Confirming the Delayed Lenz Effect

[MileHigh]

A suggestion for controlling the pulse timing for a pulse motor:

Let's suppose you have a pulse motor with two rotor magnets 180 degrees apart and only a single drive coil.  You can use the the side of the motor that is opposite the drive coil to trigger the timing.

All that you need is two Hall sensor and associated circuits, one to initiate the pulse and the other to end the pulse.  Let's call them the start and stop angles.  So you can move the Hall sensors around and have complete and absolute control over the start and stop angles for the pulse.

All that you need to do is connect your Hall sensor signals to a set-reset flip-flop.   Then the output of the flip-flop will fire the transistor that energizes the coil.

This is really not rocket science and judging by the discussion around here lately the skills are available to do this.

Finally, you simply can't do something like this and fly blind.  I have already discussed how you could put a sensor coil 180 degrees away from the drive coil and connect that up to one of your scope channels so that you have a timing reference to work with.  That way as you change the angle of your start and stop points for the energizing of the coil, you will be able to see that in real time on your scope.  You leave one scope channel on the sensor coil and you move the other scope channel around to look at the logic level that fires the drive coil, or the voltage across the drive coil, or the current through the drive coil, etc.

Think about this:  Just hold the non-turning rotor in your hand and switch on the drive coil with pure DC.  Feel the torque on the rotor as you move a rotor magnet past the drive coil.  We are taking as low tech as possible here, your measuring instrument is your hand!  At what angle do you feel the most torque on the rotor?  That's your "sweet spot" angle.  Armed with that knowledge, you try to make the start and stop Hall sensor angles to be before and after the sweet spot angle.  The closer the start and stop angles are to each other, the shorter time the drive coil is energized.  Just play around and find the right start and stop angle to give you a "satisfying" rotor RPM and power consumption.

That's the key for getting the most efficient pulse motor when you define efficiency as highest RPM for least power input.   At least that's what it looks like to me.  You can do all of this with absolute and complete control with two lousy Hall sensors and a twenty-five-cent SR flip-flop.

MileHigh

[Magluvin]

Like i said it depends on what you want, I want as short as possible "on times" so a snubber is counter productive to me. you can't start the next pulse until the first event is over. Snubbers are for switching relays or loads like Regular DC PM motors and stuff in my opinion. Each to their own. The point is I gave an "opinion" and then you made out I was wrong which was impossible anyway because it was my "opinion", I did state that. I'll show a test as well then. I've got a fixed "on" time and adjustable timing so to leave everything the same and make the snubber change will show any effect at all. I might need to turn it off to make the change so I'll probably use a pull starter to get back up to speed quickly for the video. My motor doesn't like to run below 1000 rpm without changing the pulse width or the timing. I'll keep discharging my coils to a higher voltage be it a capacitor or a battery. Even using a 12 volt globe as a load like a snubber slows the motor and no change I make can make it perform like when the coil is discharged to a higher voltage. We need to work with what actually happens in our own setups. Anyway I'll make another clip, I don't want to be misunderstood because of my way of explaining things or whatever reason.

When the coil discharges current doesn't flow through it current flows "from" it, If current flowed through it then a current could be scoped into the coil from the rail when the switch is "off", my intuition tells me that when the switch is "off" no current enters the rail end of the coil because the switch is off, it is the halting of the current that causes the
field to collapse. "Through" and "From" are quite different. Also if current was flowing through the coil it would create a magnetic field, I don't think this is the case. After the switch closes the magnetic field only gets less I think.

How would a person detect and measure a spike in the magnetic field strength, density or size as a result of the collapsing field ?

Cheers

"Like i said it depends on what you want, I want as short as possible "on times" so a snubber is counter productive to me. you can't start the next pulse until the first event is over."

Well then use a shorter pulse and get the rest through the snubber. That is if your pulse is meant to provide motive force to the rotor.

"Snubbers are for switching relays or loads like Regular DC PM motors and stuff in my opinion."

