Hi kingrs,

Yes, LTSpice is amazing. It has shocked me several times so far in its accuracy. Too bad it can't predict Naudin's metglas MEG.   Make sure you get the latest update by clicked Tools -> Sync Release.  One thing I love about ltspice is FFT spectrum displays. On a graph just right click and select FFT. You'll see a window full of options. Default is usually good. Sometimes you'll want to bump up the data samples. Click OK then you'll see the FT graph. The default display is DB vs. Log.  Just left click (not right click) on the DB or KHz numbers to change this. I like linear in Cartesian display. This will give you the typical Amplitude & Phase.  Another great option is testing for component noise. I used it to accurately design a 3 stage FET amp that had less than 1nV/Rt noise. In noise mode it will tell graph the voltage noises inherent in parts. LTSpice knows about all the different types of noises from thermal noise to shot. Lots of goodies.

I added an extra 1.6Ohm resistor to the circuit in series with the input coils and it seems to make little difference to the current, which seems odd.

Actually I already placed the 1.6 R in the inductor. Just right click on the L1 or L2 and you'll see it has 1.6 ohms for the series resistance field. Same goes for L3 & L4 except it's 37 ohms.  So you don't need to add another 1.6 R.  Also you'll see all the inductors have parallel R and parallel capacitance.

The inductors are coupled with the Kx commands. I could have just did K1 L1 L2 L3 L4 0.99 for example, but I broke them up to give each coupling a unique coefficient so as to represent the MEG core since the two secondary coils are appreciably separated from the actuators.

This is going to be interesting to see the results.  I think Naudin's 100K is closer to 35K, but people are saying it varies in resistance.

BTW, I tried replacing BUZ11 with IRF540 and what a difference. The irf540's are a lot slower than buz11's so the sim is a lot faster.

Regards,
Paul Lowrance

Hi Rob,

My datasheets show the BUZ11 turns on twice as fast as the IRF540-- 30ns vs. 60ns.  Although the IRF540 turns off a lot faster-- 180ns vs. 50ns.  I'm thinking the turn on speed is very important in the MEG.

So don't discount those BUZ11's, lol.

I've been doing some FEMM simulations on the MEG. Due to the PM's the core field drastically drops at around 15 volts. I made an exact copy of the Metglas 320 core, 100 turns on actuator (MEGv21). Naudin's FEMM simulations are incorrect because he assumes the core's permeability is the same at 30KHz vs. DC. That Metglas core at 30 KHz has roughly the same permeability as FEMM's iron material. Naudin's power charts show a larger rise at around 20 to 25 volts input, which seems to agree with my FEMM simulations. Also anything after 25 volts does not help as much, which is probably why his power chart shows a huge decrease in efficiency at 30 volts.

I did sims on both Neo and ceramic magnets. The neo's will probably work well at higher input voltages and the ceramics work better at lower input voltages. This is because the neo's introduces a stronger traverse field near where the magnets and core touch. Traverse fields can hurt permeability. Ceramics might be a best first choice since they work better at lower input voltages and that's what Naudin used.

Regards,
Paul Lowrance

Hi Paul,
Thats interesting, looks like every one and his dog makes a different version on the BUZ11.
RS have discontinued them all 4 of them.
They all appear to have different properties, and I bet if you bought two of the same and tested them they would show different speeds.
Price of the part seems to vary between manufacturers and it looks like its being discontinued all over the place.

Can you post your femm files.

Did you put in the material for the Metglas core (B/H curve), I had to do this the other day for a ferrite and it was not easy?

Core should arrive tomorrow and I will post a picture of it so you can see what it looks like.
I still need to order the bits for the pulse circuit.  Are you getting a TL494 chip?
I noticed that the TL494IN is the one to go for as it works at -40c to +85c, (brrrrrr to damm thats hot!).

I need to check my scope still works and look at sorting out the interface to the PC for it.
I'm tempted to get a Stingray usb scope but the input burns out at +/- 50v and the potential offset probes cost more than the scope.


Regards

Rob

Hi Paul,
Thanks for the FEMM files.


