CHANCE PI CIRCUIT DIAGRAM NEEDED

[daverave]

Hi my friend i have a new pcb and change the etc

hello
have you inproved the original pcb design...is yours improved....i have not made mine as yet cause been too busy with other projects....i did look at the chance pi detector on youtube and i noticed the audio response chirps like a bird instead of nice clean threshold....did you have this problem ???

[sinclairuser]

has the code problem been solved with the chance?.

[Bardia]

New

Hi the new pcb is bathr as main sartainly and upload the film in there or youtube as soon as

[daverave]

Hi the new pcb is bathr as main sartainly and upload the film in there or youtube as soon as

what is the youtube link pls

[Waikiki_Sweep]

I am interesting to buy Chance PCB too. Unfortunately I was late to get it from silverdog. Chance is probably my last hope to get a PI machine with target identification build. I have read original ML patent which used for Chance design and suspect that major problem of Chance that it was build with monocoil. You can see a balanced TX/RX coil in original idea. As result target identification less stable and targets orientation messing up identification results. (I think.)

[baum7154]

The code problems I am familiar with are in versions predating V1.2.1. If you use the V1.2.1 the detector operates as it was intended. Discrimination for small gold is plagued in the field by many small bits of aluminum in my experience.

Regards,

Dan

[baum7154]

Below is a repost from the COILS forum of performance of this detector using an 8" fast spiderwound coil:

Coil damping

Tested detector with 1110 ohm coil damping on 1/2' target tonight over wet grass and saw no degradation in signal strength from last night's test over wet grass. Got the same 8 signal strength units at maximum proximity to target. Coil is 8" diameter.

Other targets were tested in air in the basement as follows:
TARGET DISTANCE
1 sq in x .001" thick aluminum foil 9.5"

1/2 sq in Aluminum foil 8"

1/4 sq in Alum foil 7"

1 cm sq Alum foil 4"

US Nickel 12"

US copper Penny 9"

US silver dime 7"

10.5 grain dental gold 6"

8.4 grain dental gold 4"

---------------------------------------

I will be posting pictures of this CHANCE detector soon.

Dan

[daverave]

are you saying that to get good target id with chance you have to use 2 coils balanced like a 2D vlf coil ???? cause one of my future projects is to make the chance pi which seems very interesting....can it reject iron ????

[baum7154]

First of all I built CHANCE with the objective to find small (5 to 15 grain) placer nuggets in old dredge piles. As a result my focus has been on speed in the coil and yes, the ability to give SOME indication of what a target might be. That said CHANCE definitely shows iron at the right end of its discrimination scale and gold AND aluminum at the left end. CHANCE does have 4 selections for Masking out iron and they are NONE, MASK1, MASK2, and MASK3. Unfortunately increasing the MASK value does have the consequence of some reduced sensitivity for gold. MASK1 is pretty good but MASK3 is noticeably less sensitive. The other thing is that a large piece 8oz of iron will have enough return signal to bulldoze through the MASK and trigger the detector. I generally don't use the MASK function but if I do it is MASK1. The VDI display is what I rely on. Aluminum has proven to be my biggest problem in searching for gold. Anything from broken down can bits to aluminized plastic juice packets trigger this detector when it is running wide open.

[Waikiki_Sweep]

are you saying that to get good target id with chance you have to use 2 coils balanced like a 2D vlf coil ???? cause one of my future projects is to make the chance pi which seems very interesting....can it reject iron ????

Sure it rejects iron. And even gives different sound and readings for target identification.

Andy_F has created a Chance MD to test of ability of PI detector to identify targets by the way as it described in ML patent US5506506.
And it works, but result are not good for targets in different orientation like if coin stays on edge. I heard it on his forum.
Also once it mentioned on geotech forum that you need separated RX/TX coils to get correct reading of target conductance.
Also I can see that same US5506506 technology is used in huge line of ML detectors like eXplorer, Excalibur, Sovereign, CTX3030, e.t.c.
And they all able to identify targets very precise and all they has separate TX/RX coils.

So my conclusion is. Chance needs separate balanced TX/RX coil pair to be as good as ML detectors in targets identification.

But even if you will hook balanced coil on it there is no chance it will work properly because changes to software sure will be required.
And such changes can make only author Andy_F who keeps source codes. Probably you can ask him. What if it will work.


> Discrimination for small gold is plagued in the field by many small bits of aluminum in my experience.

Gold and aluminum has almost the same conductance. I do not think it is possible to separate it with any metal detector.
Once you start to discriminate small aluminum pieces you will lose small gold items or nuggets.

.

[6666]

As there is a fair bit of interest in the chance project, I wonder what chance there is of Silverdog doing a few more pcb's ?

[Waikiki_Sweep]

As there is a fair bit of interest in the chance project, I wonder what chance there is of Silverdog doing a few more pcb's ?

I am first in the line! OK?

[baum7154]

My coil is a spider wound monocoil 8" in dia. You can find the construction details in the COILS forum. Basically it uses 26AWG teflon insulated wire wound on a machined polycarbonate slotted toroidal form with NO SOLDER anywhere in the coil and the feed line is a continuation of the coil wire twisted at a rate of 3 twists per inch. Very low capacitance.

Dan

[bernte_one]

hello bardia

can you post a picture of your new pcb design here?

[baum7154]

Sure it rejects iron. And even gives different sound and readings for target identification.

Andy_F has created a Chance MD to test of ability of PI detector to identify targets by the way as it described in ML patent US5506506.
And it works, but result are not good for targets in different orientation like if coin stays on edge. I heard it on his forum.
Also once it mentioned on geotech forum that you need separated RX/TX coils to get correct reading of target conductance.
Also I can see that same US5506506 technology is used in huge line of ML detectors like eXplorer, Excalibur, Sovereign, CTX3030, e.t.c.
And they all able to identify targets very precise and all they has separate TX/RX coils.

So my conclusion is. Chance needs separate balanced TX/RX coil pair to be as good as ML detectors in targets identification.

But even if you will hook balanced coil on it there is no chance it will work properly because changes to software sure will be required.
And such changes can make only author Andy_F who keeps source codes.

.

Yes the different audio sounds , lowest for Gold/aluminum highest for silver, iron etc. is very useful. However my hearing has some difficulty with the very high frequency for silver. By the way CHANCE also has a very low raspy tone to indicate full RX signal saturation that should not be confused with the low tone for gold/aluminum. The tones are different and recognizable.

Do not all detectors have different responses to the same targets in different orientations? For example a gold ring parallel vs. edge on to a coil?

Using a separate tx/rx coil would also require hardware changes to the PCB to make the most of it, in addition to the software changes already mentioned. Would be interesting to do!

By the way, the original search coil on F_Andy site was a coaxial monocoil of 400uh and 1.7 ohms and it was stated that the detector must use this coil and it's 390 ohm damping resistor. It proved to be too slow for small gold and never could reach the minimum Guard Interval of 10 as designed. The best the original coil did was a GI of 23. This set me off to create a more effective coil/feed line that was fast enough for small gold. Also the 390 ohm damping resistor was changed to about 1150 ohms and made a huge difference in getting to the desired Guard Interval setting of 10. The current 8" coil will see a 4.5 grain piece of 14K gold at 1.75"...not very deep but it does see it. This same coil will see a 128 grain gold nugget at 9.5" in air.

Dan