Barracuda rev2

[Tibuck19]

Good morning folks, Could you guys tell what coil induction you found works best with Cuda REV2. my coil size is a 200 mm that formed in to a elliptical shape, pretty much all Canadian clad I can detect a good 10 to 12 inches away but when it comes to American coins, it drops to about 6 to 8 inches ( 8" being a quarter). Perhaps a circle is better shape for a search coil with this MD ? Any thoughts are appreciated. Kit came from Andy at silverdog.
Thanks

[Koala]

Good morning folks, Could you guys tell what coil induction you found works best with Cuda REV2. my coil size is a 200 mm that formed in to a elliptical shape, pretty much all Canadian clad I can detect a good 10 to 12 inches away but when it comes to American coins, it drops to about 6 to 8 inches ( 8" being a quarter). Perhaps a circle is better shape for a search coil with this MD ? Any thoughts are appreciated. Kit came from Andy at silverdog.
Thanks

I tried several shapes. Triangle, rectangle, square, ellipse and circle. Best for performance and pinpointing is the circle. Although I can see the advantage of a triangle around rocks.



1R5 and 450uH is what I aimed for.

9" out of .5mm enamelled copper wire is where I finished up if I remember correctly.

Delay is a compromise. Best average depth does not give you any iron discrimination. Best gold depth gives very poor depth on dome copper alloys.

[homefire]

300 - 400uH / 1.5 Ohms will work fine for you.

[Tibuck19]

thank you for the response guys, and keep them coming knowledge is power, just wounded a new one this evening same shape 288uH 1.5OHMs and now I have gained two inches on the American clad about the same for the Canadian coins , A small gold necklace piece of 10mmx8mm 1mm thick I can pick up at 8" how does that compare to your coil?

[Koala]

http://www.geotech1.com/forums/attac...0&d=1459631333

[Tibuck19]

Thank you for the death chart , very useful, I am assuming you made a slower delay coil ?

[Koala]

Yes coil on post 2


Best compromise on the delay I could find. I can get several more inches on the gold ring centre of photo but loose half the depth on the fibula middle row right.


Bottom right coin is a Canadian copper nickel can't remember its value about 18mm

[Tibuck19]

Do you use a volt meter to set the value of the delay ? If so what pin on what ic is it? I use pin 7 on the, 5534 to set the coil to zero, but have not pokes around to find the one for the delay, been setting it by ear. Canadian clad rights load and clear for me as-well. I have a good stock od 0.40mm wire, I ll wind one with a 450uH just for kicks to see the difference is.

[Koala]

Nope delay set by trial and error. Different delays are better for different targets. Got a selection of finds and tested each until I got a nice compromise. If I remember correctly the gold ring goes up to 14" but useless on other targets

450 is what the original damping resistor is for.


Offset i set to 0V on an oscilloscope.

[Tibuck19]

I pretty much settled on 0.4547 wire for my 6"x10" coil, giving me a 291 uH , Canadian and American quarters at 13inch CAD and 11.5inch USD, nickels and dames at 8.5, that little gold peace at little over 7 inches. I ll have to go ask a lady for a gold and sliver ring to test those at, Also I have a 1906 V nickel it comes in at 6 inches. you think better could be done ?

[Koala]

8" on small coins with a 6" wide coil is very good. Doubt there anything to be gained.

[Tibuck19]

I do have a small problem, seems im getting beeps when im swinging the coil, I was sure I read somewhere that slow coils don't need shielding, but from what I am seeing that might be false, I tried the silly thing of wrapping Aluminum foil hahahaha what a waste of time, Now I read, some use copper tape , I even read graphite could help, What do you think the problem is?? is it just a matter of better adjusting the pots for the delay speed or do I really have a shielding issue I need to address ?Im considering buying graphite and mixing it heavily with my polyurethane when I pour my cavity in the coil housing, What do you thing? oh and I also tried the Nashua tape I lost all coil sensitivity.

[Qiaozhi]

I do have a small problem, seems im getting beeps when im swinging the coil, I was sure I read somewhere that slow coils don't need shielding, but from what I am seeing that might be false, I tried the silly thing of wrapping Aluminum foil hahahaha what a waste of time, Now I read, some use copper tape , I even read graphite could help, What do you think the problem is?? is it just a matter of better adjusting the pots for the delay speed or do I really have a shielding issue I need to address ?Im considering buying graphite and mixing it heavily with my polyurethane when I pour my cavity in the coil housing, What do you thing? oh and I also tried the Nashua tape I lost all coil sensitivity.

Try an air test where you wave a small magnet about 3 to 4 inches from the coil. Does it beep then?

[Tibuck19]

Good morning, Yes it beeps , not the same as a coin it has a weaker double beep, Maybe it the wire to the unit ? this is the cable I used http://www.cercocable.com/products/d...ew.php?p=19170

[Qiaozhi]

Good morning, Yes it beeps , not the same as a coin it has a weaker double beep, Maybe it the wire to the unit ? this is the cable I used http://www.cercocable.com/products/d...ew.php?p=19170

If it beeps with the magnet, then the Earth Field is not being eliminated properly. Using a scope, check that the EF pulse is located at the correct time, and has the same width as the main sample pulse.