Pinpointer technology

[JoyJo]

Greetings to all! I got the information on the Sphinx pinpointer. X-ray of the sensor and some photos of the printed circuit board. I was interested in the input part: why is the pinpointer coil turned on through the electronic relay? Or is the coil shunted on the relay to extinguish the reverse eds?

[Skippy]

Pinpointers have a tendency to behave like large targets when turned off, if they have a tuned frequency similar to the detector. ( for example the Teknetics T2 /Fisher F75, at 13 kHz, are not too compatible with the Garrett Propointer , about 13 kHz ).
Shorting out the coil with a relay contact changes the resonant behaviour of the pointer, so no pickup problems occur. Disconnecting it from the tuning caps would also work.

[JoyJo]

So this is done only so that in standby (or sleep mode) mode the main metal detector does not perceive the pinpointer as a search object?

[JoyJo]

Good. The second question is about the same pinpointer. The pin sensor has 3 pins: two pins are connected to the ground, and the third pin is "signal". There are no questions with the signal output. The second coil output is connected to the ground. It doesn't raise questions. And here's the average conclusion! If you look at the X-rays, you can see that the "middle" output connected to the ground is simply laid along the axis of the ferrite rod. What does such a technical solution give?

[JoyJo]

Do pinpointers shield the entire coil? Maybe it's the contact conductor for the graphite shield?

[JoyJo]

The xp mi6 has only 2 outputs at the pinpointer coil: no screens are observed. The AI did not offer anything useful about shielding the pinpointer coil. Does it make sense to have only one conductor along the ferrite rod, for example, to remove the static charge?

[Carl-NC]

It looks like the coil is wound with bifilar wire and the third wire would then connect to the center tap at the nose of the winding.

[JoyJo]

Then why connect two terminals to the grounding ground? Why connect two coil leads to the ground?

[JoyJo]

This end of the wire is not connected anywhere.

[Carl-NC]

Never mind, I see now it's a 2-layer coil. No idea about the third wire.

[Skippy]

The third wire will be a screen / shield .... however, don't be surprised if it is UNDER the coil winding, not OVER it. I've had a Garrett Propointer AT ( carrot ) apart, and that is how that appears to be constructed. I've no idea about your Sphinx.

Also .. the very high mu ferrite material that will no doubt be used in a low-freq gadget like a pinpointer, will be electrically conductive. So there MAY be an electrical connection directly to the rod.

[JoyJo]

Interesting! And why is it necessary to connect the ferrite rod to the ground?