Please help me select LEDs

[Art of Payce]

Dear GH,

I want to install these red LEDs, these blue LEDs, and these white LEDs on this board which has fairly dim stock orange LEDs. I don't mind the brightness; I just want to change the color.

I need the brightness to be about even between red and blue. I prefer white to be somewhat dimmer but it's not a big deal. I'm looking at the listed MCD for luminosity, but I have no idea how the other specs should factor into my selection. Would anyone happen to have a minute to check this out, point me to a thread or reference, or explain to me what I should look for?

Grazie,
AoP

[Thechemist]

Dear GH,

I want to install these red LEDs, these blue LEDs, and these white LEDs on this board which has fairly dim stock orange LEDs. I don't mind the brightness; I just want to change the color.

I need the brightness to be about even between red and blue. I prefer white to be somewhat dimmer but it's not a big deal. I'm looking at the listed MCD for luminosity, but I have no idea how the other specs should factor into my selection. Would anyone happen to have a minute to check this out, point me to a thread or reference, or explain to me what I should look for?

Grazie,
AoP

I haven't worked on this keyboard or know that much about it but I can tell you that orange leds are 1.8 - 2.2fv so anything on that keyboard will be dim besides the red leds which also have about the same forward voltage.

to have the red, white , blue leds on a keyboard start with a keyboard that comes with the higher voltage leds ( like white, blue, purple ) and then swap leds. I would suggest either 1.8mm leds, 2x3x4 leds or 3mm round flangless leds. All of those will work great in a cherry switch.

[Art of Payce]

Thanks for the reply, Thechemist.

I'm afraid I have to work with this board because there isn't really a better TKL option with LEDs on the bottom. After further research, I've found that LED specs vary quite a bit from color to color and in particular, the rate at which luminosity fades over time. I think I may have to postpone this mod. Orange should still be one of the most visible colors under dim conditions so maybe going stock is right for me...

[Oobly]

If you do still want to do the three colours, you can choose LED's with somewhat similar brightness, but they don't have to be too close. They will have different forward voltages, so will need different resistor values anyway. You need a PCB that has a single resistor per LED, not ones that have one per group. Most of the better boards are like this, but there are one or two thst group the LED's.

Then you choose the one with largest forward voltage (probably white) and set up a couple using a variable resistors (trim pots) to adjust the brightness to a good level using the contacts in the PCB to supply the power. You could even install them in the board and hook up the trim pots to the resistor contacts. Then set up a couple of each of the other colours and adjust them so they appear to be the same brightness. Use a multimeter to read the trim pot resistance and choose the closest standard value resistance. Then you know what resistor value to install for each colour.

If there isn't a standard value close enough, you can often use 2 in parallel or series to make up the correct value, but it requires a bit of fiddly soldering to mount them.