some cosiderations

[Qiaozhi]

This is a serious question - Does this BFO have a transmit circuit, or is it just the local oscillator section?

BFO is transmitter-receiver, 2 in 1.

Also, why doesn't the detector detect objects behind you as well as in front?

Good question. First, because the person acts like a screen. You're connected at earth through your shoes. Second, in back part of coil is another circuit wich acts as screen. So, the BFO is adjusted with all the metal parts as electrolitic, screws, PCB, RF shielded transformers, etc.

Thanks Esteban.

Also, I note in your photo that you are not wearing headphones. Does this detector have a loudspeaker or perhaps a meter?

[Nihil Roma Maius]

Thid said Esteban to me (or I'm Esteban) :

The detector has an audio gen. tone with speaker, first models with transistorized flip-flop as tone gen.

Why BFO? In early times this was common detectors. So, later we use IB, off-resonance and primary experiment with PI. And other kinds no-based on regular MD.

For today is enough! Go and work!

[Esteban]

Nihil, stop! Grrrrrr!!!

[Max]

Why don't you scan the schematic instead ?
and post here...

What for? If you're VERY SURE THAT IT DOESN'T WORK, so, why do you want it?

Max, you don't understand my intention. I post the pic of presse because is the unique pic of this model with the controls we can see more easyli.

Sorry, Max, yes, strongly I say you that a stable BFO in conjunction with other circuits make operable BFO at regular distance. If is martian for you, for me is normal. I learn other things by other and I know what I say.

Do you think for real you can read a 3ppm or 30ppm variation on an homemade/garagemade BFO ?

1Hz or 10Hz over 300Khz ???

Your memory falls. I explain very well you that non audible minielevation in sound before mix of 2 freqs. is the matter. You insist in your prejudices since your personal point of view and don't leave to explain, include against J_P and others. Here a post on another thread:


Is true if you expect in a BFO, for example, hear 100 Hz, 500 Hz or 1 kHz, so this is the difference when detection occurs. But with another additional circuit before occurs this "great" variation you can hear in amp stage a type of "breeze" and this isn't an audible tone. So, this minielevation in sound level before occurs real audible tone is the theme. Various times I wrote about it.

And yes, all are proofs. I don't see other person like me who can post pics with different electronic LRL managed by different persons since the 70's. If you're intelligent, also you'll see the progress through the time: first search head with cable attached at box and later integrated in an only body. What reason for to lie since more 30 years?

I like old BFOs... but what's "a good BFO" for you ?

You know: stable, all we know that, IN GENERAL, BFOs are not very sensitive.

Hi Esteban,
"What for? If you're VERY SURE THAT IT DOESN'T WORK, so, why do you want it? "

I'm sure it doesn't work locating metals from far away. That's my opinion.

But I think would be a good thing if you post it anyway... many other peoples here wanna se one of your design, to test it.

So why don't ?

Best regards,
Max

[Qiaozhi]

Hi Esteban,
"What for? If you're VERY SURE THAT IT DOESN'T WORK, so, why do you want it? "

I'm sure it doesn't work locating metals from far away. That's my opinion.

But I think would be a good thing if you post it anyway... many other peoples here wanna se one of your design, to test it.

So why don't ?

Best regards,
Max

Max, please leave this thread.
I'm trying to have an intelligent discussion with Esteban, and your constant interruptions are in no way helpful. Monitor this thread by all means, but please go and play somewhere else for a while.
Thanks.

[Esteban]

Oh Esteban you're such a tease!!! Did you get the email I sent you?

Randy Seden WD6ELU

Oh!!! Sorry!!! I'm in another part, the email is corporative, very closed in use outside the firm.

I'll read tomorrow and reply you.

Esteban

[Esteban]

Thid said Esteban to me (or I'm Esteban) :

The detector has an audio gen. tone with speaker, first models with transistorized flip-flop as tone gen.

