IRF 9640 QUESTION

[Davor]

VLF measures ferrous that way all the time.
There is a reasonable enough method within PI to discriminate various types of metal and have GB at the same time. Only trouble is that PI suffers more from thickness related influences than narrow band VLF, so discrimination will always remain soggy. Without proper measurement of permeability there is no proper ferrous discrimination either. I'll try some of these tricks ... eventually.

[daverave]

i remember many years ago a british detector called a ground hawk pulse induction which had iron discrimination using pi and bfo together which looked very interesting but never heard of now !!!!

[kt315]

yes I remember somebody wrote about the ground hawk...

Operating Frequency vs Depth

Joined: 19 May 2005
Posts: 25
Location: USA
Posted: Fri Jul 29, 2005 8:07 pm

I found this comment at White's website in their FAQ section:

As a rule, lower frequency detectors offer better sensitivity to copper and silver and better overall detection depth and trash rejection. Most general purpose models operate at lower frequencies.

Higher frequency detectors are more sensitive to small metals and natural gold. However, they have difficulties with discrimination against nonferrous (not-of-iron) metals. Their sensitivity to small metals makes them tedious to use around trashy areas. Most gold prospecting detectors operate at higher frequencies."

Hope this helps.

Many years ago a detector was produced in the UK call GROUNDHAWK. It was a combination of a PI and a BFO. You had to switch between one mode and the other, but it was quite popular with land detectorist for identifying iron. The BFO mode, obviously did not have the range of the PI mode, but it was still useful. A PI mono coil is very compatible with a BFO circuit.

[daverave]

Hello kt315......can a bfo detector be used on dry and wet sand ???

[kt315]

hi Dave. can but bfo ideology has died. they are unstable in work. I do not keep and not collect bfo schematics, its all riped...

[daverave]

ok thanks kt315