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Author Topic: Effects of Recirculating BEMF to Coil  (Read 59122 times)

gotoluc

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Effects of Recirculating BEMF to Coil
« on: July 03, 2009, 12:24:29 AM »
Hi everyone,

it has been a while since I posted new information but yet again here is another interesting effect I have come upon.

As usual, the video explains most of what you would need to know if you would like to try this.

Video Link: http://www.youtube.com/watch?v=STI3koWbzE4

I personally think it is worth much more investigation to come to understand why the BEMF has so much more effect on a magnet when re-circulated back in the coil then the original energy input ???

Could this be what Ed Gray did?

If anyone does understand this and can explain it, please do not hold back!

Thanks for looking

Luc

poynt99

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Re: Effects of Recirculating BEMF to Coil
« Reply #1 on: July 03, 2009, 01:40:49 AM »
Hi Luc.

Thanks for the video.

What you are seeing there is a conventional effect.

I am assuming that what you mean by "feeding the inductive kickback (or BEMF as most call it) back into the coil", is that you are placing the diode (flyback diode) across the coil. If so then yes you are recirculating the coil current.

Pulsing an inductive coil is a two phase process; energize, and de-energize. I think WHEN these two phases occur is obvious, but what isn't always obvious is that with a flyback diode across the coil, during the de-energize phase roughly the same amount of current keeps circulating, and in the SAME direction it was in the energize phase.

What this means is that the effective magnetic field produced by the coil is "ON" for roughly twice the amount of time it is when the diode is not present. This would have a marked effect on the neo magnet sitting on top of it, and that effect results in more lift on the magnet.

What happens when the diode is absent from the circuit is the IK results in very little current, but a large inverted voltage spike. This does not produce a magnetic force on the neo magnet because with inductors (coils), the magnetic field strength is proportional to the current through it.

Regarding the current measurement with and without the diode, I doubt either case is accurate with that meter and with the wave forms it's measuring.

Regards,
.99

gotoluc

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Re: Effects of Recirculating BEMF to Coil
« Reply #2 on: July 03, 2009, 02:47:58 AM »
Hi .99,

thanks for looking and posting your understanding of what is going on in the coil.

I'm looking for others to replicate this simple circuit experiment and hope you have time to try it! as you will find that the current does indeed drop ;).... I have not only used the meter in the video to confirm this. I used that meter in the video because it was simple. Try the experiment and post what you find, just make sure to use short duty cycles to see the effect.

Luc

poynt99

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Re: Effects of Recirculating BEMF to Coil
« Reply #3 on: July 03, 2009, 05:38:05 AM »
If anyone does understand this and can explain it, please do not hold back!

Thanks for looking

Luc

Hi Luc.

No offense, but there's no need for me to try the experiment :) I have a good understanding of currents in coils and my experiment efforts are already spoken for. I offered to share this knowledge to help explain what you are seeing in your experiment.

Explaining what your meter is interpreting is a little more complex, but I will get to that a little later.

In the mean time I would encourage you to place your scope probe across the meter leads in order to get an idea what the meter is reading, or trying to read ;) This might also help make sense of the difference between diode and no diode. Could you post a scope shot?

.99

poynt99

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Re: Effects of Recirculating BEMF to Coil
« Reply #4 on: July 04, 2009, 04:30:30 PM »
Luc,

Try this.

Do your test with and without the diode feedback again, but this time hold the magnet down against the coil (so it can not vibrate or float) for both.

Observe the current reading on the meter. Does it still read lower for the case where the diode is in-circuit?

.99

gotoluc

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Re: Effects of Recirculating BEMF to Coil
« Reply #5 on: July 04, 2009, 11:42:53 PM »
Hi .99 and everyone,

@.99, the test you have suggested have been done before I started this topic. I have been testing this for the past 7 days. I do appreciate your input and have made a new video to which I dedicated a large part to demonstrate to you by using a resistive load that the current does indeed drop slightly when the Inductive collapsing field is recirculated back into the coil.

To everyone else, I am not getting much feedback from the rest of you. Is there something that I'm missing or misunderstanding here. Please be honest and share your thoughts :)

New video: http://www.youtube.com/watch?v=_WW8z36n6z8

Luc

powercat

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Re: Effects of Recirculating BEMF to Coil
« Reply #6 on: July 05, 2009, 02:16:47 AM »
Hi Luc
 great video
 I wonder how much more weight you could put on the magnet ?
 may be you could run a piezoelectric

 all the best
 cat

gotoluc

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Re: Effects of Recirculating BEMF to Coil
« Reply #7 on: July 05, 2009, 03:02:08 AM »
Hi Cat,

thanks for posting your suggestion ;)

What I'm thinking of making is an electric motor using this principal but this can be applied to many other things.

The point that I'm trying to demonstrate here is this BEMF, Inductive Collapsing Field, Flyback Voltage or what ever you want to call it! has many more times the power to react with a magnet then the energy it takes to create it.

To me, that is amazing enough!... it is real and right in front of us :o

Lets use it!

Luc

poynt99

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Re: Effects of Recirculating BEMF to Coil
« Reply #8 on: July 05, 2009, 04:45:57 AM »
Hi .99 and everyone,

@.99, the test you have suggested have been done before I started this topic. I have been testing this for the past 7 days. I do appreciate your input and have made a new video to which I dedicated a large part to demonstrate to you by using a resistive load that the current does indeed drop slightly when the Inductive collapsing field is recirculated back into the coil.

To everyone else, I am not getting much feedback from the rest of you. Is there something that I'm missing or misunderstanding here. Please be honest and share your thoughts :)

New video: http://www.youtube.com/watch?v=_WW8z36n6z8

Luc

Hi Luc.

Thanks for doing the second test. You work quickly my friend :)

I never said I didn't believe that the current dropped with the diode in-circuit, but I was trying to see if the magnet itself had anything to do with it. It does not.

I'm happy to report that I was able to confirm almost all your findings, and I will post my results in the next hour or so.

Regards,
.99

gotoluc

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Re: Effects of Recirculating BEMF to Coil
« Reply #9 on: July 05, 2009, 05:55:00 AM »
Hi .99,

sounds interesting :)

Looking forward to your test results.

Luc

poynt99

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Re: Effects of Recirculating BEMF to Coil
« Reply #10 on: July 05, 2009, 06:36:34 AM »
Luc.

In my tests I've confirmed all your findings, except the magnet elevation, but since the magnetic field in a coil is proportional to the current through that coil, I think it's safe to say that is covered as well.

What you've built is essentially a DC-DC converter. You've taken a high voltage low current source and converted it to low voltage / high current in a load. In this case the load and conversion element are one in the same, the coil. The diode completes the appropriate circuit path that allows the conversion to actually take place.

Some numbers I obtained from my tests:

                         Ave VS    Ave IS    Ave WS    Ave VC    Ave IC    Ave WC
Without Diode:     170V       15.5mA   2.635W    157mV     15.5mA   2.43mW
With Diode:         170V       10.6mA   1.802W    2.932V     285mA    0.836W

Where:
VS = Supply Voltage
IS = Supply Current
WS = Supply Power
VC = Coil Voltage
IC = Coil Current
WC = Coil Power
(these are averaged values)

Indeed the current from the supply decreases with the diode in-circuit, but the output power from the coil never exceeds the input from the source.

Notice the huge increase in coil current with the diode in-circuit compared with it out of circuit? This explains the force it has on your neo magnet. With coils, it's all about current. A substantial amount of power has been transferred to the coil with the diode present (about 46% of the input), as opposed to nearly none without the diode.

Are there any gains in power or energy? No, in fact there is quite a substantial loss due to the DC resistance of the coil and connecting wires.

I hope this explains all that is happening with your experiment, but I'd be happy to expand on or run tests on any aspect if you want. Scope shots are also available if you wish.

Regards,
.99

gotoluc

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Re: Effects of Recirculating BEMF to Coil
« Reply #11 on: July 05, 2009, 05:56:28 PM »
Hi .99,

thank you for your test report ;) ... and to think you did all these tests without pictures or a video ;D

I do understand your point and I think you know that I was not claiming extra energy coming out of the coil compared to what is going in! that is just not possible using this simple circuit.

I am suggesting to do something else and I think many of the members at another Forum are seeing that possibility and it has lit a spark.

From my testing I also see a problem using an electronic component as a switch as it is truly not disconnecting both sides like a mechanical switch and in the end I don't think it will give the full desired effect I am thinking of, this is why I took the time to build the mechanical switch. I must say I am very please with its results other then the limit of voltage I can send through those tiny reeds.

Thank you once again for your report.

@everyone else, looking forward in seeing what your test show and ideas how to best use this effect.

Luc

wattsup

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Re: Effects of Recirculating BEMF to Coil
« Reply #12 on: July 05, 2009, 06:07:32 PM »
@gotoluc

Yes good work as usual.

With both the first and second videos, I think you have also demonstrated in this how Thanes magnets are reacting when his coil is shorted. There is an indirect parallel here with that magnet rebound effect.

I would suspect that if and when Thane puts his scope on a shorted coil while in the acceleration mode, we will see a similar waveform.

Also, thanks for making a conscious effort in reducing you use of the term BEMF. lol

I have dome some testing using  a solenoid coil taken from a cuttler-hammer breaker switch. I will try and finally work out a standard video method and make a youtube video. I am curious to know if you have tried with that big bugger of a neo magnet, when returning flyback, if you put another magnet one the coil windings, how will it affect the neo  movement. I have seen greater movement when adding one and even two magnets on the coils side. But I guess approaching any other magnets to that neo is an exercise in major havoc.

