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Ignition coil question

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Connecteur:
I hope this isn't too far off-topic for this forum, but the Model T Ford had a trembler coil type ignition system. When activated by a timer, the trembler coil energized a buzzer. A condenser in parallel with the breaker points and coil formed a harmonic circuit that generated high voltage in the secondary coil which was boosted higher by the condenser and breaker points.  As long as the timer (rotary wiper switch) was activating the trembler coil, a high voltage current was sent to the spark plug.  Each cylinder had it's own trembler coil assembly.

There were two power sources in most cars that drove the ignition, a battery or a magneto.  The magneto was AC, so I am curious if AC impeded the performance of the ignition compared to DC.  I know some cars had dry cells used for easier starting, and a switch to select the magneto after it was running.  After 1919, the Model T got a wet cell battery, generator and a starter, but retained the magneto and trembler coil ignition until 1927.

HighVoltage:

--- Quote from: Connecteur on October 11, 2021, 03:56:04 pm ---I hope this isn't too far off-topic for this forum, but the Model T Ford had a trembler coil type ignition system. When activated by a timer, the trembler coil energized a buzzer. A condenser in parallel with the breaker points and coil formed a harmonic circuit that generated high voltage in the secondary coil which was boosted higher by the condenser and breaker points.  As long as the timer (rotary wiper switch) was activating the trembler coil, a high voltage current was sent to the spark plug.  Each cylinder had it's own trembler coil assembly.

There were two power sources in most cars that drove the ignition, a battery or a magneto.  The magneto was AC, so I am curious if AC impeded the performance of the ignition compared to DC.  I know some cars had dry cells used for easier starting, and a switch to select the magneto after it was running.  After 1919, the Model T got a wet cell battery, generator and a starter, but retained the magneto and trembler coil ignition until 1927.

--- End quote ---

And what is your question?

Connecteur:
How effective is AC compared to DC for creating good ignition with a trembler coil?

Circlotron:
With an AC supply there is going to be repeating dead spots in the supply voltage, and if this occurs at the exact moment you need a spark then things are going to have to wait until the voltage rises high enough to get that buzzer buzzing again. That is not a good thing. But then, neither is the entire ignition setup of a Model T. Except maybe for the continuous train of sparks at cranking speed. Not sure how much spark energy in those things. Any idea how much current is interrupted by the buzzer contacts? Actually, maybe the flywheel magnets are positioned so that the AC zero crossing point doesn't matter. I better go read up on these things.

bdunham7:

--- Quote from: Connecteur on October 12, 2021, 12:20:26 am ---How effective is AC compared to DC for creating good ignition with a trembler coil?

--- End quote ---

The magneto is not an AC source for the tremblers, it's a bit more complicated.

https://www.fordmodelt.net/downloads/Model%20T%20Ignition.pdf

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