Carl's gradiometer: need some help!

[panzerfaust]

Hello,

I'm actualy trying to build the Carl's gradiometer from Speake kit.
I must admit that I'm realy a beginer in electronic!

1) What is correct wiring for R6 (5K) and R10 (1K) variable resistor?
2) Same question for each FGM-3 sensor?
3) I'ld like to add 2 leds in order to indicate which sensor is excited. What component do I have to add for this modification and what is wiring?
4) It is possible to put a LCD board instead of the speaker? What does this modification could consist in?
5) There are some additional parts in the kit ( 2X 33uF capacitors and 2X 56uHy inductor). It'is normal???

I need very accurate answer (where is + & -...), cause electronic is not my speciality at all!!!

Thanks for your precious help.

Best regards from France, David.

[Leto]

Hi David

1) & 2) My only advice here would be: check the schematic again and identify appropriate PCB pads.
3) & 4) probable not so hard to achieve, but forget about it at this stage.
5) these are parts of two L-C filters to be mounted near FGM sensors..

sorry no + - answers

>>just passing by>>

[panzerfaust]

Carl's gradiometer: need some help!

Thanks Leto.

Please forget question #5. I've just found the answere in the technical document written by Carl...It was so clear however!

Other questions still remain problematic for me , don't hesitate to help me.

Best regards, David.

[panzerfaust]

Carl's gradiometer: need some help!

Hello,

Question #2 is now solved!

Anybody could help me for folowing questions? Carl, maybe

1) What is correct wiring for R6 (5K) and R10 (1K) variable resistor?
2) I'ld like to add 2 leds in order to indicate which sensor is excited. What component do I have to add for this modification and what is wiring?
3) It is possible to put a LCD board instead of the speaker? What does this modification could consist in?

Thanks a lot. David.

[Carl-NC]

Hi David,

1) What is correct wiring for R6 (5K) and R10 (1K) variable resistor?

Not sure what you mean, the wiring is given in the schematic. Also see the parts placement (Fig. 9).

3) I'ld like to add 2 leds in order to indicate which sensor is excited. What component do I have to add for this modification and what is wiring?

It's not a question of which sensor is excited, as they both are. It's a question of the difference in excitation, that is, one sensor will be higher (faster) than the other. Pin 2 of IC1 indicates this, so it could be used to drive 1 or 2 LEDs to indicate which sensor is stronger. Hook up like this:

VCC2---4.7k---aLEDk---[to IC1Pin2]---aLEDk---4.7k---GND

The 'a' and 'k' on the LED denote anode & cathode. Depending on the LEDs you use, you may need to adjust the R values for brightness.

4) It is possible to put a LCD board instead of the speaker? What does this modification could consist in?

Sure! You could replace IC2 with a micro and program it to drive an LCD. But if electronics is not your specialty this will be exceedingly difficult.You could also use IC2-Pin16 to drive a simple digital voltmeter.

- Carl

[panzerfaust]

Carl's gradiometer: need some help!

Great! Lets go to work !!!

Many thanks Carl.

[damiafix]

Panzerfaust, your Gradiometer work correctly?

All the best, D.

[panzerfaust]

Carl's gradiometer: need some help!

Hi Damiafix,

I just switch on my gradiometer. There is a continuous sound. Threshold pot seems to work well because it affect the bip rate. Volume pot also work.
For the moment, gradiometer doesn't detect large ferrous target (like a car). So I need to run the "adjustement and cal" procedure as soon as possible.

What about your's? If you have some tips to share with me, don't hesitate!

Cheers, Panzerfaust.

[damiafix]

I've built the probe, and now I'm calibrating and adjuting the FGM-3: look here:

http://www.geotech1.com/forums/showthread.php?t=15863

Best Regards, D.

[fitz]

Carls Plans..

Could somebody guide me to a link for Carls plans. I have the kit on the way but I can't find the plans anymore. I had them and now????
Thanks.
Fitz.

[damiafix]

Hi Fitz,
look this:

http://www.geotech1.com/pages/mag/pr.../fmx1/fmx1.pdf

Best regards, D.