Really sensitive pinpointer for grain size objects

[Detectorist#1]

Also, I use one small round board with soldered "Delay" potentiometer used for very heavy soils, ON-OFF switch and piezo sounder.
It's more convenient when these parts are soldered on additional PCB instead to be fixed only on the upper PVC cap of the pinpointer.

[Detectorist#1]

As I know, Surf PI starts as pinpointer project.
My project uses similar ideas. Also Barracuda project is very similar.
Let's with our common efforts, we make real successor of these two great and widely used projects!

[Detectorist#1]

Yes, these projects are pointed for DIY peoples, but I think, most of metal detecting enthusiasts haven't deep knowledge and this information will be useful for them

[Detectorist#1]

This is the file of PCB ASSEMBLY (Layout) of rev.D of schematic

[pito]

1.5mm ball update
https://www.youtube.com/shorts/o0Ogg_Sb0Q4

[Detectorist#1]

Hi Carl,

For the clamp diodes, I have been surprised from your statement that the low power schottky diodes are slower than 1N4148.
Today, I soldered simple tester ( schematic is attached). The results are very clear. You are right!
Thank you - you pay attention for this phenomena for me. In popular books, the authors claim that NO diffusion capacitance in forward biased schottky diode.
I just found scientific paper with explanation of diffusion capacitance in forward biased schottky diodes. (Abstract of the paper is attached)

[Detectorist#1]

Hi DIY enthusiasts,

This project is started as pinpointer's solution for grain size objects but no problem to be modified to simple PI MD for new people in this area. Increasing of the diameter of search coil to 8 inch (20cm) and changing the values of the damping resistors (the values depends from the type of the wire and the type of the isolation) will be enough to made simple PI MD as start point in this exited hobby!