large coil PI detectors

[TheGreenBoy]

Large coil has 3 ohm of ohmic resistance and 600 uH of inductivity, smaller one is 2.5 ohm and 620 uH. The circuit is tunned with large coil.
Well, a fair PI is still quite expencive in my naighborhood, so mine is home made along with the coils, so they are both original as fare as it goes - i guess.

 

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[XLV]

as what i seen different companies all used different specs ...minelab i think was 300 uh chinese clone 400 uh your are 600uh +- 10% ....as what i seen with a few different models they all give different depth readings on the same size object i have to do more research to better understand y ..stevemc i think uses garrett which seems to go deeper then the ones ive seen but florida sand not like iron sand so theres so many factors involved...AARC was florida sand also ...thanks greenboy for your help

 

[TheGreenBoy]

There is no direct coleration between inductivity of the coil and performance of detector. The coil must match the machine consisting the tunned part of the circuit. Coils with lower inductivity are deemed to be faster and produce weeker magnetic field at the same current. However, the magnetic density (strenght) depends on energy the coil is powered with, the discharging speed depends on dumping shant resistor as well. The speed of field forming is directly colerated with coil inductivity, but this is usually not critical if the pulse rate frequency is keept low enought. The two other values, ohmic resistance and capacitance are both parasitic and should be keept as low as possible.

 

[XLV]

what u said is what i also heard the other factor i notice minelab coils are smaller for there models and might be faster for there intent large nugget targets ,,,my machine probably designed around the 20 inch size ..and yours is probably designed for 40 or bigger very large target i could be wrong about this if i remember right most coin machines are 300 ....since u know 100x more then i do how much does the type of sand play in depth because everything i read dosn't match what the florida boys say where am at its iron sand and hot rocks ...or maybe its designed for smaller targets then there models

 

[XLV]

I figured i start with a 36" stand on a plastic sled made out of 4' drain pipe i try this on the beach wet and dry sand with my soda can (under 2"of sand ) and my 20 kilo nickel bronze target ( under 2 feet of sand ) remember am only interested in the top 2 feet on the wet beach

 

[XLV]

The funny thing after going over what ive tested and found in the past i might need a smaller coil 16x16 for the wet beach ,,,,im guessing upland 40 dry beach 20 wet beach 16 in the sea 12 ...i have to give this some more thought

 

[TheGreenBoy]

Well designed PI shoulden't have much problems with salti and mineralized soils and should give you more depth one is willing to dig. Any soil always takes some depth away, the only exception i have seen are PIs with exstreme energy pulses, powering those is another story, though. But if you use anythig usual, such as XR71, DBP2010, Pulse star, or similar detector, you shulden't have much problems.

 

[XLV]

Thanks again Greenboy ...am flag stupid where do u search old ww2 sites in euro ...where am its illegal to look upland without a permit ....tourist are beach only here ...i guess no uxb on the beach here thats the reason i heard ... good luck with your hunts

 

[TheGreenBoy]

Thanks MDCLXVI. The legal aspect is quite complex in my country. Simplified, one can search anywhere where is not forbiden (there is a map resembling the Swiss chesse) as long as he or she doesn't find anything.....