Actually some relays that are meant for very fast action wont use the snubber. But general purpose would. I have seen resistors used. They require a bit more to run, but the resistor limits the freewheel current enough for the contacts to open in a timely fashion and absorb the emf produced
Like I said before, we can use the collapse to charge a cap, through a diode, or just keep the coil active longer with the snubber and the collapse energy is stored in the rotor by pushing longer than the input.

"Each to their own. The point is I gave an "opinion" and then you made out I was wrong which was impossible anyway because it was my "opinion", I did state that. I'll show a test as well then."

Well your opinion was based on facts from your experiments and I was just pointing out that possibly your experiments needed further tinkering to see otherwise.

Didnt mean for it to come out badly.

"I've got a fixed "on" time and adjustable timing so to leave everything the same and make the snubber change will show any effect at all."

What I had found was that I could shorten the pulse if I added the diode across the coil and run the same speeds. Are you running repel or attraction?



"When the coil discharges current doesn't flow through it current flows "from" it, If current flowed through it then a current could be scoped into the coil from the rail when the switch is "off", my intuition tells me that when the switch is "off" no current enters the rail end of the coil because the switch is off, it is the halting of the current that causes the
field to collapse."

When I say 'through', Im talking about the wire of the coil.  Like if you wound the coil say 4 layers leaving the 2 leads extended out, then add another 4 layers with those leads accessible also. Now there should be 2 wires coming out of the middle of the coil, between the 2 layers. Connect those to leads to a current measuring shunt resistor. Now the coil is very similar to an 8 layer coil with a little added resistance. If you apply a scope across the resistor and operate the coil, there will be voltage across that resistor and it is an indicator of current flowing through the coil. No? Just explaining my 'through'.


"When the coil discharges current doesn't flow through it current flows "from" it, If current flowed through it then a current could be scoped into the coil from the rail when the switch is "off", my intuition tells me that when the switch is "off" no current enters the rail end of the coil because the switch is off, it is the halting of the current that causes the
field to collapse. "Through" and "From" are quite different. Also if current was flowing through the coil it would create a magnetic field, I don't think this is the case. After the switch closes the magnetic field only gets less I think."

Well if there is no path for the 'current' to flow when the switch is off, the collapse is near instantaneous because relatively no current can flow 'through' the coil because it has no where to go. The speed of that collapse induces very high potential at the ends of the coil . Like a neon transformer will spark to your finger just from one end of the secondary with the other end open. Electrons are being compressed and decompressed from end to end of the coil(open secondary) 'wire'. This is current flow back and forth through the open secondary, how ever small it is without anywhere else to go till we load it, is current flow.The AV plug charging a cap from an open end of a secondary is a good example.
This can be seen in a sim easily enough where the snubber keeps current flowing in the coil, in the same direction as the input after switch off, and the collapse is slower because of Lenz. Less Lenz, faster collapse. When the coil is loaded during collapse, much more current flows during the collapse, thus lenz effect against the collapse and slowing it down. And the reason the collapse produces current is that the field lines are 'cutting' the windings. General Generator action.

Here is an example. If we have a transformer that we only pulse the primary with dc, we will see an output to a load that coincides with the input. But if we put a diode on one lead of the secondary in series with the load so that current cant flow like the diode less example, the secondary wont show output till the primary pulse has stopped. Then the secondary will show output to the load, and it happens because of the collapse from the primary pulse, not the build.

Here is a strange one that some dont know. A simple pulse motor with a diode to a cap from the coil to collect collapse. Then try the diode in either direction. If the input to the motor is say 5v, how did we get more to the capture cap, with the diode either way? Its not from generator action, thats for sure. And its not from the input. 

One way, the diode will charge the cap from the input while charging the coil from the input pulse. The diode in other direction will only collect the collapse. But both ways will provide high voltage to the cap. In the direction where the cap charges from the pulse while powering the coil, there is loss there in the charging of the cap directly from the input while the switch is on, but after that the cap is higher and the rest comes from collapse.

How can the collapse charge in both directions? If the field collapses without a load(diode and cap) on the coil, the field goes into a complete reversal, peaks in the other direction and then that second collapse is sent through the diode to the cap, because that second collapse in the opposite direction does produce the polarity for the diode to conduct.