I have a temperature probe I can attach to the core, and using the supplied chart I can work out the exact temperature from the resistance change.

Well the core has arrived, very professional bit of kit.

The ultimate core  "the AMCC-320":

(http://i100.photobucket.com/albums/m25/kingrs/DSCN4727.jpg)
(http://i100.photobucket.com/albums/m25/kingrs/DSCN4729.jpg)
(http://i100.photobucket.com/albums/m25/kingrs/DSCN4732.jpg)
(http://i100.photobucket.com/albums/m25/kingrs/DSCN4733.jpg)

Regards

Rob

Hi Paul,
Do you have any photos of your core?
You can upload to photobucket like I do for free.

Quote from: PaulLowrance

Be careful inserting the PM's as Metglas is very brittle.

Yes, some edge bits are flaking off when you handle it, like chrome slivers.
I am very careful as to how I handle it as I appreciate it is a very fragile device.

Quote from: PaulLowrance

What's the sensitivity of your temperature probe?

Tolerance I think is 0.2 C at 20C changing to 0.05 C at 40C.


(http://i100.photobucket.com/albums/m25/kingrs/DSCN4736.jpg)
(http://i100.photobucket.com/albums/m25/kingrs/DSCN4737.jpg)


Regards

Rob

Hi Rob,

It is fine to extend the coils, but it will make very little difference. If we understand how closed loop cores react to magnetic fields we know that the wire locations make very little difference unless you are talking about very high frequencies. Also it is the magnetic field from the wire that enters the core that makes nearly all the difference. FEMM simulation is DC current on a closed loop core, so extending the coils will only make a slight difference.

The reason I used Iron instead of creating a Metglas property is for two reasons:

1. The permeability of Metglas is not 600000 at 30 KHz. More like ~10000.
2. It takes a lot of time and it was a quick job; i.e., I'm spending far too much time on such things when I should be working on the "smoking gun."

The only way you could make the FEMM more accurate than mine is if you create a metglas property for the core and k-factor the coil current way down to adjust for the fact that the cores permeability drastically changes at 30 KHz. Also extending the actuator coil will help a tiny smidgen.

My Metglas samples arrived. :-)  Two of them no less, lol! Although they are very small and round toroids, but that's fine since I am testing the MCE theory, not the MEG. Also I asked for a different material, 2714AF, which has nearly zero saturation Magnetostriction, <<1ppm, and annealed permeability of 1 million.  Now if I can just get some time to work on it. I did not ask for the same material because you had already ordered it and it seemed highly unlikely they were going to give out a huge 320 core anyway. My goal is to first analyze the material to see if it is has high potential as the 2605SA1 (Naudin's core). The material I really want is Hitachi's Finemet. Man that stuff has "free energy" spelt all over it!!!

Attached is a very poor picture of the two MP3210P4AF cores. Sorry, my camera is very poor. There are two toroid cores and come in plastic cases. I removed one of the plastic cases so you see the core material.

Regards,
Paul Lowrance

Hi Rob,

I think you're right that starting with solid wire is best first option. Stranded wire is probably better in the MHz region. At 30 KHz it would probably just add more wire resistance. Solid magnet wire with really good electrical insulation sounds good. After all we're talking roughly a thousand volts.

BTW, my Metglas 2714AF cores have an inner diameter of 0.78 inches.

About two weeks ago I place a sample request for Finemet, but Metglas contacted me and said, "I received notice from our sister company, Finemet, that you are also interested in nanocrystalline cores.  Did you have a particular core in mind?"  So Finemet is a sister company of Metglas. I was too embarrassed to ask for another sample, so I'll probably have to pay for a Finemet core. Do you know how much Finemet cores cost relative to Metglas?

Rob, now that you'll have a legitimate Naudin Metglas MEG do you think Naudin would reply to an email for possible pointers?  It sure would be great if he could get involved at least a little.

Regards,
Paul Lowrance

Hi Paul,
maybe could one use videotape as super thin core material ?

Or audio pure iron tape ?
There is then only a few mikrometer thick surface layer of this
magnetic material on the plastic tape background layer...

Or won?t this work ?

Thanks.

Regards, Stefan.