Epe pic magnetometer

[IC-77]

Sorry, Mr. Simons, there was some confusion or replace personal forum by some članoa, but I think it's still just a mistake and nothing else. Regards,

[ivconic]

[ivconic]

Funny thing!?
Iron pliers are nice detected only at upper FGM-3 area while not detected at all at lower sensor area.
And vice versa; aluminum tube is detected only at lower sensor area and not at all at upper sensor area!?
How about that?


I just finished this and it is in preliminary testing. Ultra simple circuitry with ultra simple idea... and yet gives interesting results!
I will have to change some things more on it further.
Until than...

[SimonS]

Very interesting!
How it possible to detect aluminium anyway?

[ivconic]

Very interesting!
How it possible to detect aluminium anyway?

I guess is not possible.
At the moment i was delighted... but few moments later i realized that there was iron bar inside aluminum tube! Daaaaamnnnnn!
But another thing here is interesting; "massive" iron pliers are detected only by upper sensor area and not also by lower sensor area, while;
not so "massive" iron bar inside aluminum tube is detected only by lower sensor area and not at all by upper sensor area!?
How about that?

[SimonS]

Maybe aluminium tube is like "shild". Try to remove aluminium tube and try only to use only iron peace how it work.

[ivconic]

Maybe aluminium tube is like "shild". Try to remove aluminium tube and try only to use only iron peace how it work.

No, is not the reason.
I also tested with several other items too.
Generally; small iron objects are detected only at lower sensor area while larger (and massive) iron objects are detected only at upper sensor area.
This "phenomena" is further emphasized because of the current electronics i hooked up on sensor, but generally this is one of the features of FGM-3 sensor, and i suspect that it has something to do with it's geometry inside.
There is certain "signal overlap" area, somewhere in the middle of sensor body and that's so obvious when experimenting with standalone sensor hooked up on oscilloscope.
I noticed that several years ago, when met these sensors for the first time.
Now, with simple electronics and few tricks, i am trying to use this FGM-3's "drawback" and turn it to certain benefit.

[ivconic]

Some checks and experiments with metglas tape.
Also checked "core" taken out from ordinary AAA battery.
Have heard somewhere that those battery "cores" are made from high permeability materials and also can be used in sensor coil setup... well, it seems this one i checked can't!
Anyway... it is interesting to see that coil with 12mH inductance can rise it up to 75mH with high permeability core inserted !

[WM6]

Maybe aluminium tube is like "shild". Try to remove aluminium tube and try only to use only iron peace how it work.

If this happen from vicinity it is ok, because FGM-3 sensor is not absolutely passive sensor like compass, it is in connection with target movement an active sensor, and can act as weak metal detector from vicinity too.

[rocco_k]

where to buy fgm-3.thanks

[SimonS]

You can look at site http://www.speakesensors.com
There is contact e-mail.

[lazzy]

Dear friends

some issues re the EPE mag logger:

I recently built a new unit (the original was broken...) and I have the following problems:

* the pic does not recognize either of the installed eeprom chips (message "0 eeprom chips"), even when only one chip is installed
* when the eepprom erasing function is invoked ('Null' + 'On' switches), the software shows that chip 1 and 2 are being 'cleared' but then continues with 'chip 3' (?!) and so on (probably, because no eepprom's were found)
* although the 'Record' function seems to work, no data are written to either of the eeproms
* no data are transferred to PC upon activation of the relevant function

The circuitry as well as all connections to switches seem to be ok; 5V is established where necessary, while all components were checked and seem not to be faulty.

The PIC (16F877-20) has been initially programmed with both Microchip's Pickit3 and Velleman's K8076 programmers; it was then re-programmed with the same devices, but without improvement with respect to the above behaviour.

One other thing to be noticed is that after some programming sessions, the PIC program was not working at all, showing only the message 'EPE Magnetometer, 0 eeprom chips' but no other function whatsoever; while, after some other programming sessions it functioned like the descriptions in the beggining of the post.

Finally, I tested the same PIC on two similar PCB's, and the overall behaviour is exactly the same on both boards (some times a faulty function, some other times no function at all).

Is this a problem of the PIC, of the programming, or of the board circuitry?

Any help would be much appreciated as well as any tips regarding the testing of the circuit.

TXs
lazzy

[SimonS]

No, there is nothing wrong with program in PIC. For some reason cannot read EEPROMs. If you have osciloscope you should check SCH and SDA line. If not, just look for some errors on boards. Do you have jumper under EEPROMs?

[lazzy]

SimonS

thanks for reply

I will check SCK/SDA but I dont think there is any problem - I do have jumpers under the eeproms

I agree that there is no problem with programming the PIC - the problem is on the board, either a faulty track design or lack of necessary components (such as some resistors...)

have you seen shansov's posts (#221-#223, posted in December 2012) regarding the same problem?
and his solution, putting a 10K resistor between IC6 out and IC4 pin#1, instead of the jumper?
have you tried this?

regards
lazzy

[SimonS]

On post write there was problem with jumper.
I sure there is problem on your PCB. Mine work fine. Can check power line, SCH, SDA? Or if it possible some hires picture of your board.

best regards
Simon