Popular Electronics, Feb. 1969

[WM6]

US patents of John F. Sutton
5,311,198 Active antenna
5,296,866 Active antenna
5,015,963 Synchronous demodulator

2,747,152 Greene (see bridge portion of system)

[mikebg]

Pinpointer of NASA with BLACK HOLE ANTENNA.

Pinpointer with BLACK HOLE ANTENNA.
The block diagram of this design should be specific case of block diagrams in postings ##116, 60 and 16.

[WM6]

Pinpointer with BLACK HOLE ANTENNA.
The block diagram of this design should be specific case of block diagrams in postings ##116, 60 and 16.

Yes, should be, as Gold Gun too. Thanks.

[Qiaozhi]

Yes, should be, as Gold Gun too. Thanks.

The Gold Gun doesn't have a built-in transmitter. It is totally passive.

[mikebg]

The Gold Gun doesn't have a built-in transmitter. It is totally passive.

Yes, the Gold Guns AL707 and AL718 are passive metal detectors. For operation they need large signal from VLF station in searched region. They are primitive variants of genuine passive detector invented by Vaino Ronka and described in patent US3,500,175. Ronka uses second ferrite antenna for receiving reference signal and measures amplitude and phase of target signal.
Search WEB for Geonics EM16. The company produces sparate TX for using EM16 in regions where no VLF stations.

[starmoml]

Miniature_transistor_metal_detector

hi mike bg how are you my Friends?
Compare the photos Please
http://uplod.ir/a14p1c9z6shw/Desktop.rar.htm
or
http://www.uploadmb.com/dw.php?id=1376469874

[Melbeta]

Esteban, I have the same PRG Gradiometer schematic you have, and mine does not have the part information either. Do you have a schematic that has the parts identified with values, etc? If so, would you be so gracious as to send the revised schematic to Pondco at Aol dot Com??? I would be eternally grateful. Thank you, Melbeta

[ArchibaldSTM]

Look at the date of the last comment)))

[Qiaozhi]

Esteban, I have the same PRG Gradiometer schematic you have, and mine does not have the part information either. Do you have a schematic that has the parts identified with values, etc? If so, would you be so gracious as to send the revised schematic to Pondco at Aol dot Com??? I would be eternally grateful. Thank you, Melbeta

Esteban hasn't been on Geotech since the 7th July 2019.

[Alexismex]

Popular electronics Feb 1969 can be download easy from internet