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Qiaozhi Thanks for the info! I was not aware the Minipulse Plus had a two stage pre-amp. I guess I need to look at the schematics and read the description of the build. I still need to get down to less than 10us in order to detect small gold and that is one of the reasons I am closely following the Chance PI. I don't have any experience programing the Atmega328 but that should not be any different than programming other pics except I will have to learn to use avrdude. I will take your advice and follow up with KRinAZ mod.
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You could calibrate the Mirage to sample down to 8us.
But, the intent was to make a very small gold jewelry detector mainly for beach hunting with as much depth as possible.
When I calibrate the Mirage at min. pulse delay for a gold nugget of 12 grains to about 4-5" depending upon search coil. At that point it will pick up a 3.2 grain nugget at about 1 to 1 1/2" from the coil.
I know my friend has his pick up a 1.5 grain gold nugget under 1" of black sand. I was going to set up a Mirage for Micro jewelry for another fellow when I got around to experimenting again.
The Mini-Pulse has a lot of potential, like George says, you may want to look at it. Right now that might be your best option.Comment
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Thanks Sven and George for your recommendations, much appreciated! I'm going ahead and order the MPP from Andy (Silverdog) and follow KRinAZ steps to get down to around 6us delay. I'm going to start building a basket weave 8" coil to try it out with the SM Pro and the MPP as soon as I finish it. Right now I have two coils I've built a 300uH 8 inch and 340uH 11inch besides my 6" Razorback which is also @ 300uH. I'll report back as soon as I build the MPP and text it with the different coils.
Thanks for your help!Comment
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Originally posted by hecbom View Post
I also have built the MPP (x2) and also use a 6x10 razorback long reach, it works excellent with the mpp and I can sample to 6us. It air tests an 8 gr (.45g) nugget at 2 inch with the delay set to 8us. My original coil, a spider (3dss according to some) at 7.5in/312uH with 250/45 litz, it works almost the same as my razorback, 1-3/4" on the 8gr nugget. I believe my razorback is 300uH as well with shielding, it was designed and made for the whites TDI.
My mirage can be set to 8us as well and with a 7inch 300uH coil (litz or Teflon 600v 26/awg) works almost as well.
You will be happy with either one but the MPP has just a tad bit more capability as far as mods go, KRinAZ (Kyle from Arizona) did a great job with the mods for gold.Comment
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hebcom, I have an ebay Tacoma56 SMpro DD. Not sure if his still come set up for DD, but with a 10x5 MLcommander (DD) coil I get 4+ inches on a 1.7g flour gold sample, air test on lowest delay. Other things worth trying would be the VSAT mod here, and maybe adjusting appropriate components related to delay.
I have the GMT too, and, yes, there are only certain spots here it can cope. But it will find the super-smalls there.
geocash this is what I would call a spider coil. There is an article here somewhere regarding Mike Tuggle's "spider"coil. They too have great potential for a fast coil.
My MPP and Chance boards from Silverdog are on the shelf while I finish my Cert II Horticulture.Comment
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All thanks and appreciation to Mr. Seven received today electronic components and successfully plan my friend now detector Mirage in Alexandria
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God to hear everything has arrived!!
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I can recommend Sven´s Mirage Pi.
With first Version i was able to detect an 1€ coin at 30cm in air with 20cm monocoil.
It is also able to detect small pieces of metal like nuggets.
But the biggest problem i had here in Germany around my search area of Berlin and east direction are the big amounts of military finds.
I found no gold but pieces of weapons, ammo, melted aluminium from ww2 airplanes, and shrapnels - i throw in next river or lake.
At beach or anywhere else with no civilzation this type of detectors will be very usefull.Comment
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KLIPCETO ???recording
where is ??Comment
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Please Seven What are the dimensions of Control BoxAnd I did not find in the shipment box on this resistance variable keys
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That control box and others I use are extremely tight. Almost not enough room. They can be a challenge for most to assemble. Careful consideration regarding control placement and assembly order is needed.
I would advise against using simlar small size boxes.
The best box where everything fits nicely including a 8 cell AA battery holder are these which I also use, I buy off ebay from this seller: http://www.ebay.com/itm/131876087763?_trksid=p2057872.m2749.l2649&ssPageNa me=STRK%3AMEBIDX%3AIT
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Rack case can be also used from old external hdd, i have this one for example:
http://17c4dcd7f91259d8cc66-f5932f6d...21-752x493.jpgComment
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I have used a couple different cases for the mirage ( see pics below).. the best fit so far has been the one below in the ebay link or "mirage 1" build and it is relatively cheap compared to other cases. its a nice case for the price too. Just spend some time on your layout before drilling and you'll be fine.
mirage 1 - inside
mirage 1 - front panel
mirage 1 - rear panel
Mirage 2 - front panel
Mirage 2 - completed (difficult case, solid one piece, only removable ends)
Case for mirage 1 build on ebay
http://www.ebay.com/itm/Black-Alumin...UAAOSwqu9U6WWV
Also used this one for a minipulse plus, excellent as well, little more pricey but good.
http://www.ebay.com/itm/330980181731...%3AMEBIDX%3AITComment
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I would be interested in 2 pcb's if you still have them available.Comment
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