At what point does Back EMF occur?

[Farmhand]

Just speaking of a single coil. Immediately when the current begins to flow from applied EMF when the switch is closed, there is CEMF generated to oppose it. In a bedini energiser the current loop is a closed loop including the source battery when the switch is closed current flows in the entire loop it must as far as i can tell.

When the switch is open the field collapses out of the now open loop to the charge battery. The current through the charge battery would circulate back to the coil through the source battery positive terminal. And the voltage rises to overcome the resistance as cifta points out. But if the charge battery is disconnected or the resistance is very high or maybe if the frequency is very, low it seems the energy could go backwards to the source battery if it had time. Hence the source battery charging effect seen by some when chopping current to coils.

Cheers

[Joit]

When the switch is open the field collapses out of the now open loop to the charge battery. The current through the charge battery would circulate back to the coil through the source battery positive terminal.

I thought something similar, that the Charge Battery gets charge from the Impuls from Plus, but it does not make much sense, because you have the Coil as a Resistor between plus Charge and Minus - Positive, and therefor a lower Potential at the End from the Coil, at Emitter Side. The Impuls back happend through the Charge Batterie and ended at the Cathode from the Diode, there, where Plus Charge is connected to the Diode. It would be impossible to charge a Batterie that Way without breaking the Circuit.
And it even makes more less sense, that the Collapse happens from the End of the Coil to the Beginning, through the Batterie and again back to the End from the Coil.