still can't understand why triggering the box on the falling edge it won't run. Only thing I can come up with is that the spark happens later, and the rotor is past the cap terminal at that point
Or they are backwards in the use of their terminology.
the mysteries of circuit design can make you scratch your head. Been working on electronics since 83 and when I run into this situation I just go with what works and not worry about the rest. What maybe happening is that you are feeding it the negative going portion first and it is looking to trigger off a positive signal, either the leading or trailing edge of that positive going signal. It may have a signal clamping circuit designed to protect the input that is triggered by the negative going circuit, it essentially shorts the input to ground to prevent damage and doesn't release in time to use the positive going signal that comes later. Just a guess though. Even though we like to think electronics are instantaneous, they really aren't. Though they do work faster than we can see it happen it has built in lag that can sometimes rear it's ugly head.
