Several proposals to measure the Planck’s Constant for didactical purposes, using the current – voltage (I-V) characteristics of a light emitting diode (LED) have been made quite regularly in the last few years. The reason is that the experiment can be done easily in any lab and the result are surprisingly good (±10%). The physical interpretation however is not completely clear and this has raised many discussions, which has been published almost with same regularity as the proposals themselves.