Using the neutral wire mod described in this thread, I've found the latest version of Philips 457036 65W equiv reflector LED randomly flickers. Connecting an oscilloscope between the blue load wire on the switch and neutral white, I get this:
Notice the weird spiky dips near the peak of each pseudo-sine wave. Sometimes the spikes disappear and the peaks become narrow:
The scope shows the narrowed peaks have lowered Vrms to 8.4 (which is 84V on a 10X probe) which I think explains the flickering dimming. If I connect either of two older, 100W equivalent omnidirectional LEDs, I get a more normal looking sine and no flickering:
Notice Vrms reads 11.4 (114V) as expected for a 110-120V device.
I've tried three different Philips 457036 and two different modified X10 switches and each has the same problem.
I also found that an unmodified X10 switch does not have the flickering problem, but it leaves the light on dimly when the switch is off.
Here's a wiring diagram of the neutral wire modification:
Wires were cut at two sets of green Xs and new connections are represented by green lines.
Here's the completed mod (I desoldered the short end of the 330k resistor and reused it instead of adding a new 330k, and the neutral wire is yellow):
Any ideas how the flickering might be fixed?