New Zealand Gold Prospecting & Metal Detecting Forums Archive

#36 trip. the site 8. Its just gettin better and better now. Was just about had enough with small coin after coin when i found a japanese coin on a string knecklace with a small piece of stone attached. Now this is wot i call the find of the month. Well for me anyhow. (Maybe not, the 1854 penny token was pretty cool.) Soon as i seen it i stopped digging, went to the van and got my hand trowel and a plastic bag and the camera. Went back casualy as not to create attention and carefully excavated the find. Yeha. Now that makes 1 piece of jewelly per say too every 13 coins found. Aprox. Attracting attention anyway down there. People walking up to me now and interested in wot im doin. A friend stopped for a howdy, and another guy heard i was there and came by with his detector, we plan to hook up for a hunt. he seemed very keen. Wot a day was real cool. 1 goldie, 11 coins all up and a coin knecklace. (Which makes it 12 coins.)

12 coins


Just about to go home and ding ding... A proud moment for the ace.


The find. Nylon chord with a hollow center coin added. Been hit with a mower, just, id say.


Shane

Edited by user Tuesday, 1 November 2011 9:41:36 AM(UTC)  | Reason: Not specified

You are doing well at that site Shane! Nice chunk of greenstone there.

With the sensitivity of the detector maxed out you don't loose depth as such but you will get a lot more interference. The detector will "hear" everything instead of just the target signals. This means the poor little brain of the detector is trying to work out what is ground mineralisation, EMI (from power lines, houses etc) and that gold ring 10" down. Because it is hearing everything it will only try to report (sound off in the headphones) the strongest signals it gets and chances are a target will not be the strongest signal. Your detector may not be falsifying or sounding off too much but the brain of it could still be tuning out the targets because it is confusing them with the interference.

Liken it to being at a party. Your friends voice may be distinctive and recognisable to you but with all the other noise going on picking that one voice from the crowd is near impossible. The detector is made to tune out all the other voices and listen in on your friends but the louder the volume the less it is able to do this (unless your mate is close to you which is the same as a shallow target).

With the higher end detectors you can adjust this or that setting to reduce interference before turning down the sensitivity but in most situations the receiver gain from the coil still has to be turned down. For example I don't believe my V3i reaches any deeper then my AT Pro (which is close to your 350) but because I can tune the settings more it can identify the deep targets better.

Turning the sensitivity down will not reach deeper but it will mean the detector hears less of the interference around you and be able to id a signal as a target better.

This is also the reason why the lead registered as iron. The deeper the target is the less signal the detector has to work on and the less sure it will be in the id'ing of it from all the background "noise". I find that the deeper the target is the lower the VDI will be for it, this is the same for both of my detectors.

With the AT Pro I normally hunt on the beach with one notch removed from the sensitivity and when on land - 2 or 3 notches removed. This seems to work in picking up and id'ing the target better then if it was maxed out.

Also with the Garret detectors the sensitivity is not linear, if you graphed it out it would be more like a curve. In other words turning the sensitivity down to the half way mark (4 notches removed) does not mean you will only get 50% the maximum depth. Instead you will still get something like 75% of the depth. With it 3/4 of the way (2 notches removed) you still getting something around the 95% of the maximum depth. Thus turning it down by one or 2 notches doesn't make much difference to the depth. BUT it can make a large difference in picking up interference and mineralisation.

Hope this helps. I haven't been out hunting for a while and am suffering from withdrawal symptoms. Currently waiting for the invasion of Aucklander's to disappear off the island so I can find all the stuff they have left behind!

The AT in pro mode uses sound for similar accuracy. If it is a clean clear tone then it will be a coin or ring etc, if there is any breakup in the tone it is normally junk. The V3i has a range of methods - in the spectragraph the bars representing the 3 frequencies will be all in a line and of similar colour if it is a good target, but all over the place if junk. In the polar plot it will graph out the 3 frequencies and if the lines are in the upper quadrant and straight then it will be a good find. The more confident the machine is of its findings the more uniform the graphs will be - if it is unsure the graphs start to break up and look messy.

But with both detectors (and I am assuming other makes as well) this level of accuracy will reduce with the depth of a target. For example the polar plot on the V3i is only good to 15cm after that it becomes unreliable to use so I only use it with my Goldie program where shallow $1 & $2's are the only things not discriminated out. The spectragraph is better and works down to around 25cm but is not as accurate in id'ing (it will show a V bottle cap as a coin which the polar plot won't).

