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Author Topic: A closer look at a simulated Negative resistance coil.  (Read 58704 times)

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Now that's interesting, scope shot 2 shows lots of high frequency noise, periodically as i am testing loads of noise appears across the LC, looks like i captured it in shot 2, it's sporadic, and appears maybe ,mains born noise as i am 100 foot down the end of an extension lead at the moment.
   
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OK, that still calculates at a series loss resistance of 97 ohms so there might be something there.  The expected series R core loss against frequency should be something like the chart here, calculated from the published 3C90 data.  If the bucking plus magnetic delay is producing anything that smooth rising curve would show a negative going lump on it so perhaps that is what to look for.

Smudge

Edit.  Darn forgot the chart again.
   
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Peter,

Those latest results show the loss R in series with LC is 27 ohms.  There is little point in doing many different load R values since the COP's you get are all associated with that fixed 27 ohm internal loss.   It would be far more beneficial to stick with one load R and do different frequencies, then plot the loss R against frequency.  We are looking for an inflection in that curve to indicate an anomalous effect.  The loss R is simply the LC voltage divided by the current.

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OK can do that tomorrow, any preference on frequency sampling spacing, is 100KHz OK
and what fixed load resistance is best for me to stick with.
   
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100KHz spacing OK to start with, starting at 100KHz then see what happens as you go up to 500KHz.  100 ohms for the load.

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OK did 10KHz spacing in the end, started at 100KHZ & finished at 800KHz, as there are over 60 shots i have zipped them, i will process the data and append to this post once done.

EDIT Added spreadsheet with data
PS i now calculate LC Resistance in the spread sheet
« Last Edit: 2015-03-13, 18:44:16 by Peterae »
   
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Hi Peter,

That's an impressive set of results, well done.  I have plotted the loss R of the LC and it shows no sign of the wanted effect :'( .  It is a straight line on a log-linear plot, see image Loss R.bmp.

I guess the next step is to introduce some deliberate magnetic delay between the two coils and see what effect this has.  My suggestion for the magnetic delay is to create a magnetic delay line by winding a series of coils and connect them with capacitors, as shown in the attached images.  The first one shows a balanced delay line that would be classical but for the fact that the input and output are magnetically coupled.  The core is shown as rectangular with input and output coils at each end.  The delay region would have the end capacitors at one half the value of all the other ones.  This needs transposing to the circular core you use.  The second image shows the top and bottom winding directions with the capacitor cross connections in simplified form.  In the limit you could use single turn coils and lots of capacitors.  Start with small value capacitors, use one of your coils as an input and the other diametrically opposite as an output and see what delay you get.  With some significant delay it would then be interesting to try the bucking coil arrangement and see how it differs from those present results.

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Hi Smudge
Thanks, I'm away for a course 2 days and am revising at the moment, so not much will happen now until the weekend  O0

I did try again to see a delay between one coil and the other as the new scope does phase angle, but it was still inconclusive and did not really see a movement in phase so this next setup will be interesting if we can indeed introduce the phase delay big enough to be measured  O0

Cheers
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Hi Smudge
Got any ideas for values of cap to try, shall i do single wire turns or a few turns per winding and how many windings, we might as well try for a significant delay to make it obvious, i am trying to plan the work i will do over the weekend, easier for me if you put a proposal to me as opposed to me trying random values that may not work out.

PS maybe you have a ball park inductance for each coil with a cap value that can be calculated for an expected delay result.
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Hi Smudge
Got any ideas for values of cap to try, shall i do single wire turns or a few turns per winding and how many windings, we might as well try for a significant delay to make it obvious, i am trying to plan the work i will do over the weekend, easier for me if you put a proposal to me as opposed to me trying random values that may not work out.

PS maybe you have a ball park inductance for each coil with a cap value that can be calculated for an expected delay result.
Cheers
Peter

If you aim for say 1 uS per section and you had 10 across the top and 10 across the bottom you would get a 10uS delay.  For that 1 uS you need for each section
1 turn and 0.2355 uF
2 turns and 0.0589 uF
3 turns and 0.0262 uF

Take your pick.

