Inductive Kickback

[seychelles]

So sooory i have been shouting haven't i..

[tinman]

This thread is to discuss what direction the current flows during inductive kickback.  Or to put it another way, as the magnetic field collapses which way does the current flow?

The definition of an inductor is that an inductor opposes change in current flow.  This would imply that as voltage is removed from an inductor the inductor would then try to keep the current flowing in the same direction until the magnetic field is exhausted.  This can be proven with experimentation.

So let the discussion begin.  Do you agree or disagree with this description of how an inductor works?  Please explain why you agree or disagree.  Please keep your comments to a technical discussion and not get into name calling if you disagree with someone.

Respectfully,
Carroll

To make things clear,it should be said that when the current source is interrupted,the current will want to keep flowing through the inductor-not if the voltage is removed.

It is said that an inductor is a current source,but that has never sat well with me,and i consider an inductor and a capacitor as a means to store energy,which can deliver power-not just current or voltage.

The flyback from an inductor can deliver power to a load,and the value/resistance of that load will determine as to what the voltage and current values will be with a set inductor. E.G-if the resistance of the load is low,then the flyback voltage will be low,and the current high. If the resistance of the load is high,then the flyback voltage will be high ,and the current low.

It should also be noted that the lower the resistive value of the load being placed on the flyback,the longer the magnetic field takes to fully collapse around the inductor. This results in a higher current due to the slower collapsing field,but a lower voltage for the same reason-the slower changing magnetic field with time. The higher the value of the resistive load on the flyback,the quicker the magnetic field around the inductor will collapse. This results in a lower current but a higher voltage due to the faster changing magnetic field with time.

[tinman]

2

When the current source to an inductor is interrupted, the current will continue to flow through the inductor in the same direction,but the voltage across that inductor will invert. This is how the simple circuit below is able to work,and the LED can be lit from the flyback<--im guessing you guys want to use the term !flyback! so as to keep it simple?.

Diagram 1 shows the switch closed,and current flows from the battery into the top of the inductor,and out the bottom of the inductor,and into the negative of the battery. At this point in time,i also assume that we will stick to conventional current flow throughout this thread-so as to keep it simple?.

Diagram 2 shows the current flow through the inductor,and voltage polarity across that inductor the moment the switch becomes open. This current flow,and voltage polarity will remain the same until such time as the magnetic field around the inductor has fully collapsed-all stored energy has been depleted. We know the current flowing through the inductor must be in the same direction,and the voltage must have inverted in order for the LED to light.

[Jeg]

Hi guys

When the switch opens, inductor will try to keep its magnetic field alive, and to retain its magnetic poles at the same place as when the switch is closed. There is no other way for this to happen than the current to keep going on same direction as before. This is simple physics. What path it will take depends on the circuitry. In this example bemf  just can not return to the negative of the battery because the circuit is open!!! It will go through diode because the circuit closes through the capacitor back to the base of the inductor.
Sometimes our minds get stack in simple matters. It happens to all of us.

[synchro1]

To make things clear,it should be said that when the current source is interrupted,the current will want to keep flowing through the inductor-not if the voltage is removed.

It is said that an inductor is a current source,but that has never sat well with me,and i consider an inductor and a capacitor as a means to store energy,which can deliver power-not just current or voltage.

The flyback from an inductor can deliver power to a load,and the value/resistance of that load will determine as to what the voltage and current values will be with a set inductor. E.G-if the resistance of the load is low,then the flyback voltage will be low,and the current high. If the resistance of the load is high,then the flyback voltage will be high ,and the current low.

It should also be noted that the lower the resistive value of the load being placed on the flyback,the longer the magnetic field takes to fully collapse around the inductor. This results in a higher current due to the slower collapsing field,but a lower voltage for the same reason-the slower changing magnetic field with time. The higher the value of the resistive load on the flyback,the quicker the magnetic field around the inductor will collapse. This results in a lower current but a higher voltage due to the faster changing magnetic field with time.

@Tinman,

The speed that the Reed switch contacts separate determines the "Flyback Voltage".