The reason that the field of the open coil can go into complete reversal is the fact that the coil does have a tiny capacitance, along with its inductance, it oscillates. Very high freq oscillation, but still oscillation.

Im not here to mess with you.  Just help.

Mags

[Farmhand]

Well can you measure current into the coil "rail end" during the discharge ? OR is the energy returning to the supply which is connected to the coil at the rail ?
If the coil discharges through itself then where does the energy go ? I think the snubber returns the inductive energy to the supply. We ought to be able to measure current into the coil during the coil collapse if what you say is true, lets do it.

Just making the pulse shorter does not work to keep the same force on the rotor. My rotor is both attracted to the core and repulsed, it can run both ways but really it's the same, the coil negates the attraction or it adds torque itself same thing different magnitude.

Anyway endless argument is pointless, I disagree on several points. But I'm not here to argue either.

I wasn't asking for help, I'm fine.

Cheers

[MileHigh]

Farmhand:

If a coil self-resonates the energy is dissipated in the wire of the coil.  If you put a reverse-biased diode across a coil, a.k.a.; a "snubber," when the transistor switches off all of the energy is dissipated in the diode and the wire of the coil.  If there is still a bit of "push" left in the coil to help the rotor along like Magluvin does, then some of the coil energy goes into the push.

The true bifilar trick that we discussed a while back is one way to pump the coil energy back into the source battery.

I encourage you guys to keep exploring.  For example, you get your pulse motor running, so what next?  How about measuring your RPM per input watt and seeing how that changes as the speed increases.  In theory it should start going down as the rotor pushes harder against the air friction.  Or how about hooking up your pulse motors to a generator so you get some useful output from it.  How about trying to come up with some sort of metric so that you can compare different pulse motor builds.  This is very much of an apples vs. oranges game.

A tough one is to try to measure the moment of inertia of your rotor.  That's the key to figuring out the mechanical power required to keep the rotor turning at a given RPM.  Then you can compare the average electrical input power to the mechanical power required to spin the rotor.  I know I am shooting blanks but what the hell.  This is the kind of stuff that I did in junior college in the 1970s using strip chart recorders.

MileHigh

[Farmhand]

Sorry about another reply.  It's an interesting subject but a bit off topic here. Anyway I had arguments with "trained" folks on these forums about how it is said that coils work on current not voltage. In my opinion it's energy not necessarily either current or voltage but the effect of a certain voltage on a certain resistance will result in a certain current.

I argued that if a coil is switched to ground like with a low side switch then with the closed loop current theory current must flow immediately to ground and through the battery at the same magnitude it is leaving the battery. But I was told that there is a delay because of the inductance, I was told that for a small period as the magnetic field is building there is no current leaving the coil but there is current entering the coil. And so I figure when the coil discharges the same thing happens in reverse.

My original argument was that "electron current may occur" or "measured current" but the charge would be stripped from the current to build the field.

So that we would have a current of "electrons bumping each other" and a current which is the flow of charge or charges which is independent of the electron movement but the electron movement is the "footprint" or "wake" of the charges. ie. a big boat going fast makes a big "wake" and even if the boat was invisible the wake could be seen and measured to determine the size of the invisible boat.  The energy of the charges would be related to the magnitude of the current, which is related to the potential of the applied voltage that caused it, and the resistance it faces. So the energy is in the flow of charges not the flow of electrons, flow = current.  The coil in my opinion works on the flow of charges not the flow of electrons so much although they flow together  It is complicated. But it's all just my opinion. I said at the time of the argument with the other person that I would like to test that and see that there is no flow of current from the coil negative when the magnetic field is building, which would be similar to testing to see that there is no current entering the coil during the coil field collapse.

Cheers

P.S> Going by the argument that current enters the coil while the field is building but no current leaves the coil while the field is building, it should be possible to switch a coil to ground an open the switch again before any current at all flows to ground through the switch. Is it possible ? That's the question. In that case current would leave the battery positive but none would enter the battery negative. To me it doesn't make sense. Because that is not supposed to be possible. If a diode is between the battery positive and the coil
and the coil discharges back to the coil then no current could flow to the battery negative.

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