ground signal

[Ferric Toes]

Tried unipolar circuit, similar results. Larger difference at 4us delay with Alabama timings same as California timings. Cancel close when delay is 6us or greater.

Ground readings are integrator out .1mV resolution should read change in integrator out (reply#9)

I'm building a bipolar circuit to experiment with. One thing I will be looking at, is whether a hysteresis effect shows up. Magnetic soil minerals do exhibit this, albeit a very narrow loop and what is called 'wasp waisted'. Bipolar, I think, should cancel this and could result in a different reading to that of unipolar.

One other interesting effect that I have observed is with Australian ironstone. Some solid lumps have a small degree of remanent magnetisation in that a compass needle can be repelled on one pole. If the ironstone is demagnetised, then the viscosity reading increases. Left for a few hours the remanent magnetisation returns and the reading returns roughly to its original value.

EF cancellation also need to be effective for the quick jumps when the coil is scanned over such magnetised rocks.

Eric.

[6666]

schematic I use except base resistors are 1k. Think 2k might be better. Probably need IB coil, not sure why IB coil doesn't zap the amplifier.

Thanks Green much appreciated.

[6666]

One other interesting effect that I have observed is with Australian ironstone. Some solid lumps have a small degree of remanent magnetisation in that a compass needle can be repelled on one pole.

Hi Eric, just tried a compass and some hot rocks I got from Beggary Hills at Wedderburn, and depending on orientation the rocks attract or deflect the needle

[green]

Not certain what you want. For Rx, I wind two round spiral coils the same(test for inductance and resonance, calculate a Rd for each coil[1.5 to 2 times pi x L x Fr]), lay them side by side and connect the outer windings together. Inner windings are Rx coil ends. Connect the Rd resistors across each Rx coil. For Tx I wind a oval coil over Rx, about 3/16 inch space between Rx and Tx. Complete the coil. Rx coil is connected to a differential amplifier. Coil is not perfectly balanced so a ferrite core is positioned on the coil for final balance(amplifier zero output when Tx on and no target). Circuit before the integrator is the amplifier and Rx coil. Are you asking for the amplifier schematic?

Making another 200mm figure eight coil. Some pictures as I build.

[Ferric Toes]

Hi Eric, just tried a compass and some hot rocks I got from Beggary Hills at Wedderburn, and depending on orientation the rocks attract or deflect the needle

Yes, it is the deflection/repulsion that identifies remanent magnetism. That ironstone, if it had no remanent magnetism, would attract either pole of a compass in any orