question to all technician friends

[okantex]

Hi ALL
I want to learn something about detectors.
in article about BFO I read that phase shift in bfo's is about generally
between 10hz -100hz. and bfo s work about 100khz.
writer says if we decrease freaquency to achive high penetration.
phase shift will be smaller .and give this example .for 10khz working frequency phase shift will be between 1hz-10hz.but hearing it will be difficult for ear.so we can not decrease frequency much.

queation is that,
while we use VLF's phase shift must be similar to 1hz-10hz.but we hear it.
what makes us to hear this shift while useing vlf's.?
can we add this technical part to bfos

[Max]

Hi ALL
I want to learn something about detectors.
in article about BFO I read that phase shift in bfo's is about generally
between 10hz -100hz. and bfo s work about 100khz.
writer says if we decrease freaquency to achive high penetration.
phase shift will be smaller .and give this example .for 10khz working frequency phase shift will be between 1hz-10hz.but hearing it will be difficult for ear.so we can not decrease frequency much.

queation is that,
while we use VLF's phase shift must be similar to 1hz-10hz.but we hear it.
what makes us to hear this shift while useing vlf's.?
can we add this technical part to bfos

Hi okantex,
"phase shift in bfo's is about generally
between 10hz -100hz. and bfo s work about 100khz"
It's not phase shift there but frequency shift.
Phase shift occourrs too referred to a reference oscillator but in BFO freq. shift is used to detect imbalance and then phase shift (degrees) used to discrimination (where disc is present).

One simple method to achive best detection is converting small freq. shift in some voltage then using some comparator to show small differences. But a very stable reference required and also some PLL too (e.g. cd4046) - this way one can use 10KHz or also 1Khz or less.
Older BFO used directly the beat oscillation between tx and ref. osc. thus requiring 100KHz or more to have audible beat frequency---> audio tones of about some hundred hertz.
Anyway phase shift is only used for discrimination, not detecting itself.

Best regards,
Max

[okantex]

Hi Max
Thanks for your attention.
if we use same frequency ,voltage and current with any vlf ,can we achive the same dept.

[Max]

Hi Max
Thanks for your attention.
if we use same frequency ,voltage and current with any vlf ,can we achive the same dept.

Hi okantex,
VLF's are someway similar to BFO. I mean continuos waves TX...and other aspects. E.g. VLF-T/R like most best-seller tesoro or whites are really close to what I said...imbalance detection and phase discrimination, with TX frequencies of some KHz. Performances are also similar and big differences shows only with changing coil dimensions, shape, t-r configuration...
In BFOs what's important is frequency shift and beating frequency...disc can be achieved by freq. shift directly or watching at phase diff. (better)
VLFs are better than sinple BFOs because they are less sensitive to GND effects, often well gnd balanced and lower noise sensitive due to lower frequencies used. They are primary choice in disc hunting, where possible...but generally not so sensitive to metals in ground, at least in disc mode.
Older BFOs success is mostly related to using same radio-like technology (het receivers...beating...mixers...revealers...etc) but today hasn't any advantage on vlf mds where modern electronics can do easy signal processing in many different ways. Also "disc by tones" is an older behaviour mostly ignored in today market - that prefer other kind of indication (visual, numeric etc).
Anyway...,though similar one to other, VLFs can be really different in designs , components, coils configurations, balancing where present (ib like) and depth is , at the end, a function of many variables.

Best regards,
Max

[okantex]

Hi Max
Really thanks for your interest.
I am sure older members of this forums know what I want to do.
my father's friend had an interesting machine.
he and my father found a gold coin in a small mud cup at almost 4meters dept.when he broke the cup , a gas burned his hand.and still that burn is on his hand.
the machine stolen at the time of earthqueke in1999 TURKEY ,may be you remember.
then we found it but it was a mess junk.
that detector can discirminate 6 metals
according to panel it can detect up to 10 meters.and give dept.
in my opinion samll head (coil 6cm) can concentrate induction so taht according to flux density that reflected voltage ratio gives dept.
made of two parts.
one is radio like part for analysis ,it is not moveing in saerc area.just waits while other is searching.
search part(detector) has really small searchhead like cigarrette packed.
in search heaad there is a 9 volt battery.in handling box there area 4 1.5 volt battery.
in head there is also u2 u cores placed lke square.
at the center of coil there is iron metal piece
and also a kristal in head.
you can lokk this link .once a time I tried to copy as I can.
http://thunting.com/geotech/forums/s...ad.php?t=12036
I would like to try powerfull BFOs.
may be new generation modified BFOs.

[okantex]

and can you help me technically to modify a bfo .

[detectoman]

bfos funcionan en la equilibracion de las señales producidas por dos osciladores separados, a lo cual la presencia de un metal enterrado, cambia en desbalance, y en favor de la bobina grande de abajo y esa desestabilidad es manifestada en el alza del zumbido que predomina y proviene de ese oscilador y vlf funcionan por medio de trasmisor y receptor, algo similar a ib
yo creo que el perfeccionamiento de los bfos quedo inconclusa con la aparicion de los ib y posteriormente con los vlf y despues con los pi
sinembargo hubo en sus ultimos dias excelentes bfos como el arado y otro de garret
alguno que sepa español que traduzca correctamente esto para el hermano okantex

detectoman

[Max]

