Carl's fluxgate Gradiometer ckt.

[Krzysztof]

Hi Epitopios.
Hello again!

cables: no-where ,.................
no measure there

See post #19. The photograph you have eight lines from the center of a plate to the box, if they show something?

did you see better different from your Gradiometer with these changes ??

Cosmetic changes, better sensitivity and a nice sound. As if the rose or the steering level of sound (sensitivity range) at low frequencies.

you have a 9 volt or 12volt/7Amh baterry ?

I do not have FMG3, Carl MAG, MAG EPE. I have my own construction of the battery-powered mobile phone 3.7V 1000mAh. Shows no magnetic properties. Type BL-5c. I add to 5V converter to drive the LCD.
Best regards Chris.

[epitopios]

R6 to GND through resistor 100om - Security transistors.

You mean something like that ???
and also :

C7 = 2,2mF : IS IT ELECTROLYTIC CAPACITOR OR SIMPE ??
are everything correct ??
thanks in advance

[epitopios]

Hi Epitopios.
Hello again!

See post #19. The photograph you have eight lines from the center of a plate to the box, if they show something?

Best regards Chris.

dear Krzysztof , the 8 lines you see , I put them from the begining
and I just left them as it was , no reason
do you think I can use them ???
regards , epitopios

[Krzysztof]

Hi Epitopios.
Subject # 47 Fig1.
Do not.
Read # 26 Linia3-8. Test4, 5, 6.
Additional 100om resistor R6 the other hand, directly to GND.
Only for testing as a protection against short circuits Q1 in the case of R6=0. Then, exterior Q1 activation of voltage from another potentiometer. Serves to control the action of the V / f .
Subject # 47 Fig2.
Subject C7. Any type. OK.
I think I will improve the transfer of low frequencies.
Subject 1nF. Do not.
Read # 42 3rd Position.
1-10nF capacitor from this point to GND. In order to mute noise (jitter), and high harmonics.
Subject 2,2Kom. Do not.
Read # 42 1rd Position.
Listen to the # 41 MP3 from the sticky results Damiafix.
AD557 has an internal resistor 1.6 Kom and is still a little too big to stretch the scale at low frequencies.
I propose to give 2.2 Kom parallel between Pin14,15 and Pin13=GND.
Of course, R6 = 0 is removed.
In an experiment, you can just reduce the C5 up 3,3mikroF and C6 very much up to 10nF.
Best regards Chris.

[Krzysztof]

Hi Epitopios.
Response to post # 48th
Read # 12!
For the test on the table so qasi logic analyzer is very helpful. Can be used to test the digital lines and control drive the asking. Eats a little power on the table but do not mind.
Of course you can use these open eight lines D0-D7 to send them on the LCD but through an additional microcontroller!
Best regards Chris.

[epitopios]

Hi Krzysztof
I make some changes as you write.
Can you see them and rebuild the foto correct if somewhere Iam wrong ??

regards, epitopios

[Krzysztof]

Hi Epitopios.
50% bug's.
Since R6 = 0 is directly to the Q1 emitter Pin14/15. At the same time Pin14/15 resistor to GND 2.2 Kom!
1NF from the point of R9-R10 to GND. It is to be low-pass filter!
Dle experiment C5 3.3 microF. Please listen to the answer V / f to select the better / more sensitive.
Best regards Chris.

[damiafix]

Dear Chris,
this is part of the test 9:

one fluxgate FGM3 sensor connected, pin 17/18 of the SCL007 wired, and the logic analyzer connected on the pcb, r6 is around 4,5KΩ.

One sensor test


All the best, Dam.

P.S. I'm sorry for the video quality I've realized it with a easy photocamera.

[Krzysztof]

Hi Damiafix, TNX.
Give conditions how in # 52 and listen what difference!
Best regards Chris

[damiafix]

Dear Chris,
thanks again for your help, I've a question, about the inductors L1/L2 connected on the Vcc Pin of the two sensors:
I think that I've damaged one of this inductors, maybe the internal wire is broken (infact when I move it sometime work, sometime no) I've checked the welds on the cable, but the problem is inside the component, so for now I've replaced it with a 47uHy inductor, and it seem work correctly:




Reading the Carl's document about the FMX-1 I've found something of strange about the L1/L2's value, he wrote 56nHy but on the speake's components list I read that the value is 56uHy and that could to be replaced with a 10ohm resistor, look yourself:





Unfortunately here it's very hard find a 56uHy inductor like the original.
Please, could you tell me the function of this inductor?
In every case, I should to replace also the second inductor with the same component, it must to be equal, for a good work!
What do you think?

All the best, Dam.

[Krzysztof]

Hi Damiafix.
Power supply decoupling is typically always use. There must be the same. There may be several nH or a dozen om. It may be a few beads ferite. FGM-3 is resistant to changes in power to a limited extent but you can always go further to protect.
Moreover, the same as the generator produces a low distortion power line in moments of change in H / L and L / H output (jumping power change).
FGM-3 is much more sensitive to temperature changes. It is good to put it in a Styrofoam.
For the trials on the table, the lack of security does nothing!
Best regards Chris.
P.S.
Subject of the film. Discard R6 and add 2.2 Kom and you will have glitches at the beginning of the measuring scale.

