Hi Jules,
The triggering on 15 degrees before TDC should be about right for attraction mode. But it should switch off exactly at TDC !!
With 5 magnets on the wheel you have 72 degrees of rotation between pulses. With 15 degrees of pulse duration you would have a duty cycle of 15/72 or 20.8%. This is about ideal.
In order to trigger off at TDC there are several ways it do it. A 555 timer based circuit will work correctly at only a particular RPM because it is time based and not distance (degrees of rotation) based.
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