IN 1980-81 (B & W PHOTO)

[Esteban]

Close-up of long distance radar MD for gold and silver. Miguel MontanÃ*a Grinok (my cousin), with the detector. Many of the photos I'm colected have secuences.

The apparatus sometimes detect copper, nickel and bronze coins, but only at very short distance, two or three meters, but gold and silver coins, rings, etc., was detected at 30-50 m, and the depth is no problem, easily 2 or more meters. The only time I see to detect bronze coins at 10 meters from the detector had explanation: in the place we found 12 good quality bronze coins.

If I decide to publish a book under the title, for example, "The parallel history of metal detection" (with many photos), will be success? Any idea from your part? There are publisher in USA for this?


Some years ago, this kind of SIMPLE apparatus are dismantle for to keep the secret. My first trip was in December 1979 (had 20 years old!) and we found many objects, include a small treasure consist in 55 pieces of gold and silver jewels and gem stones.


Wait no disturb my intromission. Please, if disturb, let me know.


Sincerely,


Esteban

[okantex]

Hi Esteban
Do you have a schematic of this kind of radar based MD?
good days

[Esteban]

No, but basically is a stable BFO, radio, alarm, classifier... Here the crude parts:

[hung]

Hey Esteban,

Is that Mr. John Baldwin with your cousin?

[Esteban]

Hi Hung. No, here is Mr. John Baldwin in this 2 photos:

[Geo]

Very Good.
But ... where are you Esteban ???
Regards

[gold24h]

I would like to build one of these,what frequency does the transmitter transmit and the receiver receive?

[okantex]

Hi Estebanif this pistol detector is a kind of BFO
where is the reference oscilator coil?
and why why there is a antenna in radio part.
and does it work when it is turned to ground(what we do when pinpointing with mineoro)I wonder its dept penetration in this position.

[Esteban]

Hi, the reference coil is in the black head.

In the radio is the called "classifier".

[okantex]

Excuse me ,I am just tryiing to learn about electronics you know.
if refrence osc. in black )also beat osc must be in bleck because it is the one we use in bfo),so what is the antenna for in radio ?
clasifer must get signal from beat osc. ,if not what is the cable for between black and clasifier?

[Esteban]

Search coil is the front, the circuit is in the black head, include the fix oscillator with his coil. The zero is make with precise tandem. This circuit is linked to the aluminium box with the shielded cable, in where is the radio and classifier control with potentiometer.

Variations there are severals, but the principle is equal in the major part.

[gold24h]

Can anybody explain how this works,does it resonate the buried metel.The black part must be a transmitter,it is possible to transmitt a signal in the air at say two watts power and receive the signal at a mile or more for mhz frequency range,but how could the signal go from the air then enter the ground where the metel is and cause it to resonate.If the metel was truly resonating you could receive the resonated signal from a mile away with a good receiver.