Make a Simple USB Light




Introduction: Make a Simple USB Light

I've recently acquired a "high end" soldering station so I find myself enjoying soldering lately. That being said, soldering always needs good lighting. I almost always have my computer next to me when I'm working on something so I decided to make a simple little USB light that was easy to manipulate and put where it needs to be.

Step 1: Parts Needed

The parts list is simple and I had the materials lying around. You can probably get this from a Radio Shack for a few dollars or scavenge something broken.

-62ish OHM resistor***
-LED of your choice
-Old USB plug
-Twisted wire or hookup cable
-Relatively stiff wire (doesn't have to conduct electricity)
-Sugru (optional)
-Some tape (electrical is probably the best)

***Resistor may vary depending on your LED needs. Source voltage is about 5 volts from USB. I suggest this website if you don't want to second guess yourself: I use it all the time because I doubt my math abilities.

-Wire snips
-Soldering tools
-Scissors/hobby knife

Step 2: Cutting

First you will want to decide how long you want the light to be. I guesstimated and cut mine about 15 inches. You will want to cut two of these for positive and negative. Second you will want to cut up your USB plug as it show in the picture.

Pro Tip: Don't use a USB plug with shielding like I had. It makes it far more annoying to cut up with shielding.

After you hack up the USB plug, find the positive and negative wires. Don't assume that red is positive and black is negative. Never assume in electronics. In my case, yes red was + and black was - :). But I checked and that's what counts. Cut the other wires if any, you just need power.

Step 3: Soldering the LED

Strip your main wires and solder them closely to the LED on the LED pins. Remember which pins are positive and negative. If you forget, you can look inside the diode and tell. The to pins connect to a large metal piece and a small metal piece in the diode. The larger of the two inner metal pieces is the negative side, the smaller is positive. Found this out by forgetting which one was which after I cut them.

Step 4: Soldering the USB Plug

Once you have the positive and negative wires separated out on the USB plug, it's time to start soldering. Solder the resistor to one of the wires. You want to solder it as close to the base as possible just to keep everything compact. Once the resistor is soldered on, solder the LED wires to the USB plugs wires and remember to get the polarity right.

After it's all soldered up, plug it in and make sure it works. This is important in case something was messed up. You don't want to finish the project just to find out a wire was wrong or a solder joint was bad. After you confirm it's working, seal the joints with tape or some liquid tape. Cram the wires on the USB side back in to the sheath as much as you can and then tape it back up.

Step 5: Giving the Wires Support

This gives the LED light the twisting and holding capability it needs to be useful. I had some jewelry wire laying around so I used that. I took it and measured out a length three times longer that the wires and ran it back and forth. Once you have the support wire measure out, tape it to the length of the wire for the LED.

Step 6: Make It Pretty

This of course is optional but recommended so nothing shorts out or breaks. This was my first time using Sugru and I do plan on using it more. I simply took a small bit and sealed the LED head with it and then took the rest and wrapped it around the base where the wire connects to the USB plug.

Step 7: Other Thoughts

This can be done many ways and has many options. Below are a few things I may try if I ever do a version 2. I found out too this is a pretty good laptop light for typing at night. However, it's a little long for that so if you want it for just a computer light, I would suggest just a few inches.

-Use a potentiometer (like a 0-200 ohm pot in series with a 62ish ohm resistor) for variable light.
-An on off switch
-Use magnet wire so you don't have to have the conducting wire and support wire separate.
-Have the LED swappable so you can change colors.



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    15 Discussions

    I like this project and being that my keyboard does not light up this will be perfect for me. Any thoughts about a cover to or shield to reduce glare ?

    Nice project.

    It's screaming to be done with shrinky tube instead of tape.

    So I saw the part where it said "make the LED swappable" and so I said, Challenge accepted. All you need is an old strand of lights! clip one socket off and then stick some led's in the bulb housings and voila! Interchangeable lights! Thanks for the instructable!

    A resistor is needed for an LED for a USB supply. Some LED's come with the resistor built in. You would need to look at the LED specifications. With no resistor, most LED's would burn out almost instantly.

    Just use Ohms law to figure out the resistor value. Find the voltage drop of your LED (it's on the spec sheet), usually 1.7 - 2.4v. Ohms law says I = V/R. You want about 20ma of current through the LED (more and you will shorten the life - a lot more and you will shorten it considerably and let out the magic smoke). So, given that .02 = V / R and we know that V will be supply minus the voltage drop across the LED, or V = Vcc - Vled. Let's use 2.0v as an example, so 5.0v - 2.0v = 3.0v dropped across the resistor. So now we know V, let's solve for R. R = V / .02 or 3.0 / .02, or 150 ohms. The next highest value that is standard is probably 220 ohms so go with that. Anything less and your LED will not last as long and/or you could fry it.

    3 replies

    I know the math. I just don't like dividing decimals, digging for a calculator and making mistakes. I'd rather use a program. I have a program I wrote on my calculator but I have to find the calculator :). My laptop is always there and I've never lost it. Works for me.

    I made sure to point out different diode ratings. I've blown a few in the past assuming they needed the same power.

    I personally don't like those calculators. They tend to abstract what calculation is going on. Ohms law, KCR and KVR are all derived from Maxwell's equations. There is a reason why they work and understanding those ratios, at least at a higher level than Maxwell's stuff, is important when building circuits. Just my two cents. When I teach BEE I always stress learning Ohms law over using some calculator app. Will that app tell you how to bias a transistor for class A operation? Of course not, but Ohms law will! :)

    I agree. Knowing the math is important and will help you in the long run especially in troubleshooting, but I'm lazy lol. I just go with what's easiest and quickest most of the time for simple things like this. I'll admit I'm more of practical electronics than the theory behind it, and I regret it most of the time by burning up things. If it's something complex I'll sit down and work it out, but for LED's, I just use a calculator. I know the rough range it should be in so it's not like I'll trust it if it throws some crazy result at me (I have seen a few do that).

    Here's an idea! How hard would it be to replace the earbuds on a pair of headphones with LEDs so that the electricity going through the audio jack would make them flash along with any music you're playing? Would the audio cable not supply enough power? Of course, you would have to have a headphone splitter if you actually wanted to listen to the music at the same time.... It's a highly impractical project, but it might be fun for experimentation.

    1 reply

    Sharpshot, you could hook something like this up but in all likelihood it wouldn't be nearly that simple. To begin with, an analog audio signal like the kind coming out of an audio jack is AC, whereas an LED (by definition of being a diode) only allows current flow in one direction, and so would really only work (or would work most practically) with DC, so you'd need some rectification circuitry to accommodate that so it would accurately reproduce the sound as flickering light. Additionally, the voltage level of that signal is in all likelihood very small, in the millivolts (mV) range, whereas supply voltage and current for an LED would need to be much higher than the signal would provide, so you'd need some amplifier circuitry to step the signal up to the required level.

    So yes, it would be possible, just not as simple as your initial thought. If you're interested in finding out more about it you can always play around with it yourself, or check out the link at the bottom, its a similar concept to what you're thinking.

    I got mine directly from their site. Other places sell it but from what I googled, it was cheapest directly from them. I ordered 12/3 and got it 12/8.

    you can also make your own. There are several Instructables that tell how to do it.