Keyboard backlight turns on when you press the Fn key and one of additional keys. What is key to include - depends on the model of laptop.
In many cases a shortcut can be defined visually, as added keys (used by a number of F1–F12) manufacturers apply additional characters. The color of these symbols is the same as the inscription on the key Fn. Experiment by pressing together with the Fn keys with additional symbols. Look for the figure with the symbol illuminated keyboard.
Note that when you press a key you can use other options – screen off, entering sleep mode, etc. to cancel changes, press the same combination again.
If the drawings on the keys does not reveal the right combination, you know that the backlit keyboard on your laptop have, try the following combinations:
- Fn + F6 or Fn + right arrow;
- Fn + SPACE (space);
- Fn + F5.
In that case, if your laptop keyboard has no backlight, it is possible to make the external lighting using the +5 V power supply from the USB connector, and one or more white LEDs. In the connector you need two outer contacts (left and right). The supply voltage of white led is equal to 3.5 V. So the resistor that will be extinguished excess of 1.5 V. the led Current of 20mA, or 0.02 A. Then the resistance of the additional resistor will be 1.5 V/0,02 = 75 Ohms.
If the brightness of a single led is not enough, connect one in parallel with the same resistor. Always check consumed by the led current, since it differs from 18-20 mA negatively affects the service life of the led. Need current set resistor selection. The USB connector can give up to 0.5 And means that it can be powered up to 25 LEDs.