PopularFX
Home Help Search Login Register
Welcome,Guest. Please login or register.
2017-12-13, 09:15:25
News: A feature is available which provides a place all members can chat, either publicly or privately.
There is also a "Shout" feature on each page. Only available to members.

Pages: [1] 2 3 4 5 6
Author Topic: Magnetic CARA - Proof of Concept  (Read 24289 times)

Group: Moderator
Hero Member
*****

Posts: 1681


Buy me a cigar
Dear All.

This thread will be dedicated to a device that Verpies has been thinking about for a little while now.

Charge Attract Recover Abscond

The device, from what I gather, is based around a pair of Ferrite pot cores with no air gap that are separated mechanically by around 1 mm. I will now hand over to Verpies to provide a fuller explanation of the MO.

I have attached a simple drawing of my interpretation of the mechanics, Verpies perhaps you could correct any visible flaws to the design ?

Cheers Grum.


---------------------------
Nanny state ? Left at the gate !! :)
   

Hero Member
*****

Posts: 1219
PTFE rod would be a good choice.
The sliding fit should be pretty loose in order to avoid friction.
The spring should be low mass and it would have two functions:
- the obvious one: providing the axial separation of the pot core halves
- providing the radial centering of the upper core half over the PTFE rod, so ideally the upper core does not even touch the rod (avoiding the sliding in the "sliding fit").

Thus, the most engineering effort should be put into the mounting point where the top of the spring attaches to the PTFE rod, so it can be adjusted axially and radially there, with at least 0.1mm precision.  The bottom end of the spring can be attached to the upper pot core half with a strong epoxy.
Also, the bobbin, with the solenoidal coil in it, somehow should be firmly attached to the lower half of the pot core, but in such a way that it goes inside the upper half of the pot core but without touching it.  At the same time the bobbin should be removable because we will be rewinding it several times ...or replacing multiple prewound bobbins.

I will write about the magnetic MO and the electronic part in detail later.
Summary for newcomers: We will be using this setup to test whether the magnetic energy recovered from the coil is diminished by the kinetic energy gained by the accelerated upper pot core half, that the coil has attracted towards itself.  These measurements will be done on pulse by pulse basis using the circuit shown in the block diagram below.  No self-runner is expected in this version.
An analysis of a similar scenario can be read here.


P.S.
Grum, if you want to wind the bobbins before I wake up, use a thin enameled copper wire and wind one winding with even number of layers until the bobbin is full.
« Last Edit: 2015-02-01, 15:12:12 by verpies »
   

Group: Moderator
Hero Member
*****

Posts: 1681


Buy me a cigar
Dear Verpies.

Coils before breakfast ? I don't think so !!  :)

I have on stock, all in SWG,  22. 24 and 32 ECW.  Your choice ?

I am looking forward to the next instalment !!

Cheers Grum.



---------------------------
Nanny state ? Left at the gate !! :)
   

Hero Member
*****

Posts: 1219
Start with 24 just because it is in the middle of the range.

From the point of the L/R time constant, thinner wire is better because it allows for more turns and the inductance (L) increases with the square of the number of turns but resistance (R) increases linearly with the number of turns, so more turns yield a better L/R ratio because a parabola (square) grows quicker than a line.

But more turns also means more parasitic inter-winding capacitance and we just don't want to deal with that "parasite" now ...and that's I why I did not choose 32 SWG.
« Last Edit: 2015-01-22, 22:10:38 by verpies »
   

Hero Member
*****

Posts: 1219
Agreed so more turns means higher Q.  But this is only for a certain wire diameter in which more turns occupy more space.  If you have a coil former that determines the winding area and you fill it with wire (i.e. more turns means finer wire gauge) then R also goes as the square of number of turns, and Q remains the same.
I agree
« Last Edit: 2015-02-12, 12:19:36 by verpies »
   
Group: Elite
Hero Member
******

Posts: 3036
It's turtles all the way down
Verpies

I took the liberty of adding labels to the vertical time marks on your timing diagram, t0, t1, t2, t3, t4.

Now from the variable inductors point of view, what is the difference between opening switch one and closing switch two (t1 thru t3 sequence), or just eliminating switch two and leaving the coil connected to the power supply via switch one for the t1 through t3 time period, thus not needing switch 2?

Since the current continues to circulate through the inductor and in the same direction in either approach, switch 2 may not be needed.

If, for some reason you deem it is absolutely required, which has not been explained or I missed the explanation, the second approach would be less lossy. (limited by only the wire resistance of the variable inductor).

If switch 2 is absolutely required, perhaps an FET can be used for switch 2 provided a blocking diode is used to prevent conduction through the body diode (lossy approach).

Perhaps a full review of the intent of the circuit would be helpful, unless it has already been done and I missed it, in which case kindly point me to it. Then I can be more diligent in designing a drive circuit.

edit: is this the full explanation?
Quote
I will write about the magnetic MO and the electronic part in detail later.
Summary for newcomers: We will be using this setup to test whether the magnetic energy recovered from the coil is diminished by the kinetic energy gained by the accelerated upper pot core half, that the coil has attracted towards itself.  These measurements will be done on pulse by pulse basis using the circuit shown in the block diagram below.  No self-runner is expected in this version.

Other possibilities would be to mount the pot core halves on a "U" shaped piece of spring steel, at the top of the "U", thus eliminating frictional and sliding problems, additionally it would have a high "Q" like a tuning fork. There are many possible approaches to a variable inductor design.

regards, ION


---------------------------
Just because it has a patent application or is patented does not always mean it really works.
   

Group: Moderator
Hero Member
*****

Posts: 1681


Buy me a cigar

Other possibilities would be to mount the pot core halves on a "U" shaped piece of spring steel, at the top of the "U", thus eliminating frictional and sliding problems, additionally it would have a high "Q" like a tuning fork. There are many possible approaches to a variable inductor design.

regards, ION

Dear ION.

Verpies made the very same observation, a tuning fork. My concern was that the open ends would put the cores in a small arc, so that one edge would meet before the other. Having a central shaft and the core acting as a bearing should ensure an almost perfect closure of the two halves. However, if the closure of one edge before the other is not an issue then a tuning fork design would be a lot simpler to make.  O0

Cheers Grum.


---------------------------
Nanny state ? Left at the gate !! :)
   

Hero Member
*****

Posts: 1219
Now from the variable inductors point of view, what is the difference between opening switch one and closing switch two (t1 thru t3 sequence), or just eliminating switch two and leaving the coil connected to the power supply via switch one for the t1 through t3 time period, thus not needing switch 2?
Since the current continues to circulate through the inductor and in the same direction in either approach, switch 2 may not be needed.
If, for some reason you deem it is absolutely required, which has not been explained or I missed the explanation, the second approach would be less lossy. (limited by only the wire resistance of the variable inductor).
ION, you are correct that the S2 switch might not be necessary for the efficiency of the device but I need it in order to investigate pt.4 in this scenario.
This is because this is a research project whose goal is obtaining the maximum transparency of the phenomena taking place.  Without S2 I cannot isolate and measure the decrease of circulating current in L1 as the movable core is attracted closer to it and as the inductance increases.

Other possibilities would be to mount the pot core halves on a "U" shaped piece of spring steel, at the top of the "U", thus eliminating frictional and sliding problems, additionally it would have a high "Q" like a tuning fork. There are many possible approaches to a variable inductor design.
Perhaps, but the force to bend the "tuning fork" would be quite large and the core surfaces might not mate flatly.  It is an idea worth trying, though.
« Last Edit: 2015-02-01, 22:53:25 by verpies »
   

Hero Member
*****

Posts: 1219
edit: is this the full explanation?
No.
As you already know. An inductor can be charged with current which represents energy ½Li2 and later this energy can be recovered (e.g. into a capacitor) with good efficiency.

Before this energy is recovered, the inductor can perform mechanical work (e.g. attracting some soft ferrite).  As the ferrite gets attracted, its domains become polarized and pt.4 happens.
This polarization is responsible for the mechanical attraction and it also represents magnetic energy stored inside the ferrite, which can be recovered later in the form of electromagnetic energy, when the coil is discharged into C1.

The purpose of this project is to investigate the energy balance between Charging the inductor, Attracting the ferrite, discharging the inductor and Recovering the magnetic energy (including the ferrite polarization energy) and Absconding with the mechanical kinetic energy of the attracted ferrite.
Hence the acronym C.A.R.A.

The experiments of the last century clearly indicate that up to 100% of the electromagnetic energy can be recovered from the ferrite...although I think that 90% would be an excellent result considering this analysis.
However there is no data on the influence of mechanical energy gained by a soft ferrite on the electromagnetic energy recovered.

Note, that the magnetization energy of hard ferrites (magnets) cannot be recovered like that after attraction, yet most pulse motors use hard magnets as the working elements (except Orbo, etc...)

Unlike many other experiments, the energy balances in this one are easily measured by considering the voltages across C1 and C2 before and after 1 pulse, according to E=½CV2

Any questions?
   
