I've built my own Android version of the IR remote for Roku devices, but with a bit different functionality. It's working, but the IR seems a bit more flaky than a real Roku remote, and the Roku remote is brighter on my phone's camera.
I borrowed the LED from an old universal remote, so I want to assume it's 940nM but don't know for sure. My Arduino is currently powered by a regulated 3.3V, A GPIO pin drives an NPN transistor, which in turn provides collector current from the 3.3V supply through a 33R resistor to the LED, with the emitter at ground. The base resistor is 2.2K. The voltage drop of the LED is 1.2V, and it's kinda blue. The Roku remote is powered by two AAAs.
So I'm getting more than 60ma through my remote's LED, which if the relative brightness thing is meaningful, makes me wonder how much more current the Roku remote LED could be getting. But specifically I have these questions:
1. Is there any reason to believe that the Roku IR system uses anything other than 940nM or anything other than 38K? Rokus seem to work fine with universal learning remotes, which I would think all use 940nM LEDs.
2. Is there any reasonable way to determine whether an LED is 940nM or 850nM?
3. Do IR LEDs come in high-efficiency super-bright versions like red LEDs do? What spec would tell you that an IR LED is one of those? Does anybody have a favorite that's very "bright" on very few milliamps?
In case it matters, and it might, the Arduino is 3.3V, 8MHz, and the IRremote library is driving the LED, I think this library was originally written for 16MHz, and I'm not completely sure the shift to 8MHz, which it appears to do ok, is actually being done correctly. When the battery holder for it arrives, I plan to run this on a single 18650 with no regulator.
Thanks for any words of wisdom.