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Just to get everyone's brain working overtime, here is another suggestion for a different form of delay transformer.

Smudge
   

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Thanks Smudge that will save me a lot of time.

PS if you find a cheap ring core on farnell, i can order a quantity to try to build the device in your new PDF for a delay transformer.
The one with the high K ring, we could use a  ring containing pure water, pure water can have a K of 80 @ 20 Deg C, i have a RO machine for pure water, just need to find something to contain it in a ring, if a hose was used then we could make the high K ring quiet large in diameter, just join the 2 ends together and fill it with water.
« Last Edit: 2015-03-19, 22:00:29 by Peterae »
   
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While searching for an old paper of mine I discovered some more on magnetic delay which might be of interest.

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Hi Smudge,

Thanks for sending those papers you turned up. The 'lumped constant' one has the test I remembered, and it's good to see it again.

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From Peter

Quote
The one with the high K ring, we could use a  ring containing pure water, pure water can have a K of 80 @ 20 Deg C, i have a RO machine for pure water, just need to find something to contain it in a ring, if a hose was used then we could make the high K ring quiet large in diameter, just join the 2 ends together and fill it with water.

An elongated pseudo ring might work with 2 long rods of high K  ceramic material.

For a "K" in the thousands you could cast two Barium Titanate rods and fire them in a kiln. First you would mix into a slurry using water, then squeeze it in a cylinder former with a press, driving out most of the water. After ejection from the cylinder former, they would be fired in a kiln to promote crystal growth.

After firing, the rod ends would be sputtered with copper for soldering or a silver epoxy could be used. The ferrites would be slipped over the rods, after which the connecting wires with drive ferrites would be applied.

This is an abbreviated method of high voltage ceramic capacitor construction. More here:

http://www.scielo.org.ar/pdf/laar/v35n1/v35n1a05
« Last Edit: 2015-03-20, 22:56:48 by ION »


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Sounds good ION, not quiet got all the equipment to do this yet, but have the vacuum pump.
If i ever get enough time a kiln would be a great addition and also a sputtering chamber  O0
   
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Sounds good ION, not quiet got all the equipment to do this yet, but have the vacuum pump.
If i ever get enough time a kiln would be a great addition and also a sputtering chamber  O0

See if Smudge approves, I don't want to modify his original sketch if he has some reason why it might not work with rods.

Barium Titanate rods may be available commercially. Also consider that certain very high resistance ferrite rods might work as capacitors, you would only need to make the ends conductive and you might be able to dispense with many of the ring ferrites as they would be inherent in the rod design.


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Hi folks,

I believe the rod is a better structure for both the domain delay line, and any capacitance that is coupled to it.
There's something just not right about the toroid structure to me.
Consider a toroid with a single pulse coil.
The cone shaped domain wall nucleates in the center of the coil and then expands in both directions through the core. There are two domain walls expanding in opposite directions. Each domain wall as it moves away from the nucleating coil will have *the same inverted conical shape*, with the points of both cones aiming at the center of the coil. 
The divergence of these walls creates a rapidly diminishing diamond shaped region of remaining random flux on the opposite side of the toroid. But it appears to me that the two domain walls are somewhat 'solitonic', and to preserve both the energy stored in the domain wall rotation process, and the forward momentum, they will pass through each other at that point--??

Smudge has pointed out that surface waves travel at right angles to the iron, and in a toroid these begin at the coil and expand through the central and surrounding spaces. These waves could be synchronized with the magnetization wave inside the toroid, or could be at C, or could be instantaneous-- I don't know. According to the thesis from the naval student I sent a while back, on a toroid the surface waves arise from the coil surface and then travel at right angles to the toroid, until they merge on the other side.

I agree that Smudge should weigh in on the nature of the capacitive loading used.