Group: Elite
Hero Member
******

Posts: 3036
It's turtles all the way down
from Grum
Quote
Verpies made the very same observation, a tuning fork. My concern was that the open ends would put the cores in a small arc, so that one edge would meet before the other. Having a central shaft and the core acting as a bearing should ensure an almost perfect closure of the two halves. However, if the closure of one edge before the other is not an issue then a tuning fork design would be a lot simpler to make.  Afro

From verpies
Quote
Perhaps, but the force to bend the "tuning fork" would be quite large and the core surfaces might not mate flatly.  It is an idea worth trying, though.
Posted on: 2015-02-01, 22:09:47
Posted by: Grumage

I was thinking of a home made tunung fork with rather long tines for a very near parallel action.

Alternately, 2 pieces of spring steel, separated by steel blocks, ferrites pot cores glued at the center.

The best approach would allow fine adjustment of the gap and the spring tension, such a device can also be easily fabricated.


---------------------------
Just because it has a patent application or is patented does not always mean it really works.
   

Group: Moderator
Hero Member
*****

Posts: 1681


Buy me a cigar
Dear Verpies.

I downloaded a simple app for my iPad and struck the pot core half with a sharp implement.

I am getting a ringing response with 10 KHz being the centre. Are we also looking at perhaps driving at this frequency, the cores material resonance?

Cheers Grum.


---------------------------
Nanny state ? Left at the gate !! :)
   

Hero Member
*****

Posts: 1219
I am getting a ringing response with 10 KHz being the centre. Are we also looking at perhaps driving at this frequency, the cores material resonance?
Nope, at this stage NAR is not the goal nor are acoustic standing waves.
At this stage of experiment we will be analyzing single pulses at first.  I don't expect the speed of the movable core half to be much more then pistons in your reciprocating ICE engines and the range of movement will be 1mm-2mm.  That is why I liked your weak spring suspension design.

Later we can upgrade the experiment to acoustic speeds, if the results of this stage look promising.  Small steps.
   

Group: Moderator
Hero Member
*****

Posts: 1681


Buy me a cigar
Dear Verpies.

Ok, baby steps. My manual coil winder has been found and is warming up nicely in the kitchen. I DO love my wife !!  :)  PTFE / Teflon rod should be here any day now, I had to get 6mm dia, 5.5 mm not made so a little Lathe turning will be necessary to get a good free sliding fit.

Will it matter what material the conical flat spring is made from ? Brass or steel ?

Cheers Grum.


---------------------------
Nanny state ? Left at the gate !! :)
   

Hero Member
*****

Posts: 1219
Ok, baby steps. My manual coil winder has been found and is warming up nicely in the kitchen. I DO love my wife !!  :)
I know :)

Will it matter what material the conical flat spring is made from ? Brass or steel ?
Very little difference, but brass will be better, of course.
   
Hero Member
*****

Posts: 1825


Buy me some coffee
Hey guy's.

I would like to join this little venture,as i have been waiting for it to come about after chatting with verpies about it.
I do have a pair of pot core halves,and a few bobins to go with it. Only problem is that it is only 25mm OD,so quite small-->but all that is available through altronics-the guys i get all my gear through.

From my understanding,the bottom half would have to be fixed to a steady base,and the top half of the pot core able to move freely vertically,with a distance of about 1-2mm from the bottom half. This is to be an adjustable gap?,and an adjustable spring tension?.

Edit: to add a bit,the bobbins are a loose fit around the center spigot of the pot core halves,and with a couple winds of insulation tape around the bottom half of the spigot,the top half of the core should miss the bobbin.

Also in regards to the spring-->would a flat 316 S/S leaf spring type be ok to use?.

Below is a pic of the two pot core halves.
   

Hero Member
*****

Posts: 1219
From my understanding,the bottom half would have to be fixed to a steady base,and the top half of the pot core able to move freely vertically,with a distance of about 1-2mm from the bottom half. This is to be an adjustable gap?,and an adjustable spring tension?.
The spring tension should be barely enough to support the weight of one core half...so pretty weak.
The air gap is not critical.

Edit: to add a bit,the bobbins are a loose fit around the center spigot of the pot core halves,
Just the top half needs to be loose.

...the top half of the core should miss the bobbin.
Yes, the top half should not touch the bobbin at all.  If it does, then it will disturb KE measurements.

Also in regards to the spring-->would a flat 316 S/S leaf spring type be ok to use?.
If you can make the core surfaces mate evenly
   
Hero Member
*****

Posts: 1825


Buy me some coffee
The air gap is not critical.
Just the top half needs to be loose.
Yes, the top half should not touch the bobbin at all.  If it does, then it will disturb KE measurements.
If you can make the core surfaces mate evenly
Quote
The spring tension should be barely enough to support the weight of one core half...so pretty weak.
How will this weak spring go returning the pot core half to resting position in the higher frequencies in time?

