Introduction: How to Build a USB Powered LED Light
The following instructable will walk you through the procedures to make your own USB powered LED light. You can use this light as a cool accent light behind your monitor/tv, even as a light to illuminate your keyboard or book in the dark. In fact this light will work in any USB socket. In order to safely construct this light you need to understand the fundamentals of electricity and electrical wiring. You will also need to be comfortable with soldering. This project should take around 30 minutes for an individual who is proficient at wiring and soldering.
Step 1: Gather Parts and Tools
The first step to constructing this LED light is to purchase and gather the necessary parts and tools. Hover your mouse over the parts in the pictures above to get a part number if you need help finding parts.
• 5mm LED light (3.6 volts, 25 mA)
• Resistor (68 ohms)
• 5mm LED holder
• USB 2.0 cable
• Electric Tape
• Wire Coat Hanger (Pipe cleaners will also work)
• Heat Shrink tube (optional, but preferred)
• Soldering Iron
• Rosin Core Solder
• Wire cutters
• Wire strippers (razor blade may be needed if wires are too small for strippers)
• Hairdryer or Heat gun
Warning: Do not have your USB cable inserted into any USB port while constructing your USB light (you might get shocked).
Warning: Place your soldering iron tip on its stand so it does not burn you or your workstation.
Step 2: Prepping the USB Cable
In this step you will cut your USB cable to a desired length referenced from the "A" (rectangular) end and identify the wires inside the cable (see picture 1).
a.) With your wire cutters, cut your cable to 12 inches in length, measured from the "A" end (see picture 2)
b.) Peel back the outer insulation around one or two inches to reveal the inner USB cable wires (see picture 3).
c.) Locate the red (positive) wire and the black (negative) wire; and use your wire strippers to strip about one inch off of each wire.
TIP: If your wire is too small to be stripped by your wire strippers, place the wire on a sturdy surface and make an incision down the wire with a razor blade (see picture 4 ).
NOTE: If your USB cable has other wires (green and white) securely wrap each end with electric tape. These wires are data cables, which will not be needed (see pictures 3 and 5).
Warning: Use care if using razor blades, they can cause serious lacerations.
Step 3: Attaching LED's and Resistors
In this step you will attach your resistor and LED light to the USB cable. The red (positive) wire will attach to the the LED light . The LED light will also be attached to the resistor, which will be attached to the black (ground) wire.
Tip: If you are using heat shrink tube slip it over your USB cable now. This will make it easier to set later.
a.) Insert your LED light into the LED holder (see picture 1).
b.) Take the stripped portion of the red (positive) wire and twist it around the long (positive) end of the LED light (see picture 1).
Note: A tightly bound twist is desirable because it ensures a good connection.
c.) Attach the short (negative) end of the LED light (see picture 1) to one end of the resistor using the same method in step 3b.
d.) Attach the other end of the resistor to the black (negative) wire, using the same method in step 3b.
Note: After completing step 3c your red wire, LED, resistor, and black wire should make a single loop, in other words they should be in series with one another.
Step 4: Soldering Connections
In order to make these connections secure, and permanent they will need to be soldered.
a.) Plug in your Soldering Iron and wait the manufacturer's specified time for it to heat up. While you wait use your wire cutters to cut a three or four inch section of solder from the soldering spool.
b.) Once the iron is heated touch the end of the iron to the LED-red wire connection for about 10 seconds. This heats up the wires so they accept the solder better (see picture 1)
c.) Immediately upon heating up the connection, take the solder and touch it to the heated twisted connection and touch the end of the soldering iron to the solder to help it melt. Once melted, remove solder and soldering iron and allow the connection to cool for a few seconds (see picture 2).
d.) When the solder has cooled, repeat step 5b and 5c for the LED-resistor connection and the resistor-black wire connection.
When completed your USB light should look like picture 3 above.
Step 5: Testing the Connections
Before you seal up your connections test them by inserting your USB light into a USB plugin. Performing this test before you wrap your connections in electric tape and heat shrink tube will minimize waste.
a.) Plug your USB cable into a USB port. Be sure to not touch a bare wire while performing this check, because you might get shocked! If the LED lights up your connections are good and you can proceed to step 5b (see picture 1). If the LED does not light up, unplug the USB cable and ensure the proper connections have been made (See step 3).
b.) When you have verified your connections are good, unplug the USB cable. Once the cable is unplugged wrap the bare wires with electric tape (see picture 2).
Warning: Do not touch or modify exposed components while performing your test due to electric shock risks.
Step 6: Add Structural Support and Seal Up
In order for the USB light to hold a desired shape a piece of wire coat hanger will be used. Once the coat hanger wire is inserted the heat shrink tube will be set in place using a hairdryer.
a.) Cut your wire coat hanger with your wire cutters so that the wire starts at the "A" end of the cable and ends right before the LED holder; this gives you the option of moving the tip of the light around (see picture 1).
b.) Once the wire is cut to length insert it into the heat shrink tubing, along with the USB cable (see picture 2).
c.) After inserting the wire, heat up the heat shrink tube with the hairdryer until it conforms to the shape of your wire and cable. If there are any parts (such as wire or cable) exposed, use electrical tape to seal them together (see picture 3).
Step 7: Congratulations!
Your product is now finished and ready to be used and enjoyed! With the completion of your new USB light you will now be able to add that extra ambiance to your monitor/tv or be able to see your keyboard in the dark.