Step 5: Epoxy Putty the Top:

Picture of Epoxy Putty the Top:

Put just enough epoxy putty to cover the components on top. Don't put it all the way to the edge, you want it to fit in the case.

Once the epoxy putty has cured (not fully, just enough that it doesn't deform when you push on it), put the top half into the case and seat it against the lip. While holding it against the lip drip a small amount of liquid epoxy around the edge to hold it in place.

After the top is held in place fill the remainder of the case with putty, leaving just enough room for the bottom to be pushed in. Push the wires into the case and force the top into the putty 1/16"-1/8" past the edge of the case.

Step 6: Close the Case:

Picture of Close the Case:

While the epoxy starts to harden, cut 1/8" slots at each corner to help them fold over. When the epoxy has pretty much set up bend each edge over to close the case. Burnish or sand any sharp edges.

Step 7: Finished:

Picture of Finished:

Test with a multimeter before plugging in your USB powered device.


Schmidty16 (author)2016-05-14

what type of resistor is it

LightningJimmy (author)2015-08-10

Please change the title! This was an awesome tutorial but, it took me forever to find it because the title was confusing. Had it not been me searching on google images for it, I would not have found this.

holymoses (author)2015-07-21

Nice idea for the housing of it, but I always wonder how much capacity a simple 9v batterie shall have. I would rather put the transformer on a batterieholder containing AA or bigger primary cells.

PankajaGamage (author)2015-02-07

i have some problem in making the circuit how can i fix it..??? tried it twice with new parts but doesnt work..

Pranjal Joshi (author)2011-11-06

i think it wil damage cell phone coz cell phone need 4 volts and it supliies 9v??
can resistors decrease the voltage?
please rply someone

sweston (author)Pranjal Joshi2014-09-04

your right that's is why you use a +5V fixed voltage regulator (7805) between the battery and the female usb and led.

tutdude98 (author)Pranjal Joshi2011-12-03

5v regulator (Lm7805) drop voltage to 5v

Pranjal Joshi (author)tutdude982011-12-12

i made a project same to it..
but aftr charging my cellphone shows "bad contact of charger".. so wat can i do to repair dat??

tutdude98 (author)Pranjal Joshi2011-12-12

change the usb cabel or check the output voltage

Pranjal Joshi (author)tutdude982011-12-13

i chkd usb cable..
der is no fault..
n i nt yet got a multimeter to test output voltage.. :(
did u mean for 1st few mins. the voltage is more than 5v bt den it decreases below the minimum charging capacity of battery hence it shows bad charger contact????
if yes then wats the solution on it..

Roshy10 (author)Pranjal Joshi2012-07-02

you can get 2 100k ohm resistors and put one from positive to pin 2(data) and the other from pin 3 to positive(data) this will trick you phone which probably is realy trying to say "I'm not connected to a computer so I refuse to charge" (because it might be too many volts and over charge you phone.)

kumaran512 (author)Pranjal Joshi2012-05-23

7805 ic is used so u ll get only no harm to ur phone......

iApple guy (author)Pranjal Joshi2012-03-04

The regulator drops the voltage down to 5vdc, and actually phones and USB devices need 5vdc, not 4.

tolomelli made it! (author)2014-05-22

Thank you, the idea of use the battery case was great!

Works on Galaxy S, Moto G and Nexus 7.

(Sorry for my bad english)

freakyqwerty (author)2011-04-02

Is it me or does the title not tell what the instructible is...

Cheeseduck (author)freakyqwerty2013-04-24

Yet Another 9 Volt USB Charger

fogman103 (author)freakyqwerty2011-04-17

I think it satnds for Yet Another 9v USB Charger.

freakyqwerty (author)fogman1032011-04-24

I know-it says in the first step I just mean when your searching the site…

mm3814 (author)2011-07-10

it would work for an iphone right

Dalton63841 (author)mm38142011-07-18

It probably could, but I would not recommend it. That 7805 regulator is rated for 1 amp, and is going to get dangerously hot, even with a heatsink, burning off 4v of power to regulate 9v down to 5v. Not to mention that a linear regulator is TERRIBLY inefficient in this particular instance. A better option would be a switching regulator such as this one:

The switching regulator is still extremely small, and would easily fit if you left the casing only slightly longer. Also, switching regulators don't burn off the excess voltage, but instead use pulse. By turning the flow of current on and off VERY quickly, it simulates lower voltages. A linear reg gives you about 55% efficiency, whereas the switching reg gives you close to 90%, which means that battery will last longer also. Not to mention the added safety because that switching reg is rated up to 10 amps.

ledguy315 (author)Dalton638412012-10-03

You forgot to mention the addition of a needed 1k ohm resistor to the data pin on an iphone charge plug. Without it, it won't charge.

mhenriksen1 (author)Dalton638412012-07-22

If you wanna pull more than 1A from a 7805 you can just route the current around it with a PNP transistor and a resistor. Ofc it will still get hot if you pull alot of amps, but it might be a good idea nonetheless.