I will start with .2mm wire,as my former and core's are small.
Also-what are we using for a switching device-circuit etc.? My SG is cabable of 1 shot pulses,up to 1 minute apart-any wave form, duration and amplitude up to 18 volts,150mA
   

Hero Member
*****

Posts: 1219
How will this weak spring go returning the pot core half to resting position in the higher frequencies in time?
Slowly.  This experiment is done on single pulse-by-pulse basis.  There is no quick succession of pulses as in other devices...thus there is no repetition frequency.

I see it like this:
1) First the capacitor C1 gets charged to +V1 by momentarily pressing S0 and C2 gets discharged by shorting it momentarily.
2) Then S1 closes and L1 becomes energized (the pot core starts getting attracted)
3) Next, S2 closes and S1 opens which traps the energy in L1 (I call it the "hold phase", during which the pot core continues getting attracted)
4) Finally, S2 opens and the energy stored in L1 (and in the aligned domains of the potcore) is recovered to C2.
5) The voltage across C2 and C1 is compared to obtain the Out/In EM energy ratio.
6) The kinetic energy of the core is estimated somehow

The entire sequence of events listed above must happen before the core halves slam into each other.



Of course, MOSFETs should play the roles of S1 and S2.  They should be driven by rectangular pulses of variable width.
Before ION and I design a good method of driving S1 and S2 from a common voltage level, the S2 can be entirely omitted for preliminary experiments.

WARNING: I exchanged the labels C1 and C2 on the diagram above, compared to the previous diagrams, in order to better follow the sequence of events.  
Also, I added the momentary manual switch S0 for precharging C1 and supplying the entire sequence only from C1, for precise input energy measurement.
   

Group: Moderator
Hero Member
*****

Posts: 1681


Buy me a cigar
Dear all.

My PTFE/Teflon rod arrived today looking more like a white Banana than something that will go into the Lathe chuck !!
Suppliers are resending a replacement.

Cheers Grum.


---------------------------
Nanny state ? Left at the gate !! :)
   

Hero Member
*****

Posts: 1219
Not thick enough to turn down the curvature?
   

Group: Moderator
Hero Member
*****

Posts: 1681


Buy me a cigar
Not thick enough to turn down the curvature?

Sadly no.

I ordered 6 mm dia, the working diameter is 5.5 mm, no room at all for the error that arrived ! Perhaps Banana wasn't the best description, full of " Waterloo sunset's " !!......http://www.youtube.com/watch?v=N_MqfF0WBsU

Sorry, you can blame an upbringing of The Goons and Monty Python, I had great parents!!

Cheers Grum.


---------------------------
Nanny state ? Left at the gate !! :)
   

Hero Member
*****

Posts: 1179

First testrun with pot core halfs just on top of each other.

Using 9x 1nF Wima MKP 4 which i use parallel (not sure where the 10th is) as C2, a 470nF Wima MKP 10 for C1, a SCS106AGC diode and a dale 0.1 Ohm induction free csr.
The pot core has 3 coils presently, one 360mH which i now used, one 15mH and one 11mH when all clamped up.


Monitoring the csr with the yellow probe  (no activity), and the voltage across C2 with the blue probe, see screenshot.
FG was in single pulse mode.

Video here: https://www.youtube.com/watch?v=egSBMe9WE4Y&feature=youtu.be


Regards Itsu


   

Hero Member
*****

Posts: 1219
Monitoring the csr with the yellow probe  (no activity), and the voltage across C2 with the blue probe, see screenshot.
FG was in single pulse mode.
Video here: https://www.youtube.com/watch?v=egSBMe9WE4Y&feature=youtu.be
There is something wrong.  You must have some activity across R1 and a voltage pulse at point D.
Is the ground of C1 connected to the Source of Q1 ?


« Last Edit: 2015-02-06, 02:50:07 by verpies »
   

Hero Member
*****

Posts: 1179
There is something wrong.  You must have some activity across R1 and a voltage pulse at point D.
Is the ground of C1 connected to the Source of Q1 ?




I will add another probe to monitor point D tonight,
yes C1 is grounded to the same PS return point as the source of Q1

Regards Itsu
   

Hero Member
*****

Posts: 1219
...and D1 and Q1 should prevent C2 from getting charged when S0 is pressed.
Is D1 ok and polarized correctly?
   
Pages: [1] 2 3 4 5 6
« previous next »


 

Home Help Search Login Register
Theme © PopularFX | Based on PFX Ideas! | Scripts from iScript4u 2017-12-13, 09:15:25