The idea behind is - after first pulse you let BEMF to reach maximum
and hit with current from transistor again on its peak time so
the magnetic domains when coming back wil be supported by current and
voltage from BEMF WILL ADD with current from transistor so C28 cap
will charge from much higher voltage on positive half-cycle.
The LEDs are powered from BEMF. After this pulse you need to let ferrite's
magnetic domains to return into first position.
This is why there is low frequency in akula's ferrite case.