Showing 1 of 2440 conversations about:
View Full Discussion
What size and color LEDs will work under the keys? Does the driver chip support a range of different types or only one? I've already joined but am looking at LEDs now. Planning ahead :)
Which LEDs do you normally get, and what resistors are you putting on them? Most of those guys use a lot of current, have you tried something in the 20ma or below range?
Looking at the LED driver datasheet I think we will be able to use any color LED we like (please correct me if I'm wrong). The driver chip uses 1 external resistor to set the current for all the LEDs in the grid (it supports up to 144 total). If the PCB uses a 20kOhm resistor like the data sheet suggests then the average current that will be supplied to each LED is 3.2mA. Looks like the brightness of each LED can be changed using the driver in 255 step increments via pulse width modulation (PWM).
The mA ratings shown at http://shop.evilmadscientist.com/productsmenu/partsmenu/388 are maximums each LED can handle. They will still light at lower currents.
Yes, we are planning on using a 20kOhm resistor unless I find that I'm burning out leds. Unlikely, the brightness level can just be lowered.
In the case the leds are too dim, the external resistor can be replaced (even though small, still a single resistor).
Ok, makes sense. Do you know what kind of driver chip is being used?
I've got some nice bright whites I'd love to use, but they're already ~6000mcd@20mA so I've definitely going to have to cut the current way back. Love to get all my ducks in a row before the kit arrives.