YAN9VUSBC

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

5v regulator (Lm7805) drop voltage to 5v

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??

change the usb cabel or check the output voltage

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..

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.)

7805 ic is used so u ll get only 5v......so no harm to ur phone......

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

Yet Another 9 Volt USB Charger

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

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

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:
http://focus.ti.com/lit/ds/symlink/ptr08100w.pdf

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.

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.

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.

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

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.

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.

Ok, thanks!

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

I found 2X 100k works

This one will not charge the iphone4, but this one will: http://www.instructables.com/id/Make-a-USB-iPhone-iPod-Charger-On-The-Cheep/ 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.

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: