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just transients
NPN transistors are ideal for low-side switching
PNP transistors are ideal for high-side switching
in the case of low-side switching, as with a standard Bedini SG circuit:
From the perspective of the transistor looking at the nearest end of the coil, closing the switch creates a transient in which the near side is negative-charging which is unavailable for use in present circuit topology(trigger winding might absorb some of it.) Opening the switch creates a transient in which the near-side is positive-charging, which would prefer the path offered by the diode to charge a capacitance *above* the source positive potential by reacting against a "virtual ground" appearing with the transient at the far end of the coil.
Invert all of the above polarity notations for high-side switching...
PNP transistors are ideal for high-side switching
in the case of low-side switching, as with a standard Bedini SG circuit:
From the perspective of the transistor looking at the nearest end of the coil, closing the switch creates a transient in which the near side is negative-charging which is unavailable for use in present circuit topology(trigger winding might absorb some of it.) Opening the switch creates a transient in which the near-side is positive-charging, which would prefer the path offered by the diode to charge a capacitance *above* the source positive potential by reacting against a "virtual ground" appearing with the transient at the far end of the coil.
Invert all of the above polarity notations for high-side switching...