The deeper the target the less reliable any dectector id becomes. Thus if a target is shallow and the detector is telling me it is junk then it will be and I won't dig. But if the target is deep and the detector is saying "junk" then I won't believe it and dig anyway. Sometimes it will be a piece of iron but surprisingly often it is a nice coin or ring.

I haven't used a Fisher but assume it will be the same. Thus if it was telling me that it was confident in its id of junk but the target was a deep one - I would still dig. I seem to find most deep targets are good finds anyway since they are normally older and from a time before pull tab and screw tops etc were around.

Edited by user Monday, 24 October 2011 8:41:02 AM(UTC)  | Reason: Not specified

Yip, a japanese yen. Awesome find i cant believe it. This spot is about to finish. Well i want to finish it up for now, its to intense. A couple more cricket sized pitch runs and thats it for now. over the actual buildings in the corner. And yes we do have a fair bit of history there ourselves. Running the hostel, the common room, (we called it the love hotel...) the english guys who were insane on fishing, the missions, awesome place. Now its bulldozed...Ah well memories are cool. I wonder if we dropped any of the coins there. Probably. I only have one original pik of the place but i cant find it yet.

Bro

Edited by user Tuesday, 1 November 2011 9:43:13 AM(UTC)  | Reason: Not specified

Your on to it there bro, thats how you find the cool stuff. The yha site would be a hard one tho. Its doin/done my head in from 8 attempts. Even with the discriminator its very hard goin in some spots. So much iron/metal its amazing. Anyhow, Puhi puhi mines on thurs/friday.

---

loot...

The loot sorting department

A load of loot so far at one spot

A selection of recent finds


Shane

Edited by user Tuesday, 25 October 2011 5:30:37 PM(UTC)  | Reason: Not specified

I tried to post this once already but since it isn’t here I guess I botched it, if this is a repeat I apologize:

Shilo,

Yes my Fisher behaves similarly, deeper targets make for poorer signals and I dig them all. As you said with trashy targets the computer can’t make up its mind and bounces around and won’t settle down.

Something I learned (and I am still learning) is to use all the information available. In my case that is the audio, the digital readout (which is a separate process than the audio), the confidence, and the depth. Put all those together and sweep from different angles and you get the best guess at the target. Oh, and I will swing the detector higher and higher in the air over the target until I lose it. If it keeps reading way up in the air the object is huge (like a can) and I don’t believe the high reading the detector is giving.

Another thing I learned to do is to really pinpoint the target before digging. Saves work and avoids damaging valuable treasures.

Back on the subject of interference, something I forgot to mention is that my detector has different programs that effect how the computer interprets targets. For example there is a jewellery setting, a bottle cap setting etc. Monday I was having a lot of trouble with interference and after trying all the tricks mentioned earlier I simply switched to ‘bottle cap’ mode and that cleaned things up nicely. I assume because it is a less sensitive program.

I would not swear the bottle cap program was the solution; I am not sure what it is about this park, but the interference is really bad in some areas and not so bad in others. Underground power wires? So it might have been that I switched as I was wandering out of the interference area.

Our two machines sound fairly similar in how they operate. I was using a Gold Bug and was quite happy with it but tried the F75 and immediately fell in love with it. It costs twice as much as the Gold Bug, and I wouldn’t say it is twice as good (Poohbear detected circles around me a couple weeks ago at Tonz beach spot), but it is better at discrimination. I don’t think I am finding anything I wouldn’t have found with the Gold Bug or any other decent detector, but I dig a fraction of the junk and therefore cover more ground in a day. Monday I was out for about 4 hours, found a heap of coins, and only dug 2 or 3 bottle caps and about the same number of pull tabs. Still, I feel like I learn something every time I go out.

GOLD AT LAST
#37 trip. Great two days out with Chrisyboy. Hit a large difficult beach then ended up at a short beach where the going was good. Choice we found a Glory Lane. We hit a 925 silver ring with a very nice stone, a sterling silver pendant engraved and then half way along we found a nice small GOLD ring with a small diamond. 10k. Again that was a 10k GOLD ring. Found about 60 coins, the best being a nz 1946 threepence. We were finding 3 or 4 at a time, there were heaps. Not bad for 2 hours there.
The days finds

A small beach

Happy moment




Shane

Edited by user Sunday, 30 October 2011 10:50:34 AM(UTC)  | Reason: Not specified

Great going on the GOLD & SILVER!!!!! Yippee!!!!!
Still buzzing??? :)

Haha that made me smile creamer FINALLY you got your gold ring! well done may you get many more.