[TR] Electronic ignition systems

[Randall]

> Don't forget the condenser

I wasn't.  According to a white paper written by Dan Masters, the condenser
limits the rate of rise of the primary to around 50 amps per millisecond.
I'm not sure offhand exactly how that translates into delay before the spark
happens, but since the primary current is less than 5 amps, it should
provide an upper bound of 100 microseconds for the primary current to be
zero, which should be at least somewhat after the spark happens.

At 6000 rpm, the crank only moves 36 degrees per millisecond, or 3.6 degrees
in 100 us.  Enough to make some difference in performance, but unless your
scope is a lot better than mine, not enough to see on a scope.

And my point before was that, since advance curves are typically determined
empirically, the advance curve compensates for the delay caused by the
condenser/capacitor.  If you remove the delay, the curve becomes too
aggressive.

FWIW, I found a CDI patent that states with the CDI, the primary rise time
is limited to approx 2 us, but that the coil delays this to 15 us at the
output.

-- Randall