High-resistance (low-loss) ferrites have a electrically controllable permeability. See attached patent, which I mentioned to Smudge a while back but couldn't find. So cleaning the ends of the ferrite rod, then soldering some leads to it, should allow reasonable amount of control of mu, but you would need a DC HV generator. The attached patent shows how to do this, although it doesn't show the voltages needed. Probably pretty high.

BaTi rods may not be available since their functions have been taken over by even higher k perovskites like LZT, but any of these should work. Long rods are not made, AFAIK. The attached datasheet for an electrostrictive sonar transducer rod is probably as good as it gets, but haven't found any LZT rod like this available on a 'buy one' basis. It would be an expensive way to go. I think the Cyril mentioned soaking the delay line in a liquid dielectric, and this seems a lot easier if Smudge's multiple shunted capacitor method doesn't work out.

Those Perovskite rods can be used for acoustic overunity devices as Wooten MRA, Hutchison's '5 Watt generator', Davidson's magneto- acoustic generator, plus various nonreciprocal transducer designs, plus ambient thermodielectric generators with high output, plus detectors of the Earth's diurnal gravitomagnetic fluctuations, etc. -- So, always a good thing to have around :-)

orthofield





   

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Hi Smudge
I built the delay as per your toroid diagram above 157.

I used 6 off 220nF caps with each 1 turn of thick gauge wire, so we have 5 turns each side

It appears to be very frequency dependant.
I tested at 600KHz & 500KHz , at 300KHz i was having trouble seeing a delay, i think there was one but it was impossible to measure.

At 600KHz we had 139 Degrees of shift with a time period shift of 644nS
At 500KHz we had 84 Degrees of shift with a time period shift of 464nS

EDIT just to explain the set up
My sig gen is across the Yellow scope probe and across one end inductor
My blue scope probe is across inductor at other end of the toroid
« Last Edit: 2015-03-21, 22:27:27 by Peterae »
   
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Wow, those are huge phase shifts.  Can you please try a few things.  First disconnect all the capacitors and check that the phase shift is zero and not 180 degrees (easy to get one of the coil connections the wrong way round).  That establishes the starting base line.  Then reconnect but now put a 50 ohm load onto the output (I assume your sig gen is 50 ohms, if not use the sig gen value).  An open circuit delay line will have weird phase effects at different frequencies so we need to isolate them from the true delay, and that may be why your 300KHz result was so different.  You could also try a pulse input.  I see there is a voltage attenuation which is to be expected so don't expect the pulse shape to be preserved.  You are treading new ground here with this deliberate phase or time delay within a transformer core, so may I suggest you keep reasonable notes on your experiments.

An alternative approach may be to start with all capacitors disconnected and a pulse input. Then add small value capacitors, like 10 pF and note the effect.  Continue gradually increasing the capacitor values, and the trends that occur should tell us a lot about what is going on.

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Hi Smudge
As it was disconnected after the test and reconnected for bucking mode, i cannot be sure which way i had the probes connected in the above test, to be sure in the future i have marked + & - on each winding, anyway i am doing what you suggest in your post.

So i connected the caps back up after verifying the polarity of each coil, and it is still variable dependent on the frequency, there is a frequency @ 750KHz where input is in phase with output, if i go higher in frequency the input phase leads, but if i go lower in frequency the output phase leads  :o

Anyway i will continue with your post above.
Quote
Then reconnect but now put a 50 ohm load onto the output
When you say output do you mean the sig gen output or the output coil, i will try both, and yes my signal gen is switchable 50 Ohm or high impedance and was set to high impedance during all previous tests (only just found this setting in the internal help screen), i have now switched to 50 Ohm.

Pulse mode at 10% duty 100KHz, yellow across sig gen & coil, cyan across other end inductor
Shot 93 = no 50 Ohm resistor
94=50 Ohm across sig get & coil
95=50 Ohm across load coil

EDIT just been rereading your posts above and noticed this
Quote
The delay region would have the end capacitors at one half the value of all the other ones.
So it looks like my end caps need to be half my mid caps value, as i have been using 220nF then i will try some 100nF at each end, is that right?
« Last Edit: 2015-03-22, 14:22:00 by Peterae »
   
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I silvered the ends of a number of ferrite rods of unknown material type. These were removed from old radios. The capacitance was negligible, just a few picofarads.

