Calculating a METGLAS transformer

  • Last Post 24 February 2020
cd_sharp posted this 21 February 2020

Hey, everyone

I don't know how to calculate a METGLAS transformer. I remember some 6-7 years ago I read some stuff about how to calculate SMPS ferrite transformers.

Since many people here have METGLAS cores, I think this is an interesting topic.

My first thought is to attack this subject using the theory behind ferrite transformers.

There is a lot of theory and I remember it's full of math. I'll go directly to the end formulas.

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Chris posted this 21 February 2020

Hey CD,

I sent you a PM with this info in it, a Thread I posted sometime back: Transformer Math

I believe you are on the right track! Transformers were Floyd Sweet's specialty! He knew them inside out and back to front.

On my website and in the comments in the following video:


I posted two quotes I feel are very important:


On rare occasions, Sweet saw this effect, called self-oscillation, occur in electric transformers.

Ref: Jeane Manning: A New Physics for a New Energy Source / Free Energy - Making the Impossible Possible


Sweet was also a transformer designer and expert, and he remarked that he had also observed specialized self-oscillation in certain transformers.

Ref: Energy From The Vacuum by Tom Bearden



The Transformer Math is a start, its a few footsteps in the right direction to solving the fully mathematical solutions to building these machines.


cd_sharp posted this 22 February 2020

Hey, man! The only thing I believe from what Bearden said is that Floyd was a top expert in transformers. He saw the effect in transformers, but he decided to work with magnets. How misleading is that!

I do not believe in magic things and I know you do not either. The activated magnets sound like magic things.

Thanks, buddy

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cd_sharp posted this 22 February 2020

Hey, guys,

Alright, let's deep dive! We are interested in square wave with a duty of about 10%. I'll do the calculations for Hitachi AMCC-200.

We have a formula to calculate the number of turns in the primary coil:

Npri = Vin * 10^8 / 4 * f * Bmax * Ac

The main concern is not to saturate the core. This happens if the magnetic field density generated by the work of the transformer exceeds the maximum density supported by the core, Bmax.

Let's see what is Bmax for Hitachi AMCC 200 according to the datasheet.

A Bmax value of 1 T = 10000 Gauss should be well within the safe interval.

Please keep in mind this applies to a transformer, so It's about the flux moving during the on-time. I'll analyze what happens during the off-time also.


I fixed the datasheet link to point to the right alloy and I fixed the Bmax value. I'm also thinking about making a calculation for the suitcase device we saw from Don Smith. Stay tuned.

Fighter posted this 22 February 2020

When I first bought AMCC-200 I was searching for this, Hitachi have some software tools for this. I don't know how good or accurate they are:

Chris posted this 22 February 2020


Hey CD,

I do not believe in magic things and I know you do not either. The activated magnets sound like magic things.


Exactly, you hit the nail on the head my friend: I do not believe in magic things!

Any sufficiently advanced technology is indistinguishable from magic.

Ref: Arthur C. Clarke


Magnet Conditioning is a Hoax, I am 100% positive on that! What purpose might the Magnets have? We have already touched on this in other threads, but we can prove the Magnets did not make the Machine start or stop!


The VTA can be started by momentary connection of a 9 volt battery to the drive coils when the machine is operated in the self-powered mode. The operation is stopped by momentary interruption of power to the power coils.

Ref: Walt Rosenthal


Yes, you have to read between the lined sometimes, take what is possible and what is likely and work with that!

Best Wishes,


cd_sharp posted this 22 February 2020

Hey, guys

Let's move on. Ac or cross-sectional area:

First I thought it is Ac = d x a , but I was wrong because they are C cores with round corners. At the right hand side we can see Ac = 7.8 cm2.

We have all we need to calculate the primary coil:

I use a frequency subset that I believe is important for my setup, taking into account the Timing thread and suggestions from Vidura and Chris ( I just hope I understood this part correctly ). The number of turns is rounded to closest non-zero integer value.

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Chris posted this 22 February 2020

@All readers,

I have build some software to do all the Math, all you have to do is type in the numbers. I am happy to share if you guys want a copy?

