Inductive Kickback

[MileHigh]

Laurent,

Please see the attached image where I annotated one of your scope traces to illustrate the flywheel analogy.

There is also a very very important lesson to be learned here that I previously mentioned.  Let's talk about an electrical coil and the negative voltage spike.  What is the source of the negative voltage spike? Is it the coil that is generating the negative voltage spike, or is it the load that is generating the negavive voltage spike as a reaction to the pulse of current from the coil?

Now let's go back to the flywheel analogy.   We know that the reason there is a big spike of negative torque on the flywheel is because the brake pads clamp down hard on the flywheel, just like disk brakes in a car.  The brake pads are the source of the big spike of negative torque on the flywheel. The brake pads are the mechanical load on the spinning flywheel.

That is telling you that for an electrical coil, the coil itself is not the source of the negative voltage spike.  Rather, it is the load that generates the negative voltage spike as a reaction to the pulse of current from the coil.

[synchro1]

I have asked Stefan to lock this thread as it no longer serves a useful purpose.  I have also asked that synchro be put on notice for his childish behavior.

@Citfta,

Oh! Please don't hurt me boss, I'm jus da poo boss's nigga boss! Big bully Mumzy Jr. Member "Carroll" Lockin the Thread down now, huh!

[MileHigh]

@MH and Verpies.
As i was saying-looking at the scope shot,you can see that the peak current during the on time is more than the instantaneous current during the off time. You can see the current drop in value at switch off.

Yes, you can see the "step down" that the current takes at switch off.  You notice it all makes sense because for a short time you see the voltage trace is near-vertical and negative at that time.  That corresponds to a short powerful impulse of negative torque on a flywheel so that the RPM takes a near-instant step down in speed.

[synchro1]

I'm curious......Are you aware of a method which can be applied to electro mechanical devices which grants one the ability to produce "voltage spikes", a method which does not put the brakes on the prime mover? 




Regards

@Erfinder,

"The purpose of a "flyback transformer" in a monitor or television is to generate high voltage about 24 kilovolts dc to picture tube or crt".

[gyulasun]

Hi Laurent,

Thanks for answering where the 1 Ohm resistor was placed and for the scope shots too. This helps me answer.

I attached a schematic I fabricated from one of tinman's and your drawings. I want to show where is a correct place to insert the 1 Ohm resistor to monitor the current in the coil in both situations i.e. when the reed switch is ON and when the reed switch is OFF. 
This is because as you described the placement of the 1 Ohm (i.e. between the reed and the 5 mH coil) it was good for seeing the input current while the reed was ON. And after the reed switch was off,  the coil current could not be seen at the same 1 Ohm position because the 1 Ohm was already in an open circuit towards the reed.

If you feel like to repeat the test as per this schematic, yellow trace would show the current in the coil, blue trace would be the voltage across the coil, the Ref point on the negativ battery would be the scope common crocodile grnd.

Thanks, 
Gyula