Damian James (author)Dalton638412012-02-29

USB is only supposed to be able to supply 500mA. I can understand going up to an amp, but 10A?

Dalton63841 (author)Damian James2012-02-29

The USB port on a computer only supplies 500nA. The cords can usually handle much more than that. Also, its, up to 10A, but it won't ever be that high. The circuit only pulls what it needs.

Actually i have made several of these for myself. The regulators I use are Radio shack 7805: +5vdc 1 amp. Even though these are rated up to 150 degrees celcius, mine stay cold to the touch after hours of use. They also incoporate internal overload protection as well as short circuit current limit. So these thing will fry themselves before they can damage your device.

faraz.h (author)2012-09-17


TigrisLi (author)2011-04-26

Can it charge a Iphone 4??

taylorglenn (author)TigrisLi2011-04-27

it won't charge iPhone 4. The iphone 4 requires 2.2vdc across the D+ pin of the USB connector and 2.8vdc across the D- pin. Otherwise, it will not charge.

TigrisLi (author)taylorglenn2011-04-27

Ok, thanks!

mrcolortvjr (author)TigrisLi2011-08-29

this is untested but i believe (from a bit of research) that if you use 2 2200 mA resistors it will charge the iPhone

Roshy10 (author)mrcolortvjr2012-07-02

I found 2X 100k works

neodymium (author)TigrisLi2011-10-17

This one will not charge the iphone4, but this one will: basically the same thing but in an altoids tin and outputs 2V across the data pins. this one will also work with any other usb charged device like the one in this instructable here.

charliedowler15 (author)2012-06-02

Wouldn't the battery that's sanded for the case get crushed easily?

kumaran512 (author)2012-04-19

nice cover idea...........gud job

nodoubtman (author)2012-03-08

i think that doesnt work for a ipod touch 4 G?

thank you!

mrcolortvjr (author)2012-02-22

I'm making this for an iPhone 4, so I'm using this regulator instead, because of a previously made comment. What grade of resistor do I use?

nanonano58 (author)2007-06-11

thanks dude nice one it also work whit psp & zune :P

wait....PSP can charge from usb?????

Yes it can, if you have the right cable. Most car chargers have this cable plugged into an adapter which plugs into the cigarette lighter.

oh ok cool. does the adapter go into the "USB" port on the PSP or does it adaqpt a ubs to fit the normal charger plug on it?

It looks like this:

jgosselin (author)hondagofast2011-11-07

making one would be easy. ground is pin 1 on the usb 4 is +5v on most cables its red for power black for ground.. and just make sure you wire you psp end plug to be middle positive outside ground.. job done.

jgosselin (author)jgosselin2011-11-07

bahh figures i try to remember something get it wrong.. pin 1 is +5volt power.. pin 4 is ground.. sorry for the mix up

yeah thats what I thought - ont an actual "USV" charger, it just converts USB to the normal chrager plug. but still cool. I should get/build one.

please excuse my typos :/

if you take a cable that plugs into your charging port on the psp, and strip all 4 wires, you will take the black, green, and white wires, and attach them to pin 4 on the usb, then the red to pin one, the data cables need to be grounded, i made one myself, and it charges off the pc

sanyo8088 (author)2011-11-01

can it charge a psp

tutdude98 (author)2011-10-09

ok can i use instead 9v battery , 4*1,2 V rechargeable batterys ? if i use will i need 5v regulator

BeefyHaze (author)2011-08-20

I admire the fact that you made something useful regarding usb's...

I just went through 50 pages of instructable usb ideas that all revolved around sticking a usb drive inside of some half-### enclosure.... Thank you for making a real usb instructable that serves a purpose.

courlander (author)2008-05-18

i have heard that some people are looking for circuit diagrams this might help a bit more green is Grnd Red is V+ and Blue is V+ (in)

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