One question I had earlier was how can an analog CDI provide an advance curve? One answer I ran across on the all knowing Internet--use an "all pass" analog filter.
Ideal All Pass filters (as I was reminded by my papyrus copy of "Signals & Systems") don't attenuate signals, they just delay signals (shift phase) as a function of signal frequency. E.g. As the RPM goes up, the timing signal gets shifted.
AP filters can be made from a nightmarish combination of a ladder of RC filters and/or a network of choke coils (inductors).
Now I really, really want to cut a CDI apart
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