It it a nice touch around your PC or anywhere in your room. It won't be able to light your room fully, though you may use such a bulb to see the keyboard keys in darkness or just add it to the interiour.
The process is relatively easy and there are no special components that you need.
Step 1: Components & Tools
- Green LED
- 330 Ohm resistor
- USB Cable
- Soldering iron
- Soldering wire
- Desoldering Pump
- Hot glue
- Cable nippers and pliers
- * You may need a breadbord to do the prototype and test the if the resistor you use is right but you can skip this step
Step 2: The Bulb
NOTE! This step includes working with glass, which is dangerous and you can injure yourself. Take care and be patient when going over the process.
Start by applying some soldering wire to the soldering iron. This will make the desoldering much easier.
- Heat the solder dot at the end of the bulb.
- If it doesn't melt add more soldering wire.
- Tap the bulb downwards and the melted solder will fall. You can use the pump as well to clean the solder.
- Do not try to remove the solder 100%, just get to the point where you see a hole with a metal wire in the centre.
- Using a thin screwdriver for example break the wire link as you do not want it to link the metal part to the bulb anymore.
Step 3: Detach the Metal Part From the Glass
First of all grab a piece of fabric and sprinkle some water on it. Then grab the glass part of bulb with the fabric in your palm. This will protect your hand if the glass breaks.
Now grab the metal part of the bulb close to the glass with the pliers and apply little pressure on the pliers. You do not want to smash the glass! Continue working on the metal twisting the bulb a little bit and applying pressure again. You want to go over the whole edge so rotate the bulb a bit after each squeezing.
The metal part will eventually fall off, but if you struggle a lot try heat the edge with the soldering iron. The heat will make the edge expand and crack the glue underneath.
Picture 4 shows what should not happen. I applied too much force with the pliers and it all went wrong.
If you are lucky the metal part will detach as you can see on the next pictures.
Step 4: Fit the USB Cable
Get the cable you want to use and cut whatever is hanging on the non-USB end. Fit it through the hole and tight a knot, then make sure the knot goes into the metal part deep enough.
Step 5: Get Ready to Connect!
There are the LED and the resistor that have to be hidden. You can see how i soldered them to each other fitting them close to each enough so they don't take a lot of space.
Next comes the cable. The USB2.0 standart cables have four wires in them - Red, Black, White and Green. Red and Black are the 5V power lines and the other two are the data lines. The data lines can be shortened at different lenghts, then isolated with a piece of shrink tube and then you can put them in the knot facing backwards. This wil make more spae for the LED connections.
Fit the knot in the metal part. Your project should look like on the 5th pic.
Step 6: Connect!
- Measure the current flowing through the LED and the resistor. It depends on the LED, but in most cases this current should NOT exceed 15mA. How to measure it? Connect one leg of the LED to 0V, the other leg is connected to the resistor. The free resistor leg goes to one of your multimeter's plugs (does not matter the color) and the second plug is connected to +5 V. So the current flows like in a pipe constructed of the LED, the resistor and the multimeter.
- Now switch your multimeter to the mA (DC) measuring function and check whether you have to move the cable plugs or not (depends on the multimeter you use). After connecting the power, the LED should start emitting light and you will see how many miliamps flow though the circuit.
- If nothing happens reverse the LED's legs as it does matter. You can reed more here.
- In my case the current was 6.29mA which is normal.
At this point I tested the LED plugged into the USB and it works! Beautiful!
Step 7: Fit, Glue & Enjoy
Now apply hot glue around the connections and to the edge where the glass was originally held. Try to apply a thin layer of glue and then press firmly.
Lastly, the point where the cable goes out of the bulb should be gued. Apply some hot glue while turning the bulb around at constand speed.
You are ready! Now sit back and enjoy!
+ You can even plug the LED bulb into most mobile device chargers that have a USB connector.