Protek Gtx 711

[Jeg]

This is my project. I used a 534 khz ceramic oscillator instead of 800 khz as the latter is very difficult to find. Also, the receiver has difficulty of receiving the transmitter signal unless the receiving coil is positioned near to the tx coil. I think the Rx needs more pre-amp. Please i need assistance...

Hi Golden
Nice building skills!

What is your final conclusion for this circuit? Does it worth for building it?

[Geo]

These days i had one at my hands...... and measured the Tx frequency, it was 125Khz.

[Jeg]

These days i had one at my hands...... and measured the Tx frequency, it was 125Khz.

Thank you George! Really? That low?
So we are not talking about emission in the sense of radio waves. Does the device trace the phase shift between emitter and receiver??!!

[Geo]

Phase shift !!!.. no, i don't think.
Maybe a 2box for big objects and why not a receiver for phenomenon.

[Jeg]

Great Geo! Thanks for the info. Is there any possibility that 125Khz is a modulation frequency riding a carrier at Mhz? Length of antennas normally suggest a carrier at tenths of Mhz!!

[Geo]

Jeg, no modulation signal. The Carrier is at 125Khz.

Regards

[Jeg]

Thanks Geo
Then i wonder if the advertised distance is true!

[Geo]

Who is the advertised distance?

[Jeg]

Who is the advertised distance?

"ΟΔΗΓΙΕΣ ΧΡΗΣΗΣ
Ο χειριστής λειτουργεί το protek περιστρέφοντας το σ? ένα πλήρη κύκλο 360 μοιρών και λαμβάνει ένα διακριτικό ήχο και εμφανή ένδειξη διαπήδησης της βελόνας οργάνου όταν βρεθεί στην ευθεία με το σημείο της ανωμαλίας πεδίου , επίσης με τη μέθοδο του τριγωνισμού , μπορεί να βρει το σημείο της ανωμαλίας πεδίου .
Απόσταση ανίχνευσης : περίπου 330 μέτρα"


Unless you search for titanic, i find 330m a very optimistic statement!

[Geo]

Also Mineoro speaks for 1km but is it true???

[Jeg]

Also Mineoro speaks for 1km but is it true???

[Dubulumach]

BFO type. Sch has errors.
It's not problem to boost amplification - the real art of lrl is to boost precious signal s enough to be sharply detected wihout distrubing S/N ratio. Equivalent noise figure rise with square of two of desired bandwidth. So wide bandwidth collect lot of noise including precius signals of gold coins which would be simply flooded in the noise. Solution is one - narrowband receiver Very narrow.

[Geo]

BFO type. Sch has errors.
It's not problem to boost amplification - the real art of lrl is to boost precious signal s enough to be sharply detected wihout distrubing S/N ratio. Equivalent noise figure rise with square of two of desired bandwidth. So wide bandwidth collect lot of noise including precius signals of gold coins which would be simply flooded in the noise. Solution is one - narrowband receiver Very narrow.

Hi Dragan.
There is another one solution (as idea)...... play with the level of noise.
Τhink about it...

[omar]

Hello.
What is the technology behind this device? Is it effective?
Are the attached diagrams complete?
Because I noticed that the sensor transistor was disabled in the receiving circuit diagram. It needs a 150k resistor connected to the base to work. If there is any information or links that provide more clarification on this topic, please put them here.

Thank you.

[Pahom]

Hello.
What is the technology behind this device? Is it effective?
Are the attached diagrams complete?
Because I noticed that the sensor transistor was disabled in the receiving circuit diagram. It needs a 150k resistor connected to the base to work. If there is any information or links that provide more clarification on this topic, please put them here.

Thank you.

In which particular place of the circuit do you think a 150k resistor is needed? Indicate on the existing diagram what is on the forum.