I have a U shaped ferrite core (normally also called a C) from some switching magnetic structure like a HV flyback core.

To my surprise with the ends (mating faces) silvered, it read 1500 pF.

For what it's worth.


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Hi Smudge, all,

I found this patent while looking for something else. It is a bit of an outlier to the present discussion, but might provoke some thought.
It talks about "magneto-electric induction" , the inverse of electro-magnetic induction, where a dielectric wire is wound around a ferrite core. Putting an electric field through the wire from a HV source creates a magnetic flux in the ferrite. The inventor, at Bell Labs, claims that the symmetry of Maxwell's equations say it makes no difference if the magnetic field in the toroid comes from a real current, or a displacement current. This seems odd to me because it implies you could use a very high impedance, high frequency source (like some Tesla coils) into a dielectric 'wire' around the core to create an oscillating magnetic field in the core. What happens when another, copper, coil is put around this, and the magnetic field is tapped for power? Does the Tesla coil experience a load proportional to the loaded coil?

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Hi Ion,

Thanks for checking out the bulk C of the different ferrite forms. It obviously can vary a lot and the more modern the material, and thus the less conductivity, the better.
 
I'd just been reading in the patent I sent about how it was hard to make measurements of dielectric constant when the materials were high-k, because the quality of the electrode contact with the material becomes a major factor... so silvering was the ideal contact method, really :-)

If you've got an LC meter you're in a perfect position to check for the effect on the mu of your ferrite U core by first measuring L of a coil around it, then 'charging' the ferrite like a capacitor through the silvered regions, and then remeasuring the L. The ferrite can be considered to be a somewhat leaky capacitor, I think, so some of the capacitor energy should even be recoverable.  As discussed in the Desguerra patent, (and another patent I haven't found again yet) there should be an effect of perhaps 10% change in mu due to electric field with your U core. As mentioned, the patent doesn't give numbers on the E-field used, but I'd guess it was pretty high, but hopefully no more than 100 V or so..if you don't see an effect with 100 V or so, I wouldn't bother going higher...

Having a transducer like this, where the ferrite mu can be varied electrically, gives us easy reactive amplification of currents without having to worry about any real impact on the voltage source. Whether this is useful just depends on how big the effect is, in a really high quality core.

Most of the experiments on this sort of thing I've seen involve core *currents* through amorphous metal strip, rather than ferrites. There, very small currents can change the mu of the material dramatically. This effect is enhanced even more when the strip is twisted. I've proposed ou designs based on reactive amplification using a twisted strip of metglas ribbon--which should have hugely nonlinear reactions to small currents-- but nobody has ever taken me up on it :-)

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Good find Ortho.  The link between electric and magnetic effects is well covered in EM theory and the inventor is quite right.  You can wind the electric circuit around the magnetic core or you can wind the magnetic circuit around an electric core.  Displacement current creates a magnetic field.  I once invented a transformer that consisted of a parallel plate capaciitor in the form of a circular disc of dielectric placed within a circular ring of ferromagnetic material.  The capacitor was in effect part of a single turn.  To get the equivalent of a step up or step down ratio the capacitor was divided into two by having separated electrodes on the flat surfaces of the dielectric.  So in effect there were two turns, each with its own capacitor, one turn being the primary and the other the secondary.  Equal capacitances gave 1:1 ratio.  Unequal capacitances gave step up or step down.  For symmetry the electrodes were concentric.  It was a transformer that primarily gave you a current ratio, not a voltage ratio.  But of course only worked at high frequencies.   Never did take a patent.  And you can get the equivalent by shifting separate capacitors along the wire so they are not then within the core, you then have a conventional 1:1 transformer with different value series capacitors in primary and secondary and that too acts like a current transformer.

Smudge
   
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