If you need a low-power LED light near your computer, but there is no extra outlet in the extension cord, don't despair. You can also power the LEDs directly from your computer. This can be done in two ways.
Instructions
Step 1
The first way to get power for LEDs is only suitable for desktop computers. To use it, remove the Molex connector from the damaged CD or hard drive. By connecting it to a free connector of a power supply unit of the corresponding standard, you can remove two different voltages: 5 and 12 V. Voltage +5 V is present on the red wire, +12 V on the yellow one. Both black wires are common and are connected together inside the power supply.
Step 2
The second method is suitable for both desktop and laptop computers. Take any out of order device designed to work with the USB interface. Remove the cord from it. +5 V will be present on the red wire, and the black one is common. The cable sheath, if any, is also connected to ground. Insulate the remaining wires and do not use.
Step 3
If the supply voltage is 5 V, connect in series, observing the polarity, two red, yellow or green LEDs, or one blue or white. Use a damping resistor with a resistance of 200 ohms and a power of 0.5 W. If the voltage is 12 V, connect four red, yellow or green diodes in series, or three blue or white diodes. Use a damping resistor of the same power, but with a resistance of 500 ohms.
Step 4
Strings of LEDs and resistors connected in series can, in turn, be connected in parallel. Measure the current consumed by one chain, and set their number so that the total consumed current does not exceed 0.5 A. This is especially important when powered from the USB interface.
Step 5
Disconnect the illuminator from the computer before performing any re-soldering. Assemble it in such a way as to completely eliminate the possibility of a short circuit. Be sure to use the enclosure. Direct the finished illuminator at the keyboard, excluding the parasitic illumination of the monitor.
