FGM-3 Alignment and Calibration

[kt315]

GUYS DO NOT ASK ME THAT I HAVE NOT -!
you write me in pm - PM has NOT possibility to attach files -!!!!!
WRITE JUST IN FORUM AND JUST IN FORUM -!!!!!!
i have not full data on FGM sensor. thats is not my matter! i has not interest to what having zero luck information -!!!!!!
yes, i see it is simplest circuit but WHERE A DATA ON WINDING AND WHERE YOU CAN FIND OUT PERMALLOY PLATES???
NO SOURCE!!!!

PLEASE DO NOT OVERLOAD ME BY YOUR BARE REQUESTS!!!! PLEASE DO NOT DO ME HERE BRILLIANT MEMBER WITH 200000000 POSTS!

[Krzysztof]

Sensitive!

Hi Damiafix
Consider whether the ALU suppresses sensitivity.
Zoom metal forceps at a distance of 10 cm should exceed the measurement range (max / min).
It is to be sensitive!
Best regards Chris

[damiafix]

Hi Chris,
with the probe placed along the axe W/E (direction and level) and the VCO gain at the low value, I've read 0.15 volts on the DAC. I've placed the sensors in to a "V" aluminium. No much better results, than when I was placed the sensors in the pvc tube. I can hear a low frequency sound.
The performances in this moment are very low. I wish try again in another zone, better clean than this. I hope in best results.

Cheers, D.

[damiafix]

Many thanks Chris. I'll try again with this suggestions.

Cheers, D.

[Krzysztof]

Hi Damiafix.
Here, you not satisfied.
I have other systems MI, the probe - and I work for ATMega8 Atmel.
Practically the presence of small amounts of metal in the area is unavoidable. If you do calibrate the MAG is finished you drive changes to a minimum (0 is the laboratory). Any change in your position and your meter has changed the outcome.
Position horizontal in the W / E you get results close to 0, assuming that the probe without regulation is on the line W / E.
If a mistake is the resultant outcome will be the sum of two different positive and negative deviations.
Therefore, it is safest to rotate the pipe as a gradiometer W / E around its long axis by 180 deg for control tuning.
In practice, after tuning on the line N / S have indicated on the LCD unit 2000, and the vertical pozycjii about 4000 units, this is normal in physics. Vertical component of the magnetic field is in my area 44.8 mikroT box full 49mikroT, horizontal component of N / S 20mikroT.
During the measurement of any deviation from the vertical gives the wrong signals (at high sensitivity), in addition to EMI interference and the presence of AC pulse does not make life easy for the operator.
Fitz may be right to set the probe in the same plane (FGM3 are not symmetrical), but have one of the are calibrated to the same axis.
I will know the results.
Best regards Chris.

[damiafix]

Hi Chris,
many thanks! Wow....you've put the circuit directly in the tube fantastic!
Please could you tell me if the alignment of the two sensors is ok?
Do you have misured the tension between the pin 14-15 of the DAC? How is the value?
Can you share some pictures of the sensor mechanism?

Cheers, D.

[Krzysztof]

Hi Krzysztof,
many thanks for your reply, can you share some picture of your mag probe?

Hi Damiafix
A few photos.
As the foundation of the electrical system 47mm is a pipe inside the pipe 50mm with a central vacuum cleaner, still experimental version that easy to dismantle and change.
Polls in the treated plastic shaft (thermal insulation and preservation of the axis).
At the same time loads on pipe further stabilize the equilibrium (as the camera operator handle TV).
Battery 3.7 V from Nokia, all the elements in the middle.
I am already unhappy with the length (105cm) because I have to bend down.
Joystic is good in the portable phone, but this will be useful in the design
of the buttons as Fitz - the need for resistance. Do you have any suggestions for a good small type inserted from the top?
Best regards Chris.

[damiafix]

Hi guys,
someone was able to measure a voltage of 0 volts between pins 14-15 of the DAC? My best value is 0,2 - 0,18 in some case. It's enough?

Best regards, D.

[damiafix]

Hi Krzysztof,
many thanks for your reply, can you share some picture of your mag probe?

Cheers, D.

[Krzysztof]

I greet, I am new in discussion; my english only from translator.
My attentions to settlement of sensors:
1. Finished, complete gradiometr 1m over the ground in line E / In in sincere field (minimum EMI).
2. turn over 1 sensor round his axis on minimum of signal.
I take the care about stiffness of pipe (diameter 50mm from installation of central hoover, the length 1,2 m);
neither! the metal in neighbourhood of sensors, copper lines, thin, as the furthest from axis of sensor, the tight sensor in rolled out plastic cylinder ( the axis + the thermal isolation).
In position of work (vertical) the signal is always ( the initially large difference of magnetical field), really we to place the minimum frequency of acoustic signal can now.
Best regards, K.

[Leto]

I am wondering if the internal components will still be out of alignment due to manufacturing differences. If this is the case I will still need to add adjustment screws. Does anybody have an opinion on this?
Fitz.

Fitz..
Leave one of the sensors adjustable..
with alignment of sensor you do not only adjust sensors on on the same or parallell axis but you also null out rest of the circutry, batteries etc.. so the axis of sensors will not truly match at the adjusted, working device.
You want to skip the fun with alignement of FGMs?

[damiafix]

I think that the sensors, inside, are different from each other, so a teoric linear aligment could not be perfect in pratic, for this reason. In this period I'm busy, so I can't continue the experiments with my mag...hope in the next days.

Best regards, D.

[fitz]

"perfect" is not always perfect is it, or is it?

I am working on a plan to have the sensor mount machined from a 5 foot piece of 2 inch round acrylic plastic. The ends will be center drilled on a lath. This means that they will be perfectly aligned when mounted. But I am wondering if this is really “perfect” as only the outer case of the sensors will be “perfect”. I am wondering if the internal components will still be out of alignment due to manufacturing differences. If this is the case I will still need to add adjustment screws. Does anybody have an opinion on this?
Fitz.

[fitz]

Thanks

I have already had a new idea and am looking into it. Because thermal is such an issue I need to get more mass into the mount. I am looking at getting a piece of 2 inch bar stock and having it center bored. Then I will have the ends where the sensors sit milled down so I can mount it much like I would have with the angle aluminum. I am going to draw this up and send it in for all of you to look at.

[Leto]

Do I need to adjust both sensors or will one do it???
Thanks
fitz.

Leave only one sensor adjustable .. or:
1) you will have hard time adjusting both sensors at the same time
2) you will double the chance that one of the sensors accidentially move in latter use