Basis passive detector

[mustefa ubram]

hi to all
I am busy designing a long range locator Based on passive detector .but i need to info about Basis passive detector .Please guide me about passive detectors.
Why is named passive detector?
what is passive detectors?
What do they reveal?
for example this schematic of nicolas :

[FrancoItaly]

Hi Mustefa

A passive receiver only amplifies a signal, there is not a transmitter; it can be tuned to a single frequency or broadband , I think for use as LRL (as in my LRL and I think in the PD and in the other) is required internal oscillator that serves as a reference. In practice, the "phenomenon" acts on the internal signal which is then amplified. In the Alonzo PD the only "Lrl part" is the ferrite stage, the ferrite is "tuned" in null mode and the TR stage with TR coil is the reference signal. If the trasmitted signal is too strong it can decrease the sensitivity. In the Alonzo PD many parts are not necessary. The only critical part in a lrl is where the "phenomenon" interacts with the passive receiver, the PD is the ferrite, in my is the 3 turns coil and the stylus antenna.

Best Regards

[Nicolas]

Hi Mustefa you can test it

here the scheme tested with 68kHz

[king40]

Hi nic
You tested this schematic and worked ?
We can use this for test any frequency ?

[Nicolas]

Hi nic
You tested this schematic and worked ?
We can use this for test any frequency ?

Yes my friend I have tested it and work. But I not know if it work in your country. but If not work need find the real frequency in your country to tune it.

You must try it in your field test

[king40]

It need tx or working without tx ?

[Nicolas]

It need tx or working without tx ?

Only Rx receiver not need transmitter dear friend. we have all world much transmitters then not need that.We need only receiver to receive the resonate frequency or phenomena.


You can read this:

All metals specified above form a static electric field around themselves that can be detected from the ground surface. The distance of detection varies according to size, conductivity, depth and period of stay underground. Metals with high conductivity, such as gold and silver, are detected more easily since they form a larger electric field and the device can locate them from a distance.

Induced currents produce secondary electromagnetic fields, which can be detected on the ground surface through amplified deviations of the normal field woth very low frequency. Electrons also travel in a wave that can be located from distance. The highest reading over an object visibly stands out from neutral ground.

[king40]

Thanks nicolas
I start to build
Vr1 for battery low
Vr2 for what ?

[Nicolas]

Thanks nicolas
I start to build
Vr1 for battery low
Vr2 for what ?

VR2 is an POT potentiometer value 22K or 47k for tuning your PDK

[king40]

Thank
I better use normally coil or ferrite antenna ?,

[mustefa ubram]

Thank
I better use normally coil or ferrite antenna ?,

hi king40
We need to sense electromagnetic.i think feritte antenna is the best .

[mustefa ubram]

hi
Is this reasoning correct?
How is the position of the transmitter coil relative to the antenna ferrite?Top? bottom? Left?right?

[WM6]

hi
Is this reasoning correct?
How is the position of the transmitter coil relative to the antenna ferrite?Top? bottom? Left?right?

In principle correct, but, do you know, how to exclude direct impact TX coil signal to RX stage?

And of course: battery supplied receiver cannot be named "passive detector", cause it if very active (at least in amplification). It is simply "receiver".

[mustefa ubram]

In principle correct, but, do you know, how to exclude direct impact TX coil signal to RX stage?
.

I think controlling the output power of the transmitter And adjusting the ferrite with tx coil.
this is new circuit of passive detector:

[WM6]

I think controlling the output power of the transmitter And adjusting the ferrite with tx coil.
this is new circuit of passive detector:

By controlling transmit power you imply mainly to induced amplitude in RX coil, but at the same time to damping useful signal too. So this is not real solution. But in principle we do not need big power too.

By adjusting RX coil (coil on ferrite rod) position in regard to TX coil position is right approach.

In fact you need to null out TX signal from your RX front-end (RX coil) much like we do in case of IB DD coils.

For better results RX windings on ferrite should not be to long. Ferrite centered to TX coil position. Best to make 2 or 3 TX coil with different diameter and chose combination with best results.

Your drawing is excellent basis to represent this nulling procedure: