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USB charge. Will this work? Answered

Will this work? please reply

with this LED work for me.....If i put the  USB cable from my phone or mp3 player  instead of the diode...Will this work?

P.S.  my english is not very well


No it will not work. First of all USB specifies 5V @ about 500mA max. 3V is not going to be enough to charge your phone or MP3 player. If your charging an iPod a diode or LED on the data lines of the USB cable will not be enough to enable charging.

I just finished a project where i added an iPod charging dock to a set of PC speakers. You may want to have a look at the schematics i created to build the charger.

Forgot i could post images here. Here is the circuit i used to create a charging dock for my iPod. The transistor is a 7805 Voltage Regulator to take the 9V coming in from my wall adapter and drop it to a steady 5V. The resistors are set up as voltage dividers so the data wires on the USB plug get 2V and 2.2V thuse telling the iPod it is safe to enable charging.

5V converter.bmp5V Charger.JPG

I was browsing the internet a bit and found something like this:



at your pictures I see that it comes to 9 DC...But I want to make 9 AC....and I found some videos and pictures with 9 VAC and 5 V regulator....what do you think about these videos....?


Just look at the videos. The 1st one will work form most items like i said but not newer iPods. The second video will work with an iPod since he is providing voltage to the data pins on the USB. Problem is the way he has it set up those pins are getting 5V. My understanding is this can cause some damage. That is way more voltage then what is needed to trigger charging. Personally i rather be on the safe side so i don't damage my devices.

If you want to charge off 9V AC you'll need a rectifier. All USB devices use 5V DC. For most USB items a basic 7805 Voltage regulator is all you need to take a 7V DC to 35V DC (if you use more then 9V you'll want a heat sync on the voltage regulator) power source to charge them. But if your planning to charge an iPod you will need to put about 2V DC on the data lines to trick the iPod into thinking its OK to enable charging. Just check the voltage output of the regulator before you plug anything in. If the voltage jumps around you may need to add a couple of capacitors to smoothing it out like i have in my schematic. But if you have a good regulated source going in you'll be fine.