Today I ordered a 2x16 character LCD with white characters on black background.

Now I am wondering if I can change the backlight LED, which I guess is white for the characters, with a RGB LED to change the character color.

Did anyone do this before? Is it even possible that way?

I've seen RGB negative LCDs from Adafruit and Sparkfun.

  • Not all LCDs are the same so you'll have to look at the item's datasheet for this. Do you know the part number? – Peter Bloomfield Nov 20 '14 at 13:44
  • Thanks for your answer! Ive got this one: mikroshop.ch/LED_LCD.html?gruppe=7&artikel=467 Theres a link to the datasheet. Stan – Stantastic Nov 20 '14 at 13:48
  • @IgnacioVazquez-Abrams Thanks Ive already seen these as i said but i was wondering if i could replicate the same effect with a white/black lcd and some rgb leds on my own – Stantastic Nov 20 '14 at 14:58
  • Adafruit also sells the waveguides alone, so you could take an existing backlit LCD, strip out all the backlight hardware, put in a new waveguide, and glue on a new LED. – Ignacio Vazquez-Abrams Nov 20 '14 at 15:43

The backlight led (sample) is just a simple led with a large transparent panel, the size of the lcd, attached to it. This panel is diffused on the top in such a way that it distributes the light evenly. If you get a rgb led, file the top flat, and glue it to the side of this panel (where the leads get out of the plastic) you should get a pretty good effect.

I tested it on my white-on-blue lcd, by holding and led to the side of this panel, and it worked. Just note that you need a very bright led. Mine was pretty bright but the letters didn't light up that much.

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The product you linked looks like a fairly standard LCD module, so it's probably very difficult to swap the backlight LED. Like most electronics, they're not designed to be modified by hand. It would likely need some precision re-soldering.

When you see LCDs with other types/colours of backlight, it's usually because they were originally manufactured that way.

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  • I also have a 4x16 character lcd with white on blue thats why i thought of just ripping out the white led/smd, glue in the rgb led and control it via 3 potentiometers. – Stantastic Nov 20 '14 at 14:53
  • I'd be careful if you want to try that. You could easily damage the LCD in the process. – Peter Bloomfield Nov 20 '14 at 15:09
  • Over all this theoretical diskussion is it even correct that the led is coloring the characters? So the white makes white chars and blue for example makes blue chars? – Stantastic Nov 20 '14 at 15:12
  • Yes, for a negative LCD that's how it usually works. The LCD blanks out most of the screen, making individual pixels transparent so that the backlight shows through. – Peter Bloomfield Nov 20 '14 at 15:50

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