Quote Originally Posted by lerameur View Post
i have a potenetiometer between the 5 v and the LCD, I swiched to the 12v with the pot, and the LCD is finished
Sorry to hear that you toasted the LCD but I didnt suggest running the LCD from the 12v supply.... just the backlight.

If you had read the other threads about this you would see the reason behind it. The LCD only takes a couple of milliamps but the backlight takes 50-80mA which is a lot of extra for the regulator to handle.

The backlight doesnt need a regulated supply, just a current limited one hence the use of a series resistor which you calculate according to the forward voltage of the backlight , the required current through the backlight and the maximum voltage of the unregulated supply.