USB Car Charger





Introduction: USB Car Charger

This is a Home Made Usb charger with this device  you can charge in your car any Usb charged device like mobile phones, bluetooth headsets, Gps , cameras, mp3 players, etc..
This device I made haves 0.5Amp output that is the normal power output on a computer, if you use a bigger transistor you can  get more output amps.

Step 1: Parts & Tools Needed

This are the parts needed to assemble this home made USB charger:

-cigarette lighter plug
-Usb female Port  (taken from a old computer Motherboard)
-5V regulator, 78M05 or 7805   (taken from broken playstation, you can take from other broken device or buy)
-resistor 100 Ohm or 220 Ohm
-Heat Shrink Tubing

-Solder Iron
-Solder lead
-Solder Paste
-Hot Glue Gun

Step 2: Schematic

This is the schematic

The standard 7805 was to big to fit inside my cigarrete lighter plug.
So i used the 78M05 a SMD transistor because is smaller then standart 7805, and haves 0.5A that is enough for the USB charging.

Step 3: Cigarrete Lighter Plug Drill

I made this holes with the Dremel to fit the the USB female .

Step 4: Soldering Parts

In this pics I show the transistor and wire setup

Step 5: Soldering Led's

This Pics show final circuit with the Led already mounted
I Used the Heat shrink tubing  to isolate some soldering points

Step 6: Fit the Circuit Inside Plug

I this part I used the Hot Glue Gun to glue the Usb Female on the back of the cigarrete lighter plug.                                                                                           

Step 7: Finished Product



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    For those who are asking about high heat dissipation or unable to charge
    device. LM7805 does not magically converts 12v to 5v. It will
    dissipate the 7v as heat. It rapidly changes it's resistance in while
    maintaining a fixed ratio of res(7805) : res(load) to Volt(IN)-5v : 5v.
    For example if input is 12v and load resistance is 5ohm (i.e. 1A load
    current @ 5v), the ratio of resistance will be (12-5) : 5 -> 7 : 5,
    thus 7805 will have a resistance of 7ohm when input is 12v and load
    current is 1A. At 41.6% efficiency a 5W load will appear 12W load to the
    battery. However it is more preferred than efficient SMPS when the
    output voltage has to be extremely stable or when energy consumption is
    low or when energy is cheaper than the IC itself. For those who wish to make a very simple, cheap & efficient SMPS i would suggest them AD84064 ic or more common 34063 ic (w/ 2 more resistors to add than AD84064).

    Hi I am try this circuit using 12v 1amp DC adaptor. But 7805 voltage regulator produce large amount of heat.
    How can solve this problem.

    Mine doesn't work, I'm running it off of a dirt bike for a camping trip useing a L7805CV and it won't charge. I'm only useing the led and the usbs in the picture, not the button. know I have the pins right. And both lights work.


    i couldn't really get it to work....bcoz i have it connected to a solar panel with a 15 volt output...n when i connect it to a phone, it doesn't charge....basically, when there is a load, the voltage drops. plz help

    Hi there, I did this same thing and mine didn't work because the solar panel doesn't create enough current to charge my phone...the best bet is to plug it into a 12v power source from a battery or indoor socket adapter and check to see if ti is working; if it does you know why the solar panel will not work.:-) I know it has been a year but hope this helps.

    what about DC chokes and stuff? i dont want my alternator to be feeding into my devices usb. also i would reccomend a computer heatsink, these regulators can put out bonkers heat.

    Does your charger get REALLY hot? I made one like this and it gets so so hot. It has to dissipate so much engery to take the 12v to 5v... How do you solve this?

    Shouldn't the data pins of the USB be shorted together, to indicate it's a dedicated charger?

    I've found an easier solution. Browse any discount store for car cell phone adapters. Some cell phone batteries charge at 5.1V and 550mA. Perfect for a straight across USB splice! And don`t forget the sugru.

    No one here really has thought this through properly. The 7805 should be heat sinked. Its not so much because of the current the 7805 is supplying to the usb connector or external device being powered that I am concerned with. Its the fact that the device takes the 12 volts or more from the car power and drops it to 5 volts. That is a drop of 12-5=7 volts. The 90 or 95% efficiency has to do with how the 7805 handles the droping of the voltage. If the device you are powering is 200ma, and the 7805 is 90% effient, that means you need to draw 200ma x 1.1 to get that current out, or 220ma into the device. Now take the drop of 7 volts x the 220ma=1.54 watts of heat produced by the 7805 in dropping the voltage. (Volts x Amps =WattsPwr) Now 1.54 Watts does't sound like much, but that will get the 7805 pretty darn hot. If you check the 7805 data sheet and do the calculations, I think you will see that a heat sink is needed. especially for the lower power version.