Inductive Kickback

[MileHigh]

Laurent,

I my opinion, if you can understand how an inductor and a mechanical flywheel are directly related, that will make all the difference.  So the challenge is to just understand that first, and then once you understand the concept, then you can apply it to understanding circuits.

You saw the "Woopy's Linear Track Experiment" drawing that I made?

Look at the attached image that I found on Google.  This is just a teaser, does the image look familiar?

MileHigh

[citfta]

Thank's a lot Citfta

Finally somebody answering directly my questions.

So let's go further if you don't mind.

in my question 3
you seems to agree that  the current builds up effectively the magnetic field which propels and gives  the kinetic energy to the rotor.
But is the current or his energy still stored in the magnetic field after the magnetic field has propelled the rotor ?? Any entropy ?

The magnetic field is maintained as long as there is power applied to the coil. When power is no longer applied the magnetic field begins to weaken as it tries to maintain the current through the coil.  If you continue to apply power after the current has reached the maximum value which is also when the field has gotten the strongest then any power after that is wasted as heat because of the resistance of the wire in the coil.  So you want the pulse to be just long enough to cause the current to reach its peak and that will also mean the field has reached its peak.  Then when you turn off power to the coil the kickback will be the strongest and can thus give the most power to the cap.

So in my question 4
you seems to say that the input energy could be  used 2 time ?
Yes by capturing that kickback spike and reusing it you can make your system more efficient.  I think Luc just posted some more videos about that today.

If you have time try the test I proposed for you earlier with a 2 channel scope.  You can see the polarity switch with scope channel that is across the coil and you can see the current continue flowing through the resistor with the scope channel across the resistor.  If you can set this up with a 555 timer or some other means to fire the coil regularly it will be easier to get the scope picture you want.

Thank's very much for your input and for this thread , because i have so much to understand

Laurent

[MileHigh]

For an inductor, you can measure the current flowing through it, and the voltage across it.

Look at the picture of the laboratory flywheel.  You can see there is a smaller disk so you can use your hands to spin the flywheel.

When you apply voltage across an inductor, the current does not flow instantly.  Instead, it slowly rises.

If you have a stationary flywheel, and then you want to make it spin by applying torque to it with your hands, it does not spin at full speed right away.  Instead, the rotational speed slowly rises.

This is the first thing you have to understand:

Applying voltage to a coil makes the current start to flow, starting from zero.  Voltage is like "pressure" on the coil.
Applying torque to the flywheel makes the flywheel spin, starting from zero.   The torque is a pressure on the flywheel.

Therefore voltage is like torque.

If you can understand that, it's a good start.

[shylo]

Hi all,
If you take a single coil , and pass a magnet over it , as the magnet approaches it induces a potential (voltage) correct?
There is no current if the ends of coil aren't connected (open) correct?
If not open but connected to a load current will flow. correct?
But when the magnet is approaching the coil it builds , hits it's peak then builds in the opposite direction, short the coil right after the peak (disconnect load and short coil) then reconnect load.
That gives twice the work out of the coil.
Now  have recovery diodes and caps to collect the short, for both pulses.
Passing a magnet over a coil produces two pulses.
When the magnet is at the center of the coil that is where you short the coil leads together removed from the load , reconnect and do it again, before the passing magnet leaves(or stops influencing the coil)
Then short again.
artv

[synchro1]

What's wrong with this picture? The arrow in (c) looks llike it's moving in the same direction as (b) through the inductor. This is an illusion caused by confusing path with current direction.