This is submitted in the Make to Learn Youth Contest, and it requires me to add questions and answers.
Here are the questions:
1 - What did you make?
2 - How did you make it?
3 - Where did you make it?
4 - What did you learn?
Answer to all four questions:
I like using LEDs to light up things, but powering them isn't near as fun as making them. I usually end up having to use batteries, and it can be annoying to have to replace the batteries all the time. I eventually discovered that I could use a wall-wart to power LEDs, but the wall-warts were bulky and usually provided way more power than I needed. After further working with computers and electronics, I discovered USB power is usually rated at 5V and 500mA, perfect for powering a few LEDs. I made this LED logo lamp at home with some cheap stuff I had laying around. The logo is actually left over from a failed LED project, and it is the reason I ended up making this. I wanted to use it for something. Beyond the logo, the project was an experiment to see if USB power was easy enough to use for powering LEDs. It turns out that it is. From the research I did to make sure I didn't mess up my computer's USB ports, I discovered several things to be aware of before using USB for power. These are noted below in case someone skips over this part of the intro.
Here is how to make an LED logo light powered by USB.
NOTE! Be careful when plugging hand-made devices into a USB port on a computer, as a short may end up killing the computer. I recommend using a powered hub or a wall-to-USB phone charger; however, be careful as some chargers provide more than 5V.
Now, with that out of the way, let's get started!
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Step 1: Gather the Materials and Tools
In order to create a USB powered custom logo light, you will need:
- An LED (I suggest a bright "true" color LED, not one that has a colored cover)
- A resistor (more on it in a moment)
- A junk USB cable
- Something to cut your logo out of (like construction paper)
- Tissue paper / tracing paper
- Soldering Iron
- Wire cutter / wire stripper
The resistor value should follow this equation: R = (V1 - V2) / I
R is resistance in ohms, V1 is source voltage in volts (5V for USB), V2 is the LED forward voltage in volts, and I is the LED current in amps. More than likely, your LED will have a current draw of 0.02A (or 20mA), but the forward voltage can range from 1V to 3.5V. I ended up using a resistor with a value slightly less than the equation gave me in order to make the LED a little brighter, but beware, having too low of a resistor may fry your LED.
Step 2: Create the Box (or Triangular Prism, Whatever You Want to Call It)
1 - Cut out 3 squares of the cardboard that are about 1/2 inch bigger on all sides than you want your logo to be.
2 - In the center of one of the squares of cardboard, cut out a square that is 1/8 inch smaller on all sides than you want your logo to be.
3 - Attach the 3 squares of cardboard together in a triangle shape. I used duct tape to attach mine together, but it did not end up looking very nice; I recommend finding some other way of attaching the pieces together.
4 - After the pieces are together, trace the triangle the three pieces make onto the remaining cardboard, and cut the triangle out and attach it to the top.
5 - Paint the outside.
Step 3: Create the Logo
Note: image is of the back.
1 - Cut a square out of the material you want to use.
2 - Cut out the design from the square. Be sure to leave at least a 1/8 inch margin.
If your design is on the computer, I recommend printing the design at the size you want, attaching it to the material you are going to use for the logo and a piece of cardboard, and using a craft knife to cut out the design.
3 - Attach the tissue paper / tracing paper to the back of the logo.
My logo was actually left over from a different project. I made it by using a vinyl cutter to cut out my design from sticker vinyl and sticking it to tracing paper.
Step 4: Solder the Electrical Components Together
1 - Cut off the unused end of the USB cable and strip the end of the outer insulation.
2 - Trim off the 2 data wires (they will likely be green and white, don't cut off red or black) and any shielding.
3 - Strip the ends of the black and red wires. You may want to leave the black wire longer, so you don't have to use a jumper wire to cover the distance of the resistor.
4 - Solder one end of the resistor to the red wire and the other end to the longer leg of the LED. If you are going to use shrink-tubing to insulate the two wires from each other, remember to put it on BEFORE you finish soldering; it doesn't work very well if you don't... Trust me.
5 - Solder the shorter end of the LED to the black wire.
6 - Insulate the two wires from each other if you haven't already. Electrical tape works fine.
Step 5: Attach the Electrical Components to the Box
1 - Take a piece of printer paper and cut out a rectangle that is equal in height to the box, but wider, such that it bends and creates an arc when inserted into the box. The paper will reflect light and make it light up the logo more evenly.
2 - Cut a hole in the bottom of the paper big enough for the USB cable.
3 - Punch a hole in the box behind the paper big enough for the USB cable.
4 - Cut the USB cable several inches away from the LED.
5 - Feed the cut end of the LED's cable though the hole in the paper and the box from the inside going outside of the box.
6 - Gently bend the legs of the LED until the LED points backwards and slightly upwards.
7 - Glue the LED to the bottom center of the side with the hole for the logo so that the LED points up and away from the opening.
Refer to the pictures for more information on sub-steps 1 - 7.
8 - Re-attach the red and black wires of the LED's cable to the red and black wires of the USB cable, respectively. Don't forget to insulate them.
Step 6: Glue the Logo Onto the Front of the Box
1 - I hope you can figure out what to do from the title...
Step 7: Plug in and Enjoy!
1 - Plug in to powered USB hub or charger.
2 - Enjoy!
3 - If you are unable to complete sub-step 2 because it doesn't light up, try checking the solder joints and checking for shorts (I would say that if you find pants in your circuit, you messed up somewhere). If all of the connections are fine and there are no shorts, try flipping the connection of the LED to the USB cable such that the leg that was connected to red is now connected to black and vice-versa.
Comments are appreciated, and questions are welcome!