Quote:
Originally Posted by Funfinder
Well, I know how it would work, by very critical adjusted and powerful bfo - but I like to build some extra circuit for this. I guess at the moment the "pure" electrostatic detection still has to be modified.  |
This is cool - look what I've found by pure coincidence:
Quote:
Originally Posted by mikebg
(...)
Currently I'm about to rediscover and and redesign most sensitive BFO metal detector. Many believe that this primitive principle can not be upgraded more, but soon will be pleasantly surprised. Our Noise Induction Metal Detector is so sensitive and so discriminative that beats most complicated VLF metal detectors.
(...)
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It's from mikebg -> Tech Forum -> "Beyond" TGSL
http://www.geotech1.com/forums/showp...01&postcount=3
I guess with very sensitive BFO that can distinguish the change of 1 or even 1/4 Hertz we have the best chance for "everytime usable LRL".
@ J_P
thx for your interrest and I will tell you some details:
I guess the size of the plastic-bag doesn't matters alot, it's the charge status. This was just a simple demo, because i rubbed it (for about 3-5 seconds) to my own hair. Assuming my body and head was already negative loaded from the ground the bag got positive charge.
But this bag discharges every time when the detector comes near by invisible ions through the air and also very slowly directly over the wooden bush that is connected directly to the ground.
the same way some sensitivity was lost while I moved the digicam closer to the detector, but not much.
btw. I missed taking my second electrostatic detector incl. 20 cm round plate with me so I could have checked the difference.
about the heli:
This was a very spontanous filming - but I did hold with my left hand the detector with plate in front into it's direction while searching where the helicopter is with the right hand and my eyes on the digicams display.
btw. I could encode the clips with divx4 fast motion so they just had around 10MB but I decided for better quality encoding 'em with xvid codec (66 meg).
AND - I forgot this to mention the last time:
I tested if it would receive the signals of the switched on coil of the Garrett Ace 250 but - absolutly nothing!
I also didn't hear the slightest AM radio broadcasting stuff.
btw. I could make the "shortcut a battery test". I don't remember exactly but some of the guys here got 1 or 3 meter "spark signals" with an 1.5v battery.
I guess those have been the motors ignition-sparks the detector received (similar like thunderstorm flashlights) because those create a strong EM pulse within a very large frequency spectrum, startin already at Very Low Frequency. You also can hear such stuff with AM radio.
Perhaps the helicopters engine iron block also works like some electrostatic antenna and radiates them to the outside.
btw. I guess the pure electrostatic load of metal - especially if buried in wet soil - is far to low for detection outside of the ground! At least with this actual circuit.
Maybe the Mineoro is sensitive enough but we don't know for shure what (if...) it really detects. For shure it doesn't detect the electrostatic load between earth and ionosphere where the metal object could act like a shield, reflector or irritator because otherwise it wouldn't detect it from a large distance. And the north-south directivity seems to has something to do with the distorted flow of the earths magnetic field.
The early units did use magnetic ferrite antennas - so this would match. Perhaps I better invent some magnetic field detector...
edit:
http://www.geotech1.com/forums/showp...4&postcount=89
ANDREAS @ "
Alonso PD modification" wrote:
"A car run (out city) can detect up 200meters distance."
This seems to be the same like with my helicopter detection - of course because of it's extra position - even more distance.