In-coil pre-amplifier

[Achillion]

As a Mini Pulse design experiment I'm considering to build the pre-amplifier as SMD in the coil enclosure together with the basket weave coil.

The idea is that this will reduce capacitance and sensitivity for external not target signals picked up by long cables.

I've set up an experiment to 'tie' an Arduino nano to my Goldbug 2 and detect sub gram gold. No noticeable difference with or without Arduino mounted on top of the coil.

Well the Goldbug is a VLF machine and I can only guess how this would go with a decent Pulse Induction. (unfortunately I don't have one)

Would someone be able to do this test and provide some empirical evidence.

Just curious to understand how a stationary tiny SMD circuit board could reduce sensitivity and outweigh the benefits mentioned before.

Feel free to talk some sense into me if needed.

[Carl-NC]

Putting the preamp in the coil works fine and won't cause any problems, just make sure you keep traces as small as possible and avoid any trace loops.

[Silver Dollar]

The Deux has a relay, battery and PCB sitting inside the coil and it does a good job seeing targets.

I have had trouble with heavy alu shielding reducing sensitivity so I don't know how they tune those Deux's..

[golfnut]

they dont use heavy ally sheilds.

graphite / carbon and drain wires

[golfnut]

If I had time and interest I would like to have a go at doing the preamp and demods and atods in the coil and pipe the serial data out to the control box over a polymer fiber.

The deus has a weakness that it dont work well in water as the rf link fails - the fiber should be ok

like the xp. a lack of coaxes would give no emc / pickup opportunities.

Any dsp/signal processing/computation/LCDs could all thrash away belching out broadband noise with no degradation to the delicate target signal integrity.


There would be the opportunity to repair the 'cable' (fiber) by just unplugging and swapping it out!