Inductive Kickback

[synchro1]

I agree.

I would add though, that the cause of current flow through an inductor can be:
- an external current source,
- an external voltage source,
- an external magnetic flux source,
- the inductor itself, since a current flowing through an ideal shorted inductor will flow forever.

From Woopyjump:

"For me what I see on the scope is that at the end of the pulse, when the reed sharply opens, the current trace goes to almost  instantly (verticaly) to zero. And only AFTER this shut down,  begins the flybackspike.

So to me the current who build up the magnetic field is gone , totally dissipated, finished at the end of the pulse. He was totally used to precisely build the magnetic field. So he has no more direction at all.

Than it stays the expanded magnetic field around the coil (??) and what exactly happens at that point is ?? But  on the scope ,  suddenly a strong narrow  "high negative voltage" trace appears  and also a strong very very narrow and strong current trace (not shown on the pic) also. What does create this event is still puzzling to me.

If it is the collapsing of the magneticfield please explain the process with simple words if possible. But anyway to me that is a new current who has nothing to do directly with the one that created the magnetic field. It is what I call his "son".

[synchro1]

The current passes into the inductor; The inductor stores the current in a magnetic field; The current is cut off; The magnetic field collapses and a new current and voltage are generated; The new current and voltage share the same polarity! Stop trying to falsely maintain that the new voltage reverses polarity while the new current does something else!

Go back and look at Woopyjump's scope shots!

[citfta]

Simple test for Woopy.

Put one channel of your scope across the coil and the other channel across the 10 ohm resistor.  Now pulse the coil and watch the two waveforms.  Please post your results.

[synchro1]

Hi Tinman

There is really no sense for voltage to change polarity while the field is collapsing. Voltage and current have a strict relation between the two. Current always flow from higher voltage potential to a lower one and never the opposite even momentarily. As current keeps going the same direction after collapsing, the same is with voltage. Not only it doesn't alter its polarity, but also becomes magnitudes higher also momentarily like current does.

@Jeg,

Go back and have another look at Woopy's scope shots!

[synchro1]

Simple test for Woopy.

Put one channel of your scope across the coil and the other channel across the 10 ohm resistor.  Now pulse the coil and watch the two waveforms.  Please post your results.

@Citfta,

What's the voltage of the power source? What's the inductance of the coil?