surf pi test results (if anyone's interested)

[taliesin]

just finished testing surf pi.

i used the original schematic.tip32 ,using 7660 osc synced to the 555 .709

opamp in front.i used a 9v pp3 100 maH.(all i have at minute)
kitchen floor.
thresh min
delay fastest

50p =10cm
2p =9cm
£1 = 8cm
cufflink made from 2 solid silver sixpence = 5cm
1940 half silver sixpence = 6cm
5p =5cm
gold earing and a st christopher and chain approx 1gram total.= 0cm

[silverdog]

I didn't get great results with a 9v pp3 - 8 x AA works much better
What size coil are you using ? 8-10" works good

[taliesin]

I didn't get great results with a 9v pp3 - 8 x AA works much better
What size coil are you using ? 8-10" works good

23cm diameter coil, 20 turns made with 0.5mm (24 gauge).
i'm gonna try them silverdog thanx

[dfbowers]

23cm diameter coil, 20 turns made with 0.5mm (24 gauge).
i'm gonna try them silverdog thanx

Good choice on size! I have settled on a 9" coil, 19t with teflon coated, 7 strand 22 AGW silver coated wire. But for all practical purposes, magnet wire works OK if you are careful not to damage the enamel insulation.

Now, here's an observation I made yesterday:

The soil where I live is sort of a clay mix.
In my test garden, I have 11 buried .58 cal Minie balls, from 1" to 11".
I made sure that the ground was "clean" from any other targets before I buried them.

With my IB detectors, (Nautilus, Shadow X5, Tesoro Cibola, and White's XLT and TGSL the deepest that I can detect in the ground is only 7". Air test are probably 12" - 13" at best with the Nautilus. Going to all metal mode, a little deeper, but not much.
so, I can safely state that I loose a little under 1/2 of my depth in the ground.

Now, here is where things get interesting.. With the Surf PI and a 20us delay, I can only pick up the Minie ball at 8" in the air. In the ground, I can pick up to the last Minie ball at 11"! Just barely, but it's there..

To double check, I repeated my test in another area, same thing! Then, I opened a hole and put nothing in it just to make sure that disturbed ground wasn't causing a false indication. ( I actually planted my targets by driving a pole into the ground and dropping the bullets to the bottom). I have read other places that PI detectors can go deeper in the ground, and now I believe it!!

Another reason I like the 9" coil is that targets are a little more pronounced within the detection range over the 10" coil.


So.. do your final testing in the ground..


HH
Don

9" - Coil #3 for Surf PI.

[taliesin]

Good choice on size! I have settled on a 9" coil, 19t with teflon coated, 7 strand 22 AGW silver coated wire. But for all practical purposes, magnet wire works OK if you are careful not to damage the enamel insulation.

Now, here's an observation I made yesterday:

The soil where I live is sort of a clay mix.
In my test garden, I have 11 buried .58 cal Min balls, from 1" to 11".
I made sure that the ground was "clean" from any other targets before I buried them.

With my IB detectors, (Nautilus, Shadow X5, Tesoro Cibola, and White's XLT and TGSL the deepest that I can detect in the ground is only 7". Air test are probably 12" - 13" at best with the Nautilus. Going to all metal mode, a little deeper, but not much.
so, I can safely state that I loose a little under 1/2 of my depth in the ground.

Now, here is where things get interesting.. With the Surf PI and a 20us delay, I can only pick up the Minie ball at 8" in the air. In the ground, I can pick up the last Minie ball at 11"! Just barely, but it's there..

To double check, I repeated my test in another area, same thing! Then, I opened a hole and put nothing in it just to make sure that disturbed ground wasn't causing a false indication. ( I actually planted my targets by driving a pole into the ground and dropping the bullets to the bottom). I have read other places that PI detectors can go deeper in the ground, and now I believe it!!

Another reason I like the 9" coil is that targets are a little more pronounced within the detection range over the 10" coil.




So.. do your final testing in the ground..


HH
Don

9" - Coil #3 for Surf PI.

thanks Don for that info.wow i like that deeper in the ground results part.what going on there then.i shall be making a test plot in the garden soon something similar to yours.nice idea with the pole to bury the targets.
regards
tal

[plumabob]

Nice in ground test Don,

I guess thats why at the beach you dig tiny iron crap at ridiculous depths...

Bob