Negative discharge effect

[Dave45]

Just my opinion, but I havent watched all your vids.

[ayeaye]

Yes the circuit is correct, thank you Dave45.

At left is a microcontroller, yes. KL25Z, a 32 bit ARM microcontroller, but can be any microcontroller.

The weird effect is, the source capacitor charges negatively (minus is up) the same as the charged capacitor, and they have almost the same voltage. But at that, back emf can only go to the charged capacitor, because the mosfet is closed during back emf. So it looks like that the coil still takes current from the source capacitor, when there is a voltage spike, but when that capacitor has no positive charge, it will be charged negatively.

This is the circuit diagram in the first videos, in the last video the circuit diagram was that:

[Dave45]

I think the pos bemf is passing through the transistor's diode and charging the backside of the cap.

[Dave45]

An npn transistor passes neg to the coil and into the neg side of your caps.
The bemf from a neg pulsed coil is pos and charges the pos side of your caps.

[Dave45]

irf 630 is avalanche rated, meaning its diode will pass pos current
http://www.vishay.com/docs/91031/sihf630p.pdf
Just my opinion but work it out for yourself
Check everything,