my PPM survey procedure

[Willy Bayot]

Hi,

For those who would be interested, I have taken the time to put on paper a summary of the procedure I use to make my own surveys.
Willy

[BillA]

Thank you Willy

[carthage]

Clair target

Hi Willy,

As I can see the data tables and the graphic is great and you for sure you know what you are looking at . For myself and probably for some other people would like to be able to read and understand our data after getting it in our computer for analysis.
Would it be possible and easy to tell the difference between steel, silver or gold data, and to see the target clearly in the graph?
Regards


A.K

[Willy Bayot]

Hi Willy,

As I can see the data tables and the graphic is great and you for sure you know what you are looking at . For myself and probably for some other people would like to be able to read and understand our data after getting it in our computer for analysis.
Would it be possible and easy to tell the difference between steel, silver or gold data, and to see the target clearly in the graph?
Regards


A.K

Hi,

I am sorry to disappoint you but a PPM is ONLY able to 'see' magnetic material like iron,cast,stainless,magnetite...
It is completely blind to non-magnetic material.
However, it is used in searching gold because gold is usually located in or around magnetite or iron ore.

On the graphs, any iron material is seen a a disturbance of the local earth magnetic field value, thus shown as regions where the lines of level are more or less close to each other

Willy

[Unregistered]

LNA and Filter circuits

Willy, I was looking at your various preamp and filter circtuits. You have several different versions. Which one is the best performing circuit? There are several versions but no explaination of why you published/used them, what the differences are or which one is better performing, or any descriptions such as the design notes on gains, bandwidths, etc. Can any of them accept a .5uV level signal and produce a usable output? Is there any of that information on your site? Thanks

[Willy Bayot]

Willy, I was looking at your various preamp and filter circtuits. You have several different versions. Which one is the best performing circuit? There are several versions but no explaination of why you published/used them, what the differences are or which one is better performing, or any descriptions such as the design notes on gains, bandwidths, etc. Can any of them accept a .5uV level signal and produce a usable output? Is there any of that information on your site? Thanks

The two pre-amp's in the chapters 4 and 5 of my PPM guidelines document are circuits proven to be working well although the one based on the paired low noise transistor LM394 is better than the one using the cheap 2N2222A.

An input signal of 0.5µV is REALLY tiny, I have no practical experience with such small signals. We usually get around 1µV from our sensors but we tune them. This tuning process creates LC circuit with a Q of around 50, thus giving a usable signal of 40 to 50µV at the input of the pre-amp.
What do you want to do with those circuits?

Willy

[Unregistered]

Build a mag

Thanks for the reply. I want to build a proton mag and so wanted to know the design parameters of your circuits rather than build them blindly. I went ahead and built the circuit utilizing LM394 transistors. I put a voltage divider at the input and fed my signal generator in. My measurements show a gain of 12000 in the first 2 transistor stages. This sure seems awful high. Did I build it correctly? Thanks!

[Willy Bayot]

There should be a small bug in some component value. Those two stages were not designed to give this high gain before going thru a pass-band filtering.

Willy