This is only the Transformer Math, not answers to the entire machine.

Best wishes,


cd_sharp posted this 22 February 2020

Hey, man

I'd love to have it. I'll also share the Excel file when I finish.

cd_sharp posted this 22 February 2020

Alright, moving on.

If we round downwards the primary coil turns we must verify Bmax is not exceeded. I added the "Primary coil turns raw" which is the actual calculated value. I also added "Bmax" column to calculate the maximum field density based on the rounded turns number.

For example, for 16kHz we stay way below the supported density of the core:

But, if we decrease the frequency:

At 3.2 KHz the value I took as maximum accepted density is exceeded. At 2666 Hz it gets very close to 1.56T which we have seen is the maximum B in the datasheet of the Metglas 2605SA1 alloy.

Thanks for reading, I'll be back tomorrow with the calculations for the secondary.

cd_sharp posted this 23 February 2020

Hey, guys

If the input voltage is 12V and the duty cycle is 25%, the effective voltage that the secondary coil sees is :

V = 12 x 0.25 = 3V

It's a very important detail in any device that uses partial on-time.

I'm using a frequency-duty cycle subset important for the device I'm working on. Let's see what's the voltage the secondary coil "sees", the "Effective input voltage" column:

Vidura posted this 23 February 2020

Hi Cd and all following. It is a good approach to calculate design parameters , EE. use mathematics a whole lot to build transformers. Yoelmicro was teaching me a lot of these thing's. Thank you very much Yo! As you might know already, I have my difficulty with the math's, but the basic concepts are straight forward for me. Now we have to take into account, that conventional EE mostly use the magnetic materials well in its linear zone, that means with a important safety margin from saturation. An exception is the saturable reactor. But the design lines and calculations for different types of transformers will always keep us in the linear region of permeability of the core. This is not likely what we need  for building an AU device. Those who payed attention to earlier posts will have noticed Yoelmicro have mentioned several times the area of a negative slope of permeability, related to some successful machines. He formulated a hipótesis,  which now already supported by many practical testing, have become a theory. I am not in the position to release this work, as I'm not the author. He told that he soon will post this theoretical work on the forum. The point is that we might need to pass the limits of EE design rules and bring our machines  parameters much closer to core saturation for example. This also means that not necessarily conventional transformer windings ratios apply. Those more experienced with transformers will know that for example in flyback topology other formulas will apply, as there is no direct energy transfer at on time. So the stored magnetic energy in the core(and the environment) is released at the off time. So this will be calculated more like an inductor than as a transformer. This post only for the purpose that you don't wast your time building conventional transformers, although they might have three coils  this does not necessarily mean that they are asymmetrical regarding action-reaction. Regards Vidura.

cd_sharp posted this 23 February 2020

Hey, Vidura

I read your post without breathing. Seems like there are wonderful news ahead.

This post only for the purpose that you don't wast your time building conventional transformers

I'm not, I'm just trying to get the voltage up as much as possible as efficiently as possible at the end of the on-time.

cd_sharp posted this 24 February 2020

Hey, guys, finally

Secondary voltage is the voltage we want to obtain in the secondary coil.

Based on that we can calculate the voltage ratio, also known as transformation ratio.

Multiplying the voltage ratio by the rounded number of turns in the primary we obtain the number of turns in the secondary.

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The great Nikola Tesla:

Ere many generations pass, our machinery will be driven by a power obtainable at any point of the universe. This idea is not novel. Men have been led to it long ago go by instinct or reason. It has been expressed in many ways, and in many places, in the history of old and new. We find it in the delightful myth of Antheus, who drives power from the earth; we find it among the subtle speculations of one of your splendid mathematicians, and in many hints and statements of thinkers of the present time. Throughout space there is energy. Is this energy static or kinetic? If static, our hopes are in vain; if kinetic - and this we know it is for certain - then it is a mere question of time when men will succeed in attaching their machinery to the very wheelwork of nature.

Experiments With Alternate Currents Of High Potential And High Frequency (February 1892).