Storing Cookies (See : http://ec.europa.eu/ipg/basics/legal/cookies/index_en.htm ) help us to bring you our services at overunity.com . If you use this website and our services you declare yourself okay with using cookies .More Infos here:
https://overunity.com/5553/privacy-policy/
If you do not agree with storing cookies, please LEAVE this website now. From the 25th of May 2018, every existing user has to accept the GDPR agreement at first login. If a user is unwilling to accept the GDPR, he should email us and request to erase his account. Many thanks for your understanding

User Menu

Custom Search

Author Topic: Inductive Kickback  (Read 156560 times)

citfta

  • Hero Member
  • *****
  • Posts: 1050
Re: Inductive Kickback
« Reply #45 on: November 20, 2015, 08:40:05 PM »
@Citfta,

I can adjust the values to produce a spark across the Reed contacts.

I doubt you can get the reed to arc with a 100 load resistor.  Not unless you are using a much higher voltage than 12 volts.

synchro1

  • Hero Member
  • *****
  • Posts: 4720
Re: Inductive Kickback
« Reply #46 on: November 20, 2015, 08:42:27 PM »
I doubt you can get the reed to arc with a 100 load resistor.  Not unless you are using a much higher voltage than 12 volts.

@Citfta,

We're not mind readers. Upload a video. Can you explain why the "Flyback Spike" would arc the Reed contacts and travel back to the positive electrode of the power source to begin with?

citfta

  • Hero Member
  • *****
  • Posts: 1050
Re: Inductive Kickback
« Reply #47 on: November 20, 2015, 08:54:38 PM »
@Citfta,

We're not mind readers. Upload a video. Can you explain why the "Flyback Spike" would arc the Reed contacts and travel back to the positive electrode of the power source to begin with?

It is NOT traveling back.  It is trying to continue on.  That is the basic definition of an inductor.  It opposes change in current flow.

Instead of me posting a video why don't you do the simple test I proposed using Tinman's circuit and then measure the voltage on the cap so that you can see for yourself that the current does not reverse.  Did you think about how current has to flow inside a battery to complete the current path?  HINT  It has to be opposite of the voltage polarity shown by a meter.

synchro1

  • Hero Member
  • *****
  • Posts: 4720
Re: Inductive Kickback
« Reply #48 on: November 20, 2015, 09:11:26 PM »
It is NOT traveling back.  It is trying to continue on.  That is the basic definition of an inductor.  It opposes change in current flow.

Instead of me posting a video why don't you do the simple test I proposed using Tinman's circuit and then measure the voltage on the cap so that you can see for yourself that the current does not reverse.  Did you think about how current has to flow inside a battery to complete the current path?  HINT  It has to be opposite of the voltage polarity shown by a meter.

@Citfta,

I'm in political exile in Costa Rica. What do you mean it's not traveling back? You pretend it's really trying to follow the path you outlined in your schematic? Come on, put your thinking cap on.

You don't think you might have your DMM electrodes or scope probes reversed?

synchro1

  • Hero Member
  • *****
  • Posts: 4720
Re: Inductive Kickback
« Reply #49 on: November 20, 2015, 09:22:49 PM »
@Citfta,

This is my all time favorite pulse motor build by Igor Moroz; I've watched it at least a hundred times. It's as close to a self runner as anything I've ever seen and it's simpler then anyone can imagine. I love it. Please look at it more then once. It's only two minutes long. Study it:

https://www.youtube.com/watch?v=vWvI7T7h3tk

citfta

  • Hero Member
  • *****
  • Posts: 1050
Re: Inductive Kickback
« Reply #50 on: November 20, 2015, 09:29:52 PM »
Two people believing the wrong thing does not make it true.  I have had this discussion several times before in the past.  Some have learned and some have not.

MileHigh

  • Hero Member
  • *****
  • Posts: 7600
Re: Inductive Kickback
« Reply #51 on: November 20, 2015, 09:31:50 PM »
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.

You are right about the current not changing direction but you are not right about the magnitude of the current.

When you disconnect the power source from the coil, whatever the magnitude of the current flowing through the coil is, that's the initial amount of current that will flow through the load.

If you have one amp flowing through the coil and you disconnect your power source and the load is a 100-ohm resistor, then initially the current flow through the load will be one amp and the voltage across the load will be 100 volts.  If the load is 5000 ohms, then initially the current flow through the load will still be one amp and the voltage across the load will be 5000 volts.

woopy

  • Hero Member
  • *****
  • Posts: 608
Re: Inductive Kickback
« Reply #52 on: November 20, 2015, 09:42:07 PM »
Hi Cifta and Synchro and all

If i posted above it is not to get  what i can get from all text books about physic.