Hi Max
Really thanks for your interest.
I am sure older members of this forums know what I want to do.
my father's friend had an interesting machine.
he and my father found a gold coin in a small mud cup at almost 4meters dept.when he broke the cup , a gas burned his hand.and still that burn is on his hand.
the machine stolen at the time of earthqueke in1999 TURKEY ,may be you remember.
then we found it but it was a mess junk.
that detector can discirminate 6 metals
according to panel it can detect up to 10 meters.and give dept.
in my opinion samll head (coil 6cm) can concentrate induction so taht according to flux density that reflected voltage ratio gives dept.
made of two parts.
one is radio like part for analysis ,it is not moveing in saerc area.just waits while other is searching.
search part(detector) has really small searchhead like cigarrette packed.
in search heaad there is a 9 volt battery.in handling box there area 4 1.5 volt battery.
in head there is also u2 u cores placed lke square.
at the center of coil there is iron metal piece
and also a kristal in head.
you can lokk this link .once a time I tried to copy as I can.
http://thunting.com/geotech/forums/s...ad.php?t=12036
I would like to try powerfull BFOs.
may be new generation modified BFOs.

Hi okantex,
I think it could be a T/R type of detector. But difference between this unit and conventional t/r (2 boxes) could be that receiver is in a fixed position and transmitter is carried by operator.
Receiver part seems like long wave receiver with ferrite antennaes and coil balances.
TX seems having directional flux generator using core too.

Think that could be a good detector if flux intensity is really strong and concentrated in a small spot. (and ferrite is a good concentrer).

Don't know for sure but I think I saw something similar but can't remember now where ...a big black box...and a small hand-held detector...I think some german apparatus from WWII. I'm not sure.
But could be an evolution of this kind of detector , used in WWII for demining.

But 1 gold coin at 4 meters...wow. It's a big distance...but maybe like with 2-boxes halo can play a big role around the target, and also mud container.

Unfortunately I haven't any plan of the german unit. Can't say anything sure about schematic.

Best regards,
Max

[Max]

bfos funcionan en la equilibracion de las señales producidas por dos osciladores separados, a lo cual la presencia de un metal enterrado, cambia en desbalance, y en favor de la bobina grande de abajo y esa desestabilidad es manifestada en el alza del zumbido que predomina y proviene de ese oscilador y vlf funcionan por medio de trasmisor y receptor, algo similar a ib
yo creo que el perfeccionamiento de los bfos quedo inconclusa con la aparicion de los ib y posteriormente con los vlf y despues con los pi
sinembargo hubo en sus ultimos dias excelentes bfos como el arado y otro de garret
alguno que sepa español que traduzca correctamente esto para el hermano okantex

detectoman

I'll try to translate...(I can ? don't know)
BFOs work on the balancing of the signals generated by 2 separate oscillators...where if a metal is present underground...change in imbalance occourrs (?)... and this change at search coil is showed by an increase of tone that is stronger and came from this oscillator (?)...and vlfs work by tx and rx similar to ib too.
I think that the developing of BFOs was concluded with the introduction of IB and then later with VLFs , then with PI take place.
??In last "years" good BFOs like "arado" (?) and another from garret...

Well...I've translated...I think you want say that BFOs is a dead horse...but there are some good ones out there till now.

Best regards,
Max

[okantex]

Hi max
thanks for translation.why detectoman insists on his native language I can not understand him.

look at this link
http://www.intio.or.jp/jf10zl/wlmd.htm
there is a detector with radio reciever.

let say it my detector.in it according to it's user there was a kristal.
know I think different from the first link.
it is just bfo and the antenna is just beat osilator antenna.
transmitter and reciver at the same time.

as in this japan link it's osilator can resonans with a station in radio part.and can cause silence.when metal is found shift causes sound.according to shift machine can analyse metal type.
and also there is another evidence.it is that ,there is a part on radio with sembol Fi. it has three stage ,they look like a kind of potansiometer.
with playing them user can anderstand if the target is a mineral or metal ore.(or metal object)

[okantex]

can you do some changes on this japan projecet .

[Max]

can you do some changes on this japan projecet .

Hi okantex,
I built a 2-box similar some years ago...working on long waves and using a long wave radio receiver. It worked and actually detected water pipes a meters underground...but I had some problems with radar interferences...and other stuff...and anyway I don't like 2-boxes too much so dismantled it.

But I think that japanese detector is not good as your father friend, that seems well balanced in coils etc. where japanese is not...so giving much problems in operation e.g. positioning relative between tx and rx.

I think you need to find a good technician there in your contry to try to repair that detector. Unfortunately I haven't plans of the german-unit I
wrote about - but if I find them I'll send to you or post in the forum.
I think that german-one and what I see in previous forum are similar - at least for principle of operations.

I'd like to help you but at now I'm too involved in bandido to make modifications or testing other circuits. Sorry, have no time.

Best regards,
Max

[Geo]

Hi Max. If you will find anything about German unit, please send it to me.
I am interesting about Tx and RX frequencies.
Regards

[Max]

Hi Max. If you will find anything about German unit, please send it to me.
I am interesting about Tx and RX frequencies.
Regards

Hi Geo,
for sure I'll send you if I'll find them. Problem is I don't remember where I see it first time...many years ago. Don't know.

Best regards,
Max

[Esteban]

WWII German TYPE

Only have photos of this large detector. Also there are a book or report, don't know if contain plans or not, called Feuerwerker-Minenkampf in Nordafrika 1941-43. I want this!!! Is very possible that during Russian invasion much of these plans was confiscated by troops under special orders.