Why BFO? In early times this was common detectors. So, later we use IB, off-resonance and primary experiment with PI. And other kinds no-based on regular MD.


Grrrr!!!! But the truth.

[Qiaozhi]

This is a serious question - Does this BFO have a transmit circuit, or is it just the local oscillator section?

BFO is transmitter-receiver, 2 in 1.

Also, why doesn't the detector detect objects behind you as well as in front?

Good question. First, because the person acts like a screen. You're connected at earth through your shoes. Second, in back part of coil is another circuit wich acts as screen. So, the BFO is adjusted with all the metal parts as electrolitic, screws, PCB, RF shielded transformers, etc.

Interesting.
Does this mean that the user acts like an earth connection through the handle?

[Esteban]

Each person has different resistence between handle and earth, for this is fundamental external controls as zero and/or sensibility.

Also (with some detectors, my simple IB homemade, don't know with others, e.g., famous brand), if you touch the negative lead of battery the MD go more depth and is more sensitive to small targets. Try! This is other discoveries??? or not???

[Max]

Max, please leave this thread.
I'm trying to have an intelligent discussion with Esteban, and your constant interruptions are in no way helpful. Monitor this thread by all means, but please go and play somewhere else for a while.
Thanks.

Hi,
I'll be here just reading for a while... to make you happy.

"I'm trying to have an intelligent discussion with Esteban"

wow... GOOD LUCK !

Kind regards,
Max

[Qiaozhi]

Hi,
I'll be here just reading for a while... to make you happy.

"I'm trying to have an intelligent discussion with Esteban"

wow... GOOD LUCK !

Kind regards,
Max

Thanks Max.

[Qiaozhi]

Also (with some detectors, my simple IB homemade, don't know with others, e.g., famous brand), if you touch the negative lead of battery the MD go more depth and is more sensitive to small targets. Try! This is other discoveries??? or not???

I must admit that I've never tried this, I'll do some tests and let you know if there's any difference.

[Nihil Roma Maius]

Hi,
Do you see the battery ???

Is a differential circuit for measuring the Earth resistivity.

So this is your LRL ?

WHAT A DISCOVERY !

Kind regards,
Max

No because also is in discussion conductivity an resistivity on earth. Be more intelligent, please!!!

Psss!!! Do you see the coils?

[Max]

Hi,
Do you see the battery ???

Is a differential circuit for measuring the Earth resistivity.

So this is your LRL ?

WHAT A DISCOVERY !

Kind regards,
Max

No because also is in discussion conductivity an resistivity on earth. Be more intelligent, please!!!

Psss!!! Do you see the coils?

Hi,
well the coils... uhm ... YES! I see them.

But you maybe miss some understanding of the circuit.
Let's explain.

The coils+compass are there just to avoid using a zero centered differential micro-amp-meter (or nano-A-meter, pico-A-meter ).

In ancient stuff like this... often happen to see a compass like the one of above. Just cause that way you realize a kind of "homemade differential ampmeter".
Actually the right terminology for it is "galvanometer", but instead of a coil moving the needle indicator in a permanent magnetic field (like in the D'Arsonval's galvanometer) here coils are fixed and is just the permanently magnetized needle moving due to magnetic imbalance at the coils.

The coils here have nothing to do with detection of signal, like you have in metal detectors or other things... are just used to deflect the compass' needle. Nothing else.

So, it's still an Earth Resistivity Meter... but of many years ago.

You have to center it for a non-target condition... then variation of resistivity (indication by needle) could give you an indication that an anomaly in local resistivity is present, due e.g. to a metal target or also an hollow... etc etc

WHAT A DISCOVERY !

Kind regards,
Max

[Nihil Roma Maius]

The coils here have nothing to do with detection of signal, like you have in metal detectors or other things... are just used to deflect the compass' needle. Nothing else.

Ohhhh!!! Le grand docteur!!! Thanks for explain me somethings i don't know!