My questions are  very clear :

1- at the end of the pulse, on the scope shot, the input current from the power source has totally vanished  yes or not ?

2- The current has built a magnetic field in or around  the inductor and this magnetic field has been " used "  to propel the rotor magnet yes or not ?

3- so the current is not stored in the magneticfield but has been used the give the rotor magnet a kinetic energy yes or not ?

4-So if the magneticfield  collapses and by shrinking it crosses the wires of the coil and redo a new current does it mean that the magneticfield can be used twice yes or not ?

And just for the dessert

A small video showing that the flybackspike can be really powerfull and destroying as  every body knows very well

https://youtu.be/TAx7Y0UIyHA

good night at all

Laurent

citfta

  • Hero Member
  • *****
  • Posts: 1050
Re: Inductive Kickback
« Reply #53 on: November 20, 2015, 09:43:56 PM »
You are right about the current not changing direction but you are not right about the magnitude of the current.

When you disconnect the power source from the coil, whatever the magnitude of the current flowing through the coil is, that's the initial amount of current that will flow through the load.

If you have one amp flowing through the coil and you disconnect your power source and the load is a 100-ohm resistor, then initially the current flow through the load will be one amp and the voltage across the load will be 100 volts.  If the load is 5000 ohms, then initially the current flow through the load will still be one amp and the voltage across the load will be 5000 volts.

Don't you want to rethink that last paragraph?  You have just given (if true) the formula for OU.  In your first example you are putting 100 watts into the load.  In your second example you are putting 5000 watts into the load.  Where did that extra 4900 watts come from?

verpies

  • Hero Member
  • *****
  • Posts: 3473
Re: Inductive Kickback
« Reply #54 on: November 20, 2015, 09:49:04 PM »
If you have one amp flowing through the coil and you disconnect your power source and the load is a 100-ohm resistor, then initially the current flow through the load will be one amp and the voltage across the load will be 100 volts.  If the load is 5000 ohms, then initially the current flow through the load will still be one amp and the voltage across the load will be 5000 volts.
That's why they call it a current source - constant current regardless of the load resistance.

P.S.
That Igor guy and Synchro are wrong about the current through the inductor reversing when the inductor is opened.
How do I know? -  I did the lab work and I can distinguish when my scope is measuring current vs. when it is measuring voltage.

verpies

  • Hero Member
  • *****
  • Posts: 3473
Re: Inductive Kickback
« Reply #55 on: November 20, 2015, 09:52:28 PM »
In your second example you are putting 5000 watts into the load.  Where did that extra 4900 watts come from?
No, only the initial instantaneous power dissipated into the load (the 100Ω resistor) is I2R.

The energy stored in the inductor is ½LI2 in both cases

MileHigh

  • Hero Member
  • *****
  • Posts: 7600
Re: Inductive Kickback
« Reply #56 on: November 20, 2015, 09:55:56 PM »
@Citfta,

This is my all time favorite pulse motor build by Igor Moroz; I've watched it at least a hundred times. It's as close to a self runner as anything I've ever seen and it's simpler then anyone can imagine. I love it. Please look at it more then once. It's only two minutes long. Study it:

https://www.youtube.com/watch?v=vWvI7T7h3tk

Yes I looked at the clip and Igor is dead wrong.   A few years ago he was making clips where he was always saying that his diodes were redirecting current back to the source battery.  I pointed out to him that that was wrong and he acknowledged it and then just shrugged it off.  He probably had at least a dozen clips with that mistake in them.

It's safe to assume that Igor is just an ordinary guy, an amateur, so don't make the mistake of taking what he says in his clips as always being true.

Here is a comment on Igor's clip from three years ago:

<<< @Mopozco Great, thanks for sharing results. The collapsing field of a coil wants to keep current flowing in same direction, coil behaves like battery in series with your 1.5V battery ~(-)batt(+)~~~(-)coil(+)~. Please confirm direction of LED on your drawing. Is LED cathode connected to coil so that when current from collapsing field at higher voltage (bemf) exceeds LED Vf it flashes it? This would keep the current flowing in the same direction not in opposite direction as shown on your drawing.  >>>

The guy is probably right and Igor had the LED in the opposite direction that he thought it was.  Alternatively, I don't know if an LED will light up if you slam current through it in the wrong direction but you never know.

It all goes back to the messed up culture on the forums of being too polite to correct your peers when they make a mistake.  It creates a regimen of enforced foolishness and stupidity.  I can't tell you how many times I have seen inane ridiculous postings by people and people on the forum say things like, "Thanks for your interesting ideas!"  It's ridiculous and totally counterproductive.