[damiafix]

Hi Damiafix.
Power supply decoupling is typically always use. There must be the same. There may be several nH or a dozen om. It may be a few beads ferite. FGM-3 is resistant to changes in power to a limited extent but you can always go further to protect.
Moreover, the same as the generator produces a low distortion power line in moments of change in H / L and L / H output (jumping power change).
FGM-3 is much more sensitive to temperature changes. It is good to put it in a Styrofoam.
For the trials on the table, the lack of security does nothing!
Best regards Chris.
P.S.
Subject of the film. Discard R6 and add 2.2 Kom and you will have glitches at the beginning of the measuring scale.

Hi Chris,
I'm back from another test, I've removed R6 (AD557 PIN14/15 direct connected to the transistor Q1) and inserted a resistor of 2.2kohm between AD557 PIN 14/15 to GND, but the default output frequency is high, not at the beginning of the measuring scale, maybe R6 should to be replaced with a resistor of 5k, infact if i use this resistor the output frequency is most low, like the test 3j for R6=4.5kohm.

From the original Carl document about the FMX-1 I read:

The minimum output voltage of the DAC is 0v (when the sensors are
balanced) which should result in a silent VCO. In reality, the sensors are
never perfectly balanced so the VCO is always running at some low
frequency. It is actually desirable to have the VCO idle at a very low frequency. The reason for this is partly why the old BFOs were tuned up to run at a slow putt-putt frequency: the human ear is very sensitive to frequency changes. By running at a very low rate we can discern very minute changes; if we run it too low we risk getting a rate change that is actually too low to distinguish. A nominal rate of 5-10 Hz is a good operating point. Obviously this is below the frequency range of average human hearing (about 20Hz on a good day) but remember that the speaker waveform (E) is a square wave, not a single tone, so what we hear are “clicks.”
Because the square wave is rich in harmonic energy slight variations in the fundamental mean larger variations in the harmonics which gives us an even more effective frequency change.

but with only a sensor and SCL007 PIN17/18 wired I should to hear nothing, or some "clicks" like this ideal test for R6:5k and AD557 PIN 16: 02v, pratically, I hear a most high output frequency, like the video test that I've showed, why? It's normal?

All the best, Dam.

P.S. I've replaced the FGM3 flying connections with a most solid pcb:

[Krzysztof]

Hi Damiafix.
I heard the sound you should get the (highest) are already close to 0V! 100% agreement with Carl translation. As even at 0.5 V, still hear the tapping is to say that you lost 20% of the sensitivity of 0; because nothing but tell a knock. Why would you smash your head when the sensitivity of the treasure chest, you have to dig it!
Best regards Chris.

[damiafix]

Hi Damiafix.
I heard the sound you should get the (highest) are already close to 0V! 100% agreement with Carl translation. As even at 0.5 V, still hear the tapping is to say that you lost 20% of the sensitivity of 0; because nothing but tell a knock. Why would you smash your head when the sensitivity of the treasure chest, you have to dig it!
Best regards Chris.

Dear Chris, I'm sorry, I don't understood perfectly, so you think that my results are ok, right? Nothing of strange?
But with R6=0ohm when I power on the FMX-1, It start with a constant high frequency sound....it's ok?

Many thanks, Dam.

[damiafix]

Hi Chris,
I'm back from another test, but I'm still a little confused...for AD557 PIN16=0v (DAC PIN1 to PIN 8 "Low" GND) when the sensors are perfectly aligned no sound should to be hear:

The minimum output voltage of the DAC is 0v (when the sensors are
balanced) which should result in a silent VCO

so with only one sensor used (SCL007 pin 17/18 wired) when I power on the gradiometer, for R6=0Ω I should to hear a very low frequency sound:


It is actually desirable to have the VCO idle at a very low frequency. The reason for this is partly why the old BFOs were tuned up to run at a slow putt-putt frequency: the human ear is very sensitive to frequency changes. By running at a very low rate we can discern very minute changes; if we run it too low we risk getting a rate change that is actually too low to distinguish. A nominal rate of 5-10 Hz is a good operating point. Obviously this is below the frequency range of average human hearing (about 20Hz on a good day) but remember that the speaker waveform (E) is a square wave, not a single tone, so what we hear are “clicks.”



and not a high frequency sound; in my case, for R6=0Ω and a resistor of 2.2kΩ inserted between the DAC PIN14/15 and GND, I get a high frequency sound, while for R6=5kΩ I get a most low frequency sound, but for my personal opinion , still much high for a good pratical use, but maybe I'm in error about this impression!?!
Please hear yourself the results directly from the media player below, this is a easy test:
after that I've powered on the FMX-1, you can hear the different output frequency result for the two settings of R6 (0Ω and 5kΩ) and after the 10 cal seconds, I put a steel object close the FGM3 sensor, the gradiometer seem to work, but my doubt is the operative frequency work, becouse I think that the gradiometer should to work with a start low frequency sound, and not a constant high frequency sound (it's like a hammer on my mind) :


One sensor Test, R6:0Ω; R6:5kΩ

With all the components on the PCB and one sensor inserted I don't get the results of the previous test (DAC Pin16 close the 0v) when I could to hear the single low frequency "click" why?



Best regards, Dam.