Nice video, can it be used as a mineral detector ? eg: Finding Copper, Manganese, Iron, Siver, Gold, Specially for finding Chromite deposits.
@karhukivi
Жыл бұрын
There is a fundamental mistake made in this video. The measurement must be made in the direction of the primary magnetic field, i.e. along the tape placed on the ground. The minimum signal is when the instrument is at a horizontal angle of 90 deg to the magnetic field as shown in the video. The operator then turns 90 deg to the right or left. This must be done consistently throughout the survey, always facing the same general direction for measurements, which must be noted - very important! The instrument is then raised to an upright position and rotated in the vertical plane, with adjustments to the phase angle ("quadrature") control until a minimum audio signal is obtained. The reason for using the minimum signal (and then turning 90 deg) is that it is impossible to determine the maximum signal strength from the audio output.
@ProspectorFrank
8 ай бұрын
I have a Sabre model 27 VLF EM receiver given to me many years ago, I believe this model was manufactured in Vancouver B.C. Canada.
@karhukivi
8 ай бұрын
That is very interesting indeed! Can you give me a few details of it please? How do you change frequency, what weight, what EM parameters are measured (e.g. tilt angle?) are there any images of it on the net? - I'm looking now. Thanks!
@Francois_Dupont
3 ай бұрын
what is it normally used for? do you use this to locate pipelines or something?
@karhukivi
3 ай бұрын
@@Francois_Dupont There are pipe locators which use a VLF signal as well as having their own in-built transmitter. But this instrument (and the others like it) are used mostly for mineral and groundwater exploration..
@tommytriglav5181
4 ай бұрын
Can you be so kind to tell me where I could buy one. I need 19.8 khz. Thank you have a terrific day
@karhukivi
3 ай бұрын
Iris Instruments (France) or GEM Systems (Toronto). There are many Geonics EM16 analogue units out there but getting a tuning for 19.8 kHz might be a problem.
@tanyalove6983
3 ай бұрын
Hi do you know where I could buy one or do you know where there is an electronic schematic of one? Thank you❤
@karhukivi
3 ай бұрын
Iris Instruments (France) make a TVLF instrument, I don't know what the price is today, probably €15,000 or more. It is a radio receiver and the schematics are not usually available from manufacturers.
@tanyalove6983
3 ай бұрын
@@karhukivi Thank you I will try to go with sdr and attach to Android phone. Then I can play around with the antennae and use the decibel Meter which looks☺️a lot more accurate than a ghastly sound. Lol. So thank you and I shared my ideas with you I think it is sharp ++ for the android. I will try ferrite core antennas like there is something with antenna for less than 5.00 that measures 40 60 and 77 khz so I will try linking the 40 60 antenna maybe two in series to get a longer antenna and if that dies not work add a variable capacitor or use the preamp from those time cards that have the antenna to it cheers
@karhukivi
3 ай бұрын
@@tanyalove6983 The modern digital instruments use several directional air-cored coil antennae to sense the tilt angle and compute the phase angle between the horizontal primary field and the secondary fields. The advantage of the audio nulling tone from the analogue instrument in the video is that the human ear can discriminate between the transmitter tone (MSF) and other interfering signals in urban areas. Good luck!
@tanyalove6983
3 ай бұрын
@@karhukivi would you have a schematic of it? Are you saying an air core wound antenna is more directional than a ferrite core one? I do not have 15,000 for one. Lol. And I have to find the gold mine to survey first. Lol
@twoupinya
Жыл бұрын
you did not turn 90 degrees to the primary field.
@karhukivi
Жыл бұрын
Yes, a common mistake!
@KORYAAL
Жыл бұрын
Which company is it???
@gkpgeo
Жыл бұрын
Very old equipment
@karhukivi
Жыл бұрын
@@gkpgeo But it works very well, easy to use near EM noise sources such as industrial installations, is light, to carry, very easy on batteries, works in arctic and desert conditions where "modern" instruments are often in trouble!
@karhukivi
Жыл бұрын
Geonics ltd. Toronto, Canada.
@Francois_Dupont
3 ай бұрын
@@karhukivi what is it used for? i dont seem to understand how hearing "by ear" a VLF signal could help a human find water or whatever. the wavering propagation and environment influence would sway the signal alot.
@karhukivi
3 ай бұрын
@@Francois_Dupont It is used to locate conductive water-filled fracture (fault) zones or mineralised vein at depths of up to 60-100 metres. The VLF radio signal induces a secondary alternating magnetic field in the conductor and this tilts the combined signal (primary from the transmitter and induced secondary from the conductor). The receiver is rotated until the audio signal disappears and the angle is measured with a clinometer on the instrument. Newer instruments do this automatically. The tilt angle data gives the location of the conductor and an idea of the depth and dip. Google on "VLF-EM mineral exploration" for more details and articles.
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