I just posted that Tinman was wrong about the current flow in an inductor.  Chances are if I didn't post the correction, then nobody would have corrected him.  That would turn what is supposed to be an informative educational thread into more uncorrected disinformation, messing up people's understanding of basic basic electronics, yet again.

synchro1

  • Hero Member
  • *****
  • Posts: 4720
Re: Inductive Kickback
« Reply #57 on: November 20, 2015, 09:57:49 PM »
Hi Cifta and Synchro and all

If i posted above it is not to get  what i can get from all text books about physic.

My questions are  very clear :

1- at the end of the pulse, on the scope shot, the input current from the power source has totally vanished  yes or not ?

2- The current has built a magnetic field in or around  the inductor and this magnetic field has been " used "  to propel the rotor magnet yes or not ?

3- so the current is not stored in the magneticfield but has been used the give the rotor magnet a kinetic energy yes or not ?

4-So if the magneticfield  collapses and by shrinking it crosses the wires of the coil and redo a new current does it mean that the magneticfield can be used twice yes or not ?

And just for the dessert

A small video showing that the flybackspike can be really powerfull and destroying as  every body knows very well

https://youtu.be/TAx7Y0UIyHA

good night at all

Laurent

@Laurent,

Wear your welding glasses!

citfta

  • Hero Member
  • *****
  • Posts: 1050
Re: Inductive Kickback
« Reply #58 on: November 20, 2015, 09:58:26 PM »
Hi Cifta and Synchro and all

If i posted above it is not to get  what i can get from all text books about physic.

My questions are  very clear :

1- at the end of the pulse, on the scope shot, the input current from the power source has totally vanished  yes or not ?
Yes

2- The current has built a magnetic field in or around  the inductor and this magnetic field has been " used "  to propel the rotor magnet yes or not ?
Yes

3- so the current is not stored in the magneticfield but has been used the give the rotor magnet a kinetic energy yes or not ?
The current builds the magnetic field and the magnetic field gives the rotor magnet the kinetic energy

4-So if the magneticfield  collapses and by shrinking it crosses the wires of the coil and redo a new current does it mean that the magneticfield can be used twice yes or not ?
Yes that is why we can send current to the cap after the reed switch has opened.

And just for the dessert

A small video showing that the flybackspike can be really powerfull and destroying as  every body knows very well

https://youtu.be/TAx7Y0UIyHA

good night at all

Laurent

synchro1

  • Hero Member
  • *****
  • Posts: 4720
Re: Inductive Kickback
« Reply #59 on: November 20, 2015, 09:59:58 PM »
Yes I looked at the clip and Igor is dead wrong.   A few years ago he was making clips where he was always saying that his diodes were redirecting current back to the source battery.  I pointed out to him that that was wrong and he acknowledged it and then just shrugged it off.  He probably had at least a dozen clips with that mistake in them.

It's safe to assume that Igor is just an ordinary guy, an amateur, so don't make the mistake of taking what he says in his clips as always being true.

Here is a comment on Igor's clip from three years ago:

<<< @Mopozco Great, thanks for sharing results. The collapsing field of a coil wants to keep current flowing in same direction, coil behaves like battery in series with your 1.5V battery ~(-)batt(+)~~~(-)coil(+)~. Please confirm direction of LED on your drawing. Is LED cathode connected to coil so that when current from collapsing field at higher voltage (bemf) exceeds LED Vf it flashes it? This would keep the current flowing in the same direction not in opposite direction as shown on your drawing.  >>>

The guy is probably right and Igor had the LED in the opposite direction that he thought it was.  Alternatively, I don't know if an LED will light up if you slam current through it in the wrong direction but you never know.

It all goes back to the messed up culture on the forums of being too polite to correct your peers when they make a mistake.  It creates a regimen of enforced foolishness and stupidity.  I can't tell you how many times I have seen inane ridiculous postings by people and people on the forum say things like, "Thanks for your interesting ideas!"  It's ridiculous and totally counterproductive.

I just posted that Tinman was wrong about the current flow in an inductor.  Chances are if I didn't post the correction, then nobody would have corrected him.  That would turn what is supposed to be an informative educational thread into more uncorrected disinformation, messing up people's understanding of basic basic electronics, yet again.

@Milehigh,

The LED is reverse biased in Igor's video. This is the trick of the build. You have too much to say about this intrepid inventor for someone who never uploaded even so much as one test video of any kind.

You pasted some copied comments from Igor's video, but you neglected to copy this one by Lidmotor:

"I have been doing this same thing and it seems to work really well.  It saves the reed switch contacts also".