Jim Yanik wrote in news:Xns99E6EF43834AFjyanikkuanet@64.209.0.84:
Found a schematic online. This is a little over my head, but I'm trying to grasp it anyway.
As I understand it, the IC drops the base current at the correct time, causing flow to stop between emitter and collector. This is the action of switching the transistor off, forcing the field collapse that creates the HT current in the coil.
According to some pages I'm finding, the current-limiting resistor changes its value as *voltage* goes up, which is how the IC knows what's happening.