Arduino Nano PI Main Discussion

[6666]

If anybody in Australia is interested I have ordered some nano PCB's and have two spare
if you want to put your name on one pm me,

[6666]

Thanks George. I'll try an ABS enclosure then for the Arduino project first. Thanks also for the advice on the Crossbow, I was looking for info on that too. I should have my Arduino detector ready to test by the weekend if the 2 components I need arrive. Thanks again, Marty.

Copper tape inside an ABS box works ok.

[MartyJ1963]

Thanks George. I'll try an ABS enclosure then for the Arduino project first. Thanks also for the advice on the Crossbow, I was looking for info on that too. I should have my Arduino detector ready to test by the weekend if the 2 components I need arrive. Thanks again, Marty.

[Qiaozhi]

In a handheld detector the alternative is to make sure the mains frequency aliases outside the target filter bandwidth. This is usually set by the demod and the Nano has a BW = 1.5Hz (which is pretty low). Assuming 50Hz mains, if you set the detector to 1200Hz then the alias is synchronous and becomes a DC offset. But if the mains drifts by 0.1% then the alias is at 1201.2Hz and you hear a 1.2Hz beat frequency. However, if you set the detector to 1225 Hz then the 50Hz alias is at 25Hz which is suppressed by the target filter BW. And any minor mains variation remains suppressed. BTW, the demod is often followed by additional filtering that roughly matches the demod BW to offer better mains suppression. In the Nano, this would be R26-C15... setting them to 1.5Hz will help (they are currently 16Hz).

Interesting ...
The values used by the Nano are the same as those for Surf-PI. I hadn't noticed the difference in cut-off frequency between the two opamp stages, so I'll try changing C15 to 1uF, and setting the detector to 1225pps. Then I'll report back here with the results.

[Qiaozhi]

Hiya George, hope you're well. Did you have to shield the ABS plastic enclosure for your Arduino detector? I'm stuck whether to get an Aluminium enclosure or an ABS one,,,which one is best to use please? Regards, Marty.

Hi Marty,

I didn't shield the enclosure, and it seems to be fine.
In the past I was convinced that a metal enclosure was almost mandatory to eliminate any external noise, but it doesn't always seem to be necessary in practice. With Crossbow I used an extruded aluminium case, and did notice that it was important to make sure the shield from the coil cable made a good electrical connection to the coil plug casing, otherwise the audio was less stable. The only problem with a metal enclosure is that the detector can become quite heavy.
It would be interesting to get opinions from other members on this subject.

[MartyJ1963]

Hiya George, hope you're well. Did you have to shield the ABS plastic enclosure for your Arduino detector? I'm stuck whether to get an Aluminium enclosure or an ABS one,,,which one is best to use please? Regards, Marty.

[green]

Charted ground decay(change in integrator out)vs target delay time, 10us target sample. Can detect a 1 to 2mV change at integrator out on the bench.

Looked at chart log-log this morning. Different slope than I expected. Charted ground decay with Excel, amplifier out and integrator out(delay+10us). Looks similar to what I measured this morning. My math skills are lacking, maybe someone could explain why integrator out decay is a lot slower than amplifier out.

[green]

I use all four. target sample(N) ground sample(I) then target sample(I) ground sample(N)for EFE

Including a decay chart for 10x10mm foil and the 4grain nugget I have tested at 1inch. integrator out vs delay time

The 6x7x1 inch zip lock bag of dirt from California saturates the integrator(>2.5V)when positioned over one of the fig8 Rx coils with a 6us delay. 10 on the chart is 1mV

Charted ground decay(change in integrator out)vs target delay time, 10us target sample. Can detect a 1 to 2mV change at integrator out on the bench.

[Qiaozhi]

Has anyone made a BOM besides the one in the book?

I think he likes to physically check things off as they are installed but doesn't want to mark up his book.

OK - that makes sense.
Bernte_one ... PDF sent by email.

[green]

Hi Green,

On your Gb are you using three of 4 samples.
I had good results with the 4 sample method first sample at 5 us. I would have to go back and put that board back together to find my timings I Lost my notes for now.
One thing I never got it into the field to try but on my bench it almost seemed to perform better than without GB.
I think that the 4th sample was helping to reduce noise in test area.

I recently found a area where ground balance was almost unusable while testing the vallon detector. The vallon coil could barley cope a smaller coil was able to hunt in Gb mode at way reduced depth.

[ATTACH]54856[/ATTACH]

Testing the sand fallen off targets in my pouch with magnet there was 25 % magnetite by weight.
Point is Gb didn't work here and I was able to hunt in regular mode.

I think anything under 5 us is not going to be usable in the field and 5 would be only in super mild soils not the gold fields around here. Maybe if the gb is super dialed in.
but having the ability to sample that low could be a valuable tool looking for small jewelry on a clean milder beach type sand.

Setting a goal if you want to nugget hunt and could recreate the performance of a Tdi with a high quality coil as yours you could be competitive out there at ten us I was thinking 8 us might be really pushing it in the gold fields. here you would even get cold rocks at that Low Ill bet on it as my old sand shark would pick them up.

I use all four. target sample(N) ground sample(I) then target sample(I) ground sample(N)for EFE

Including a decay chart for 10x10mm foil and the 4grain nugget I have tested at 1inch. integrator out vs delay time

The 6x7x1 inch zip lock bag of dirt from California saturates the integrator(>2.5V)when positioned over one of the fig8 Rx coils with a 6us delay. 10 on the chart is 1mV

[Carl-NC]

What's wrong with the Component Parts List in the book?

I think he likes to physically check things off as they are installed but doesn't want to mark up his book.

[godigit1]

I was just rethinking what it meant to be competitive in the gold fields around here.
you need the best machine a motorhome a month to scour the area. Your competition full blown geologists out there like Nv chris and uber miners like Steve Hershbach and to top it off they team up with people like Digger bob and you better be good to follow behind them and hope to find anything.

Inland prospecting Jewelry I find way more gold because of lack of time to spend in the field. 4 hunts over 150 in gold so far this year.
Vallon is almost half paid for.
Sorry for going off track but the reality of prospecting for gold is that if you have the time and are going to spend allot of money to get out there you better have the best tool in your hands you can even if you have to rent it you might get lucky.

Ps The sand in the photo is from the same beach as in my avatar photo. just saying.

[godigit1]

Hi Green,

On your Gb are you using three of 4 samples.
I had good results with the 4 sample method first sample at 5 us. I would have to go back and put that board back together to find my timings I Lost my notes for now.
One thing I never got it into the field to try but on my bench it almost seemed to perform better than without GB.
I think that the 4th sample was helping to reduce noise in test area.

I recently found a area where ground balance was almost unusable while testing the vallon detector. The vallon coil could barley cope a smaller coil was able to hunt in Gb mode at way reduced depth.



Testing the sand fallen off targets in my pouch with magnet there was 25 % magnetite by weight.
Point is Gb didn't work here and I was able to hunt in regular mode.

I think anything under 5 us is not going to be usable in the field and 5 would be only in super mild soils not the gold fields around here. Maybe if the gb is super dialed in.
but having the ability to sample that low could be a valuable tool looking for small jewelry on a clean milder beach type sand.

Setting a goal if you want to nugget hunt and could recreate the performance of a Tdi with a high quality coil as yours you could be competitive out there at ten us I was thinking 8 us might be really pushing it in the gold fields. here you would even get cold rocks at that Low Ill bet on it as my old sand shark would pick them up.

[Qiaozhi]

Has anyone made a BOM besides the one in the book?

What's wrong with the Component Parts List in the book?

[bernte_one]

Has anyone made a BOM besides the one in the book?