Surfmaster discrimination

[nelson]

How we can make surfmaster to discriminate like in the video?

http://www.youtube.com/watch?v=pcp3I...ture=endscreen

[Qiaozhi]

How we can make surfmaster to discriminate like in the video?

http://www.youtube.com/watch?v=pcp3I...ture=endscreen

The standard Surfmaster can already do this, as can any other PI detector. You only have to turn up the sample delay. I suspect he's just added a switch to make it easier to change between two fixed settings.

[nelson]

Hello Qiaozhi and happy new year

I didn`t know that surfamaster can discriminate like in the video. So if you or anyone else can help me to mod my surfamaster (Silverdog version) i will be very thankfull.

Best regards


Nelson

[Qiaozhi]

Hello Qiaozhi and happy new year

I didn`t know that surfamaster can discriminate like in the video. So if you or anyone else can help me to mod my surfamaster (Silverdog version) i will be very thankfull.

Best regards


Nelson

The discrimination you see in the video is not ferrous/non-ferrous. It is conductivity discrimination. No big modifications are required, as you only need to adjust P3 (100k pot) to change the sample delay. Find the correct position where foil is rejected, and measure the value of P3. It is then a simple matter of adding a changeover switch that swaps out P3 and connects in a fixed resistor of the value you measured earlier.

[SVEN1]

What he doesn't show you is when you crank the delay to reject larger and then larger foil, you lose sensitivity to smaller gold ladies rings and chains. But you gain sensitivity to larger gold rings. On my homebuilt PI, not the Surfmaster I set the delay to eliminate most small foils that drive VLF nuts but still sensitive enough to pick up the small rings and chains.

[nelson]

Ok and thanks my frind.
So my mod is fine and i need to give a try, because my P3 is working thru a panel 100K potenciometer.

Thanks a lot to all who took the time to help me with my question

Best regards

Nelson