Many people are always wanting to know how to make a desk light powered from your computer. The answer is USB power with 5.0-5.5 volts available all the time it's the obvious choice.
The great thing about making a light using USB power is the ability to wire in LED's directly in pairs without a need for a resistor at all.
This project will demonstrate the most simple method of creating a group of LED's powered by USB.For this project you will need:
- LED's , I used daylight LED's which run on 2.2v to 3.1V with no issue.
- Soldering iron with solder (tin/lead will do)
- A mounting surface (Even an old DVD / CD can be used!)
I wanted a tray of lights to be mounted under a shelf as part of an effect, because of this the bulbs are quite evenly spaced out, for a brighter lamp just move them closer together. If your using an old DVD/CD then simply drill paired holes for the LED legs to go through.
I used L bracket length of aluminium shaped into a ] shape.
Using a hot-glue gun I fixed the pieces into place.
The LED's pair off with the longest leg as positive (notice the red tape). First I bent the positive leg too a rough bend, then did the same on another LED but on the negative leg. This provides a pair of LEDs that can be wired up and powered together.
To create the entire circuit I used 1 piece of electrical wire with slits cut into the insulation to provide a bare patch of wire, then soldered the legs into the patch, 1 in the positive line the other in the negative line.
You can however wire each group direct too the main power connection, because 2 LEDs uses all the available current within limits means you need no resistors in line at all.
The main connection for power simply requires chopping off the end on a old USB lead, inside you will find 4 cables (usually red, black, white and green). It's as simple as it looks with red as positive and black as negative.
You can see the effect from well spaced LEDs is a good glow but not in your face silly bright :)