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Ignition coil question

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bdunham7:

--- Quote from: Connecteur on October 12, 2021, 04:10:51 pm ---My question would be whether such a variable AC power source might impair the creation of a spark at times, compared to a DC battery source.

--- End quote ---

You need to carefully reread the reference I posted and then understand the magneto is not simply a power source for the tremblers.  There's no trembling in magneto mode.  Instead, the magneto pulse is what determines the timing of the spark and the coil/point assembly simply follows the magneto and produces a single spark in response to the magneto current pulse.  I suppose you could say that instead of 'trembling' there is a single 'quiver' per spark.

bdunham7:

--- Quote from: floobydust on October 12, 2021, 06:04:44 pm ---If the magneto was at a zero cross, there will be no spark possible even though the Timer is commanding a spark to start. Ford was on top of this, the magnet positions were synchronized on the crankshaft and advanced 7 degrees. But still deadspots exist. There's also like 10 revisions to the magneto design.

--- End quote ---

It's easier to think of the timer in magneto mode as a window or gate--like a distributor--rather than a 'command' as it is in battery mode. The actual sparks and their timing are a product of magneto arrangement, the timer just determines which ones happen and which don't. 

floobydust:
I thought the vibrator still was operating when under magneto power? As long as sufficient voltage is there for it to oscillate during peaks. I'd have to hear one operating, but say 500Hz bursts at most possible 16 per crank rev?

edit2: Then the ignition timing would change - spark(s) when Timer contact closes to instead a siungle spark when it opens. One article says the engine normally speeds up when switched from battery to magneto, I'd think that is more advance but who knows with this old engine that seems to run with way retarded spark timing overall.
The vibrator is part of the coil's core so always there I think, once flux builds up the contacts open. Hmm.

Connecteur:
Research is telling me that most people think that the magneto makes the car run better than on battery, which is counter to what I had expected.  I suppose the voltage from the magneto is usually higher than the 6 volts of a battery.  Someone suggested that a 12V battery made the car run better.  I suppose it proves that a variable AC source doesn't impair the functioning of a trembler coil.

I haven't done the math, but I expect that a 200Hz buzzer would deliver many sparks in the part of the cycle where the ignition for that cylinder was active.

floobydust:
It's multispark but weak sparks, when the vibrator is running. Really long duration.
If it changes over to a single spark mode i.e. Kettering (one strong spark) when running from magneto, then duration is much less, no backfires.
Since the vibrator's armature is moved by the coil's flux, there is a limit to the flux density regardless of power source, I think. This would imply it's some timing change that makes them run "better".

It must have been unreliable, or the Model T sold huge volumes. There were many companies making Timers and coils, they're all over antique shops and eBay.
It's interesting the magneto is axial flux, flat wire edge wound technology.

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