I continue to find new things this little gadget can do.  Two CRAY stacks ganged together synchonize their outputs and settle down to spark every other frame.  The device perfectly flips back and forth from one side to the other each and every frame.  

Very surprising.

Not every element can accept fast sparks.  But CRAY and ARAY can.  CRAY won't accept spark every other frame.  Looks like only ARAY can.