Portable USB Smartphone Charger V3




Hi Instructables audience!

In this instructable i'm showing you how to make simple usb charger.

This is my 3'd version for this kind of charger and this one is upgraded to allow voltage to flow on stable 12v and no backward flow.

Basicly this one works on it's full potentional ,without any possible way to dry you phone/electronic batterie because of diodes and voltage regulator.

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Step 1: Gathering All Parts.

For this project i'm using standart 12v usb car charger ,LM7812 voltage regulator , two diodes and 9v batterie clips.

Step 2: Hacking Housing and Soldering Parts Together.

You'r going to need to fully disassemble charger and remove metal connector from + terminal and metal bracket form USB which is used as ground.

Then trim transistor leads to acceptable size and saw off excess metal witch is used as heat sink ,batteries dosent pronounce as much voltage to heat it so much, and as we assemble the build ,USB metal shielding will act as our heatsink instead.

Solder diodes to right polarities and then solder 9v batterie cilps in series to provide 18 volt input and then solder it to voltage regulator witch will drop voltage to 12v , diodes you added earlier wont let voltage to go backwards from phone to charger.

After you have done all this you'r ready to use your charger! Just glue all in place and close charger case.

Step 3: Video

And here is little video with all steps and extra pictures.

Test in the end of video.

Thanks for reading! ;) Cheers!

1 Person Made This Project!


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9 Discussions


5 years ago

Hey that's a great idea and all but why don't you give it a houseing so you don't have 2 Batteries sticking out. 1 the way you have it you can loose a batterie.2 make it look a little more professional. But all in all I love it


5 years ago

Nice gadget - I like it. On the vid at 1:18 there's a hair. I hope you have a beard otherwise it might be a pube! X-)

1 reply

5 years ago

Still don't get why people try to be smart using low capacity 9v batteries..
While actually you're wasting a lot of power.
You go from the 2x9v=18v to 12v, converting 6v to heat!, and then the car adapter turns it even further down to 5v, again losing power.

Try using 4AA batteries and an LM7805 which is much more efficient.

3 replies

Reply 5 years ago

or 2x18650 and 5v regulator to step down voltage


5 years ago

why not just one 9v battery wired into the system? there is already a diode to prevent back feeding power into the power source and it must have some small regulator built in to step down the 12v auxiliary of a car into 5v output.