FGM 3 sensor

[ramin]

Does anyone here know what old equipment I can take vitroperm tape from ??

Since I do not have access to buy this

[mrkhrdr]

Davor,
Yes, I understand that those thin strips of metal embedded in paper are amorphous ferromagnetic metal of some sort. Someone posted instructions for taking these apart so you can get at the thin strip of metal-glass inside. That said, I have no idea which material they are made of; probably more than one kind, if there are more than 1 mfr. of these. The companies/brands are MetGlas (USA) and VitroPerm (Europe). Hitachi manufactures a nano-crystalline ferromagnetic alloy that they naturally claim is superior for some applications. They all sell their products in cores (the thin strips are wound around and over each other to build up the toroids and other shapes. I haven't pursued it very far yet, but I think I may be able to get samples to play with.

[Davor]

How about the anti-theft tags?

[mrkhrdr]

The cores have to be ferromagnetic, and air is not. In any event, a ferromagnetic material concentrates the magnetic field around it, as though the field follows the path of "least resistance". Think of an electronic current flowing in a poor conductor like carbon in which a good conductor like copper is embedded. The copper will in effect short-circuit the carbon, and if you measured the resistance of this device, it would be much lower than carbon alone. Not only that, but the detailed magnetic properties of the ferromagnetic material are important to the operation of all these types of devices, not just fluxgates. In brief, the relationship between the degree of magnetization of the core and the field applied around it is non-linear over some range of the former. It is precisely that nonlinearity that produces the signals that are dependent on the external magnetic field strength.

[Orbit]

I threw out FGM approach ,After much experimentation I was not satisfied ,how to change position compared to the constant magnetic field by changing frequency fgm 3 sensors and leads to inaccurate readings I am also disappointed in the FLC 100 ,He is frequently stable But with him I was unhappy with sensitivity ,,It caused me to change my approach all this and make your own design sensors that is super stable and the ability to be changed sensitivity necessary !

[Orbit]

Super Sensor System ,,adjustment
sensor 10yt to 200yt

[mrkhrdr]

amorphous metal cores from old switching supplies?

The various manufacturers of toroids made of metglas, vitroglas, nanocrystalline metals, and ferrites present plans for using their products in switching power supplies. If power supply manufacturers have been following these suggestions, there ought to be toroids and other shaped cores made from these materials in computer power supplies, no? Has anyone torn apart dead units and retrieved cores from them to experiment with?
Related - given a core of unknown composition, can you find out what it is? The basis of most designs is the B-H curve. How would you measure the B-H curve of a material?

[mrkhrdr]

Orbit's FGM & some questions.

Orbit,
Congratulations ! I am impressed by the professional look of your instrument and the 3D graphics of the results.

I'm just beginning to design my fluxgate, and I have many questions for everybody. I think that plotting the object in 3D is the way to go if you are prospecting or searching for something. Trained geophysicists can do this with their ppm instruments; very sensitive, yes, but scalar measurements only. Did your algorithm solve the mathematical inverse problem of determining the perturbing system- the target - given the input (earth's field) and outputs (magnetic field measurements)? Or did you assume something, such as the measurement vectors pointing directly to the target? As you know, the target has it's own magnetic dipole induced by the earth field, and in opposition. Since the target field presents a dipolar field, it will almost never point directly towards a detector on the surface, unless the 2 are separated by a very long distance (like the earth's field), in which case it's very weak. On opposite sides of the target, its field either strengthens or weakens the ambient field. Thus, multiple measurements must be made around the surface above the target.

Some questions about the instrument: Did you use the ICs provided by Speake for the instrument? Fluxgates that I have read about superimpose a frequency at twice the input frequency. That frequency doesn't vary. Its RMS magnitude does, and this is measured, converted to decimal by an ADC, and then computer processed (in an open loop detector. See my other links for papers that describe other approaches, especially closed loop designs.) From what I've read about the FGM3, it's the frequency that depends on field strength, so there must be some processing of the f & 2f output of the fluxgate itself. It seems as though the Speake ICs digitize the 2f frequency and send that word to a controlling CPU. But that raises the important issue of ADC resolution. From the schematics, it looks as though only 8 bits are output from the detector circuits. That would mean the frequencies and the field strengths they represent are quantized into only 256 levels! If you are building a serious tool for the uses we have, not a physics demonstration, this is inadequate. Bartington also makes fluxgate probes and instrumentation, and they strongly recommend that users of its probes digitize with 24-bit ADCs. That's a resolution of 1/16 ppm! I don't know if the FGM3 can output such small signals with reasonable SNR and absence of jitter (which will appear as deviations in frequency). But it shows what some fluxgate designs are capable of. Enough questions for now. Good luck in your venture. I'll send my own comments with some ideas I found in the literature and product descriptions.

[fmtemp]

Fgm3 coil description

Hi,
Should it be possible to have a more precise description of the coil winding ?
Are the two coils wound one they on the other? what is the meaning of the winding? Is the number of turn 2000 ?

Thank you for your answers

[tjmlena]

Hello Orbit:

What kind of software do you use to plot your pictures ???

[Orbit]

unit

[Orbit]

unit

[Orbit]

target of 1 first row of the 1 first step ! target 2 ..8 eighth row the 7 seventh step

[Orbit]

target of 1 /2 meters and 40 centimeters ,,target of 2 /5 meters and 30 centimeters in the tunnel target of 2 ..50 cm by 50 cm !! geoskan !!! SUPER SENSORS !!! flc !!!

[Orbit]

That it is possible you're right ! I'll see what day of the test site in the country ! greeting!