The type of an LED power driver (i.e., a magnetic transformer or an electronic transformer) is determined by manipulating the AC voltage produced by the power driver so that it may be analyzed and the type of power driver reliably determined. In various embodiments, a system for detecting an AC power supply type includes a circuit for monitoring a negative half or a positive half of an output voltage of the AC power supply and an analyzer for determining the AC power supply type based at least in part on a presence or absence of an envelope in the monitored output voltage.