Need to ID this detector found at a Flea Market

[ivconic]

Thanks to the very detailed and well written article about this detector; Andy Flind left no room for improvisation in the interpretation of the principle of operation of this detector.
That's why one just need to read that article in detail and with understanding.
For the age in which the article was published; this was a very advanced project.
"...This project was published in the August & September, 1980 issues of Practical Electronics..."
Wave, Blisstool, Pirate and the most popular and best-selling among them: the Golden Mask series were later created on the basis of that project.
Everything that could be said on these topics has already been said on numerous topics here on forum.
...
For a start visit this:
https://www.geotech1.com/cgi-bin/pag...gnum/index.dat

[ivconic]

Comments/feedback/notes:
From Robert Mandara:
...

[Carl-NC]

making everything else a positive signal. = And what is not everything else? It is gives a negative signal?

In Ground mode, if it gives a negative signal for all metals then the circuitry was designed as inverting. You can design it either way. In Ground mode ferrous and non-ferrous should always have the same polarity, whether positive or negative.

In Beach mode, all you get is an X signal so ferrous is negative and non-ferrous is positive = my theory from post #23 it is ok ?

It's correct for all the modes. In Ground mode your signal would be the R channel on ferrite; in Beach mode it would be the X channel on salt; in Disc mode it would be the R channel on, say, a pull tab if the pull tab is the exact disc point.

[Daves]

Ground mode is an all-metal mode. Ground phase is about 0° and so the only thing you get is the R signal, making everything else a positive signal. In Beach mode, all you get is an X signal so ferrous is negative and non-ferrous is positive. In Disc mode you are moving the null point around; if it is set to pulltab then nail/salt/foil is negative and copper/silver coins are positive. You can design the detector to invert these polarities (I don't know what the Magnum does) but the physics is the same.

Carl, If Ground 0 phase = All metal
What is the 0 point in Disc mode?

[Carl-NC]

The plot shows raw phase responses, regardless of mode. Ground is always around 0°, a huge silver bar is around 180°. In disc mode you just set the phase where you want to transition between reject & accept.

[Daves]

The plot shows raw phase responses, regardless of mode. Ground is always around 0°, a huge silver bar is around 180°. In disc mode you just set the phase where you want to transition between reject & accept.

Carl, what is the range that would be considered the raw phase?

[Carl-NC]

0-180°. Pure magnetic responses are 0-90°, pure eddy responses are 90-180°.

[Daves]

0-180°. Pure magnetic responses are 0-90°, pure eddy responses are 90-180°.

what are the starting and ending raw phase angles for ground?
what are the starting raw phase angles for ferrous targets?
what are the ending raw phase angles for non ferrous targets?
in case 0-180

[Carl-NC]

Ground is typically 0-5° but can be as high as 15°. it has little variation with frequency.
Most small iron is 40-60° and can vary with frequency, mostly depending on its eddy component.
Salt is usually very close to 90° and mostly frequency independent.
Non-ferrous can be anywhere for 0° (tiny foil bits) to 180° (Atocha bars) and depends on frequency.
ITMD3 thoroughly explains all this.