The xLEDs use a coil hooked up directly to an LED and uses the natural capacitance of the LED to form the tank circuit. That’s why the xLED options are so limited, each LED requires a custom coil that involves a lot of trial and error.
The NTAG I2C Plus chip (in the xSIID and on the test card) receives power from the field like a normal transponder and regulates it down to a constant 15mA at 3.1V output.
In theory yes… this is how some of those NFC Nail things with both NTAG213 and LED work… they have some passives and the chip and the LED to make it all work. It could be possible to make such a thing, and we may focus on that being an idea in 2021 for the Spark 2, Apex Max, and Apex Flex… just at a later time.
The concern I have is that those configurations tend to impact performance. For the Apex Flex it probably won’t be a big deal, but for the Max and Spark 2 it could be. We attempted this once with a version of the Spark 1 and the results were… unimpressive.
@Aoxhwjfoavdlhsvfpzha@Eriequiet this is already an option as a custom order… the flexNAIL??? (idk what it’s called). It’s a single NFC LED nail, potentially with resin (ordinary or with glow powder on top) encased in Amal’s magic goo.