Magneto question

[rotorwrench]

A basic magneto will fire off of each polarity change on a magnet rotating passed its E-gap where the north pole changes to the south pole of that rotating magnet. The trembler coils make things a little different than a basic magneto coil. This coil can either fire off of the magnet polarity change or it can fire off on the collapse of the magnetic field internal to the unit when running on direct current of a battery.

Running off of a DC battery, it needs the vibrator points to simulate the polarity change with half wave pulsating direct current or there will be no high tension firing of the spark plug. Each vibration cycle causes the build up and collapse of the magnetic field in the coil core which forces an induction to the high voltage output to the spark plug for a shower of sparks while the vibrator is buzzing. No buzzing, no spark at all.

The vibrator draws current any time the timer is grounding its circuit. To get peak efficiency out of the vibrator circuit that operates the points, the current draw has to be controlled or there can be double sparking and/or excessive heating in the primary coil circuit. This is where the current draw adjustment is important. It doesn't care what the voltage is. You can run off either a 6-volt battery or a 12-volt battery it a person wants to. The vibrator circuit won't function on AC so when the switch is on Magneto, it doesn't function.

The Model T magneto has more magnets than it needed to operate the ignition system but Ford also used it for lighting before the starter and generator systems started to show up in 1919. The ignition cycle of the engine still gets several pulsed sparks from the magneto when firing each cylinder but not as many as it gets from the battery power. The difference though is that the mag gives an increasingly hotter spark as the rpm rises. The battery ignition is limited to its power source and what it takes to function the vibrator & primary coil efficiently.