You may also try this with a small neo put inside the coil and see what happens with and without magnets on the sides of the coils.

I put up two image grabs of your scope shots so people can discuss these first hand.

poynt99

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Re: Effects of Recirculating BEMF to Coil
« Reply #13 on: July 05, 2009, 06:57:06 PM »
Hi .99,

thank you for your test report ;) ... and to think you did all these tests without pictures or a video ;D

I do understand your point and I think you know that I was not claiming extra energy coming out of the coil compared to what is going in! that is just not possible using this simple circuit.

I am suggesting to do something else and I think many of the members at another Forum are seeing that possibility and it has lit a spark.

From my testing I also see a problem using an electronic component as a switch as it is truly not disconnecting both sides like a mechanical switch and in the end I don't think it will give the full desired effect I am thinking of, this is why I took the time to build the mechanical switch. I must say I am very please with its results other then the limit of voltage I can send through those tiny reeds.

Thank you once again for your report.

@everyone else, looking forward in seeing what your test show and ideas how to best use this effect.

Luc

Luc,

A DC-DC down converter is handy when you need to be able to vary your output voltage between the ranges of your supply and almost 0V. You do this of course by changing the pulse width. 100% will yield your full 170V, and 0% will yield 0V output. This is indeed what you've built. Try increasing the pulse width and watch your magnet rise even further. It should do this continuously until either your supply gives out due to current limitations, or your coil burns up.

As a test, connect your coil directly to your variable DC power supply and begin at 0V. Increase the voltage until the magnet levitates to the same height you had with the PWM supply you built, and I am sure you will find that the current and voltage from the DC supply is very close to the numbers I gave above, i.e. ~3VDC @ ~300mADC.

The only advantage gained from a switching power supply (i.e. the PWM supply you have built with your 555, switch and coil) and a linear variable DC power is efficiency, IF you need to vary the supply voltage. If for example you only needed a fixed 3V @ 300mA supply, it would be more efficient and practical to design a linear supply tailored to the application.

I am not sure what else you will want to do with your circuit, but if you want an efficient way of varying the strength of the magnetic field from your coil, then you have accomplished that. Linear supplies become inefficient when you turn the voltage quite low and draw high current, but at full voltage they are just as efficient as a switching power supply, or at least very close.

I've attached two scope shots matched to the shots wattsup posted, as it seems you have doubts that I did any testing. It's the best I can do with the time I have available, but I can assure you that the information is accurate. The yellow trace (coil voltage) scale is the far left, while the green trace (gate voltage) scale is to the right (-2V to 30V).

I encourage you to perform the measurements I did in addition to the DC power supply test. Measuring the coil voltage and current should be straight forward for you, and you will see that indeed you've converted 170V to about 3V or so, and 10mA to about 300mA or so.

Regards,
.99

gotoluc

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Re: Effects of Recirculating BEMF to Coil
« Reply #14 on: July 05, 2009, 09:21:02 PM »
@gotoluc

Yes good work as usual.

With both the first and second videos, I think you have also demonstrated in this how Thanes magnets are reacting when his coil is shorted. There is an indirect parallel here with that magnet rebound effect.

I would suspect that if and when Thane puts his scope on a shorted coil while in the acceleration mode, we will see a similar waveform.

Also, thanks for making a conscious effort in reducing you use of the term BEMF. lol

I have dome some testing using  a solenoid coil taken from a cuttler-hammer breaker switch. I will try and finally work out a standard video method and make a youtube video. I am curious to know if you have tried with that big bugger of a neo magnet, when returning flyback, if you put another magnet one the coil windings, how will it affect the neo  movement. I have seen greater movement when adding one and even two magnets on the coils side. But I guess approaching any other magnets to that neo is an exercise in major havoc.

You may also try this with a small neo put inside the coil and see what happens with and without magnets on the sides of the coils.

I put up two image grabs of your scope shots so people can discuss these first hand.

Hi wattsup,

thanks for dropping in and adding your positive comments ;)

I think you're right about it resembling the effect that Thane has found and developed over the past years.

Thanks for taking the time to capture and post the scope shots ;)

Two people came to mind when I found this effect, Richard Willis of Magnacoaster Motor and Bob Teal.

They both used mechanical switches and timing is very important. I think it maybe the best route to take from seeing how my mechanical switch is working out.

I'll play around with small magnets on the coil sides to see if something new comes from it. However I do believe that a precise mechanical timing multiple switching is needed to also get the magnet flux kickback energy into play.

Looking forward to your findings.

Thanks for sharing

Luc