Hi there!......The original Sandbanks eh!.... Now we're showing our age.
I still have the first object I ever found with this PI. Memories come flooding back as I recall my patient endeavours with this DIY project.
Then came Eric's 'Sandpiper.'....a very functional little wobbly plastic shafted unit....but it did the business.
Now it seems that PI in its many forms is back in vogue, and being discovered again by the 3rd generation of detectorists.
Now the modern designer applies the newer technology of micro-processors to enhance its functionalities, but the truth is that the basic fundamentals are still relevant.
Its re-birth is due to the willingness of designers/manufacturers to apply a more sophisticated analytical engine, and change from mono loop to a Balanced induction loop.
Add to that the 'Candy' mathematical algorithms, and you have the 'appliance of science' versions found in the Minelab Explorer series.
Time marches on, but the hands on the clock still go 'round in circles', as does the PI principle. The only changes are, that newer clocks are 'quartz' controlled.
Even so.....it's time we supplemented our batteries with solar power, and also recorded our full days detecting on a 4 Gig. stick, with SAT nav.logging.
So come on Eric, Give this lethargic breed of detector designers a prod up the proverbial back-side, and drag them into the 21st century.
WE HAVE BEEN PROBING THE SURFACE OF PLANETS for over a decade or more....yet designers find it difficult to apply such knowledge to our hobby.
I DON'T WANT A MACHINE THAT TELLS ME IF IT'S a dollar or a dime, just tell me what the ground conditions are within the first 12 inches of soil.
In basic terms, THE SOIL'S CONDUCTIVITY FACTOR, and THE MAGNETIC SUSCEPTIBILITY.
Then let the detectorist learn to relate those effects to the depth, the size and metal recovered.
The two factors mentioned would be expressed in RELATIVE terms, compared to an industry/hobby standard.
Enough of that.........Let me ask a question of ERIC, and his published graph relating to his experimental Magnetic Viscosity Meter.
Examining the graph, in the hope of maybe answering queries from other readers, left me unable to draw any meaningful conclusions.
You showed a plot of MVM readings against sample delayed times.
The 'law of the curve' implies a relationship of some K factor who's amplitude decayed with time.
In more graphical terms, v =V*1/time. It is not of the usual exponential decay form, but rather 'v' being proportional to the inverse of the sample delay time.
One cannot comment further without knowledge of the circuitry involved and the test parameters applied.
Obviously, one cannot approach closer than within 10 micro seconds if you are using your usual design methodology.
I think you should have at least shown two more graphs.
Firstly, the output in the absence of a sample, then secondly, a second rock source typically from the UK.
Also, some quantification of each sample, by presently used methods.
Eric, what exactly do you think your MVM will reveal that is new to the science?
Whatever the outcome, I wish you success, and if it proves to be a more economical as well as simpler tool for evaluating soils/rocks then "Well done"..
Best regards...........MattR.UK.
