The circuit diagrams given(I'm assuming for Rotax engines) seem over complicated and 'ancient'. First of all, ignition coils, being Tesla coils, are among the first types of electronic transformers, which generally increase voltage, while decreasing amperage. Ignition coils have two coils each. The primary coil has thicker windings, with only 20 or 30 turns, and today usually runs at 12 volts(battery voltage). The secondary coil consists of much finer wire, but has hundreds of windings. This secondary coil usually runs at 15-25 thousand volts. The primary and secondary coils are not directly connected to each other.
For many years in the automotive world, the primary ign coil would be charged up at 12 volts by the car's battery, by the generator, or by the alternator. This charging would only take 5-10 thousandths of a second, depending on engine rpms. The car's distributor controlled this 'dwell' time as it rotated a lobed cam. The cam opened the points, thus briefly turning off the low-voltage current to the primary coil, and collapsing its electromagnetic field. The collapsing field then 'induced' a high-voltage current into the secondary ign coil, which fired the spark plug in the proper cylinder, a predetermined number of degrees before Top-dead-Center(also selected by the distributor lobes). A fairly large capacitor was connected to the primary coil circuit and to ground. In small 2-4 cylinder car engines, the capacitor was screwed to the outside of the distributor. In 6-8 cylinder engines, there was room for it inside the distributor, under the distributor cap. The capacitor was needed to prevent the 200 or so volts of primary back-voltage from oxidizing(burning up) the points prematurely in a couple hundred miles. Even with capacitors, the points would burned up in 6-12 thousand miles.