Flat Plug

Why are car accessory plugs so bulky?
Why are they barrel-shaped?
If you travel for a living and bring gadgets you also need to bring along all the charger and adaptors.
Having a USB car accessory plug adapter/battery charger isn't a necessity but is a life saver in an emergency.
To pare down the bulk of all your gadgets and accessories, wouldn't it be great if the car charger was smaller?
In this Instructable we show you how to make a flat USB charger for the car or airplane.

This Instructable is very easy.
We use just two components.
The venerable LM7805 5V regulator and a USB connector.
The 7805 takes 12 volts and converts it to 5 volts.
5 volts is what's needed for USB power.
The body is made from sheet ABS plastic and has an unusual shape.
The shape was designed to utilize the plastic's elasticity.
This eliminates the need for spring mechanisms as found in most car accessory plugs.
Keeping it simple!

Tools:
Dremel tool
Drill
Hot Glue Gun
File
Sandpaper
Scissor
Centerpunch
Soldering Iron

Parts:
ABS Plastic Sheet 3/32 inch thick
Brass tube 5/32 inch diameter
Brass channel 3/16 x 1/8 inch
LM7085 5V Voltage Regulator - Radio Shack 276-1770
USB Type A Jack Female - Digikey 151-1082-ND
Recycled White Plastic Bottle
Misc Wire
Contact Cement
Clear Self Adhesive Labels
Silicone Sealant
Crazy Glue

Step 1: Make the Body

Print out the template in the attached "TemplateandWiring.pdf."
Cut it out and cement it to the sheet plastic.
Rough cut the template from the larger sheet plastic.
Center punch and drill relief holes.
The body is too small to hold while using a Dremel so mount it to a piece of scrap wood first.
Screw down the cut-out to the wood.
Using a Dremel tool cut the template to shape.
Finish it off with a file then sandpaper.
Remove the paper template.

Note: Some of the photos show "feet" included in the shape.
These feet were supposed to be a grip to pull out the plug.
It was found these feet were not needed in the final design.

Step 2: Make the Brass Contacts

Car accessory jacks, the female part, have electrical contacts at the end (positive) and around the circumference (negative).
The flat plug needs to touch these contacts with conductive metal.
The electrical contacts for the flat plug are made from brass stock.
Cut the brass tube to length, about 3/8 inch long.
Make two of them.
Then cut about 3/16 inch length from the brass channel stock.
Shape to size with a file and sandpaper.
Hot glue the contacts to the body.

Step 3: Add the Components

Crazy glue the 7805 regulator to the body.
Glue the USB jack to the body.
Be careful on the position of the jack.
It is easy to get confused about the negative and positive terminals.
Refer to a pin out guide.
Such as: http://www.allpinouts.org/index.php/USB_-_Universal_Serial_Bus
4 Pin Female "A" Connector on the computer.
Per the attached schematic wire up the components.
The positive line goes to the tip and then to the "In" pin of the 7805 regulator.
Then negative contacts on the side are wired together then soldered to the "Gnd" pin of the 7805.
Then wire up the "Out" of the 7805 to the positive of the USB Jack.
Finally, wire up the "Gnd" of the 7805 to the negative of the USB Jack.
Test it by plugging in your USB cable and device.
Insulate the exposed contacts with silicone seal.
Hot glue the wires to the body to prevent movement.

Step 4: Make the Character (Optional)

This step is optional but adds some humor to the project.
A jet pack man character was created since the outline looks similar to a jet pack.
Of course, another character can be created.
Print out the character on a clear self adhesive label.
To protect this image, add another clear layer on top.
Find a recycled plastic white bottle.
With scissors cut out a piece large enough for the character.
Stick the character onto the plastic and trim.
Hot glue the character onto the flat plug body.

Congratulations! You are done!
Now enjoy carrying less junk around! : )