Carl's fluxgate Gradiometer ckt.

[Geo]

Hi.
Really i don't know what to say!!!!, a lot of stranges phenomenons. Connections are very good. Voltage at pin 1,3,4 is to +5V. No short circuit... .
I put the sensor on a wooden chair and turn on and after self calibration i put a iron object near to sensor. What is happening????
Some times the leds turn on but don't stay on....
Sometimes they stay on (this is good). When i put a iron pincers near to the sensor the frequency is goes lower, but when i put a coffe metal box the frequency goes up (not all the times). What is happening???? The times who work ok i saw that it need a frequency shift of 1Khz so to have the blink of the first led, so i believe that it need more sensitivity.

Regards

[damiafix]

Hi,
are you sure that is possible to dump the program from the SCL007?
I think of no, but for this I leave the word to Chris that is surely most expert of mine!
About the SCL007 integrity I still suggest you to check again all the connections, in my FXM-1 in a first time, I believed that also my SCL was damaged, but after few test and controls, I've found that all was ok. I remember that an evening I had the same problem that you have described, the problem in my case was a not solid contact, close the sensor; please check with attention the connection between the sensor and the pcb with a tester, if is ok, try with the other sensor. Yes, is possible that the SCL007 is damaged, but first of this conclusion you should control with much cure.
Check again please.

All the best, D.

[Geo]

Hi Geo.
Not necessarily corrupt SLC07. Maybe without showing a large load current outputs. May again be reset / configuration, and therefore sets a very high level as the primary signal. Try what the impact of PIN1, 3,4 - theoretically to Vcc. Is it because you FGM3H very large range of frequency changes. Or slide a little iron from the sensor. Normally the output signal level should be constant under specified conditions, not dynamic. Remove the stand ADC, may burden the SLC? Search for short-circuit or low power SLC (maybe a bad solder and is much resistance?).
Best regards Chris.

Hi Chris.
As i remember first times who i made it, it worked good except the VCO who did not liked to me. I will check all around the SLC, but so little components or nets so to make problem!!!. Btw... do you have the hex file of the SLC???? or can you take it from your SLC07???

Regards

[Krzysztof]

Hi Geo.
Not necessarily corrupt SLC07. Maybe without showing a large load current outputs. May again be reset / configuration, and therefore sets a very high level as the primary signal. Try what the impact of PIN1, 3,4 - theoretically to Vcc. Is it because you FGM3H very large range of frequency changes. Or slide a little iron from the sensor. Normally the output signal level should be constant under specified conditions, not dynamic. Remove the stand ADC, may burden the SLC? Search for short-circuit or low power SLC (maybe a bad solder and is much resistance?).
Best regards Chris.

[Geo]

Hi Damiafix and Chris.
I am sure that there is a problem.
I made the test with the Logical Analyser. So.... when the sensor is far from iron objects i have a square signal on the sensor with a frequency of 110Khz and all the leds are off or maybe the led at pin13 flash. When i let an iron object near to the sensor the frequency is going at 40...45Khz and stay there. The leds are going at "on" for a moment but they return at Off condition. So i believe that the SLC is faulty.
Your opinion????

Regards

[damiafix]

Hi Geo, Hi Chris!
don't worry Geo, this result is normal; in a first moment I was in doubt that some component could to be damaged, but after few test (suggested from Chris) I've understood that the mag was ok. You must to test the components, out from the pcb, please read the post 11.
The real problem, for my own view, is that this tool is not really suitable for field use, a real use, but it can to be a interested and inexpensive way for to understand as work a flux induction magnetometer, and for to enter in the magnetometry world, trough the door of the electronic diy.
For me, it's been a good experience but now I'm building the epe mag, I should to buy the pic and the lcd in the next days, the sensors are the same.

Good lucky, D.

[Krzysztof]

Hi Geo.
Damiafix had similar symptoms (#11). Assembly and PCB were clean.
He spread, he measured, he folded and it is OK.
These spirits are gadfly? Maybe brownies?
Maybe this this Jin which transfers treasures a bit further and deeply when it sees from PD someone?
Do not place metal near sensora quite. Max 15 cm. You cross range measuring SLC07.
To muffle the trembling of generator FMG3 maybe even, though little real.
Indication MAG have to be stable. In practice this devout wishes.
Best regards Chris.

[Krzysztof]

Hi Geo.
Read whole plot, small tests are there.
To take out DAC first and to measure levels H / L on exits D0-D7 on SLC07.
Pin1 to Vcc.Low sensitivity mode.
Leave on table MAG, to does not touch him! Pin 17,18 together, one sensor.
To measure D0-D7. They should be all zero.
To to bring nearer the piece of metal, iron then and to measure.
Then again nearer and to measure.
Quite near all exit D0-D7 bedą level H.
You can use "Mini Logical Analyser for poor". (post # 12).
This the good simultaneous review of levels and nothing costs. You do from Digitals a lot of it - will add.
When you do not touch anything then exit levels have to be solid.
You will to bring nearer metal they - grow and they become solid.
To jump D0 maybe or even D1 - then fault EMI. Just problem.
Give to know how it went.
I looked for several days this the beaten in in the ground of engine Me109g with war. Dusk dropped already, I hurried and measurements are doubtful.
I walked for quickly and unequatly. Map went out ambiguous. To correction in year. Field is already sowed now.
Best regards Chris.

[Geo]

Hi.
I have a problem with my gradiometer. I short pin 17 and 18 of SLC and connect one sensor. I put the sensor far from iron objects, I turn the unit on, let it for 10 sec for the calibration and measur the voltage on the pin13 of the SLC (with the DAC out of the pcb). Voltage is 0.00v, and if i will put an iron object close to the sensor the voltage goes to 4 or to 4.5 or 4.7V and then falls to 0V.
Is it right???

Regards

[damiafix]

Thanks Chris,
I'll try again.

Have a good day, D.

[Krzysztof]

Hi Damiafix.
Ah, the English.
Resolution FMX-1 is 256 units, because this is the data width 8byte (D0-D7).
Leave 2.2Kom is OK.
There is no need to use the switch to him.
The best is the logarithmic characteristics of the R6.
The worst characteristic is exponential because the too fast growing.
When you have a linear potentiometer R6 is just 2.5 Kom.
Best regards Chris.

[damiafix]

Hi Damiafix
Congratulations, good job!

Hi Chris, thanks!

The current use of professional MAG've never heard of someone doing the measurements in the race. Always it was a fixed position, height and vertical.

You have right, but this horizontal test was casually, I was ensuring if, after the insert of the switchs and the resistor, the gradiometer would be gone ok, infact I did the real test, after this, in the field.

Treasure hunters only did MAG lighter and went with him for a walk.
Comply with the rules and FOT9 FOT8 and will not be big problems.

Ok, I'll consider the suggestions of FOT9 and FOT8

A resolution: FMX-1 has a width measuring 8bit bus and do not change, ie 256 values. How well do you set the top scale is no more need.
PS.
You do not have the power to give way to 2.2 Kom, leave it and do adjust R6.
And there must be 5Kom already 2.5 Kom of the characteristics of linear enough.
Even better, if R6 = 5Kom find the characteristics of log [C].
These widely disseminated to the consumer electronics, have exponential characteristics[B], and this is really a suicide.
Best regards Chris.

I'm sorry Chris, I don't understood perfectly your suggestion, I should to disconnect the R2.2kohm from the PCB and adjust the R6, or leave it inserted and still change the R6, with a linear pot of 5kohm?


Best regards, D.

[Krzysztof]

Hi Damiafix

per understand if this tool could still to be improved, or if his limit is reached

Congratulations, good job!
The current use of professional MAG've never heard of someone doing the measurements in the race. Always it was a fixed position, height and vertical.
Treasure hunters only did MAG lighter and went with him for a walk.
Comply with the rules and FOT9 FOT8 and will not be big problems.
A resolution: FMX-1 has a width measuring 8bit bus and do not change, ie 256 values. How well do you set the top scale is no more need.
PS.
You do not have the power to give way to 2.2 Kom, leave it and do adjust R6.
And there must be 5Kom already 2.5 Kom of the characteristics of linear enough.
Even better, if R6 = 5Kom find the characteristics of log [C].
These widely disseminated to the consumer electronics, have exponential characteristics[B], and this is really a suicide.
Best regards Chris.

[damiafix]

Hi Chris,
hi everyone, I'm back from another test and finally I know in which modality, the SCL007 work in the original Carl design.
I've insert a switch for to change from Low to high sensitivity mode,
these are the connections for to give the two modality:

SCL007 Pin1 to GND: High sensitivity mode
SCL007 Pin1 to Vcc ( 5v through a 4.7kohm resistor) : Low sensitivity mode.

So, in the original Carl design the SCL007 work in Low sensitivity mode!

If I switch the SCL007 to the HSM, in the laboratory, with the probe placed orizontally
on the table, if I put close the sensor a little steel object (a pair of scissors) it "see" it from 1,5 feet (without the sensors aligned), so I think that it's a very good result!
But in the field, after the calibration and the sensors alignement, If I switch the SCL007 to the HSM is impossible to use the gradiometer, it's much sensitve at the probe movements and the rotations on the vertical axes.
I've insert also a switch for to use or to deactive the presence of a 2.2kohm resistor between PIN14/15 of the DAC and GND (like the Chirs suggestions).
In effect, after the calibration and alignment phase, if I use this resistor, the gradiometer is most sensitive at the little variations of the earth magnetic field, so I think that this resistor is a good fix, for to improve the performances of the original Carl's designe, but also with the resistence of without it, is impossible to use the SCL007 in HSM sin, becouse the gradiometer in this modality is most sensitive at the little variations, and it's very impressive for the performances!
In every case, I should to try again in a most clean land for a accurate result and detailed valutation.

All the best, Dam.

[damiafix]

About the sensitivity mode, would be much appreciated some clarification directly from Carl.

All the best, D.