Strange damping on Surf PI 1.2 please help

[antalaz]

What do you mean by snubber? Where do you add it?

[Sean_Goddard]

10" 22 Turns of 16AWG magnet wire, tune the 1st sample delay and threshold. With an added snubber, my Silverdog SM PI picks up a .22 sized nuggest at 11" in airwith a good clear signal. If you push the audio then you can still hear a change at 14". Shield is sprayed nickel with a 2mm gap.

[antalaz]

Here is the curve of my coil.

I haven't shielded it yet, do you think it worth it ? is it a good coil in your opinion?

I've tested it on the beach and i've detected very small pieces of metal (almost as big as rice grain) but there is false signals due to the lack of shield.

[antalaz]

I finally made it, i'll post some pictures soon

Btw hebcom posted the right link

[hecbom]

Is this what you are looking for?

http://www.geotech1.com/forums/showthread.php?21466-Coil-for-the-Barracuda-and-SurfPI

[reptooyep]

I would like to setup my damping resistor and my delay,so i made some research on the forum and i've found a post from Tepco where he is explaining how to figure it out with a scope.

Hi,
It would be a VERY good idea if you share the link to this procedure cause i hasked the question few days ago in another thread without getting any clear answer ..
Thanks

[Ferric Toes]

With a decent size picture it appears that the scope has the AC input selected. Switch to DC to get a correct picture.

Eric.

[mickstv]

It looks under damped, it should look more like the yellow curve shown below. So you need a lower value resistor.

Also your pictures don't look right, check to make sure the ground connection of the oscilloscope is connected to battery -

[chemelec]

Pictures are TINY, hard to determine if correct or not.
Might also help if you post a link to those instructions from TEPCO.

[antalaz]

Hi everyone !

I've managed to build a Surf Pi from Silverdog' kits.
It's working quite good (it can detect metal, so the main function is ok I think )

I would like to setup my damping resistor and my delay,so i made some research on the forum and i've found a post from Tepco where he is explaining how to figure it out with a scope.

I'm trying to execute his instructions but when I try to visualize the signal from the coil, It does not looks like a "normal" signal.
You'll see more details in pics attached to this post.

I'm using an homemade spiral coil.

I'm sure that i'm not the one who encountered this problem.

Thank in advance for your help !