TheoAU wrote:Wayne - what resistors did you use with the HLMP-D101 LEDs?
I used the 2KΩ resistors Mike calls for in his schematic and BOM. I used that value for both my "red" and "blue" builds. They both have what I would consider to be the "proper intensity" and they look great.
As an aside, I find that LEDs illuminate pretty brightly with
very low current. Light perception must be like sound perception, on a logarithmic scale.
For example, I have a little
audio preamp controller that I developed for tube amp manufacturers. It controls RDACs to provide remote-controlled volume and balance. And it also includes an input switcher to control what source is active. The audio controller is based on an Atmel AT2313 (or AT4313), which monitors (front panel) push-button inputs and senses pulses from an IR receiver that reads the remote. It is also connected to the RDACs and to a bunch of LEDs that show power (on/off), input selected and volume.
I initially chose LED current-limiting resistors, the "normal" way, calculating the value based on voltage across the resistor and the desired current, basically 10mA or 20mA. Kinda standard. Works great for giving a nice safe resistor value that turns the LEDs on all the way without smoking them.
But man, the LEDs I chose for the prototype would put your eyes out. And they're not even the super bright LEDs that need heatsinks. They're just little-bitty things. But they'll still put your eye out.
So I started dialing back the current with higher and higher resistance levels. Ended up with a crazy high resistance of 12KΩ, and even that seems too bright.
All that to say the days of running a 220Ω or 330Ω series resistor to an LED with a 5v source are gone for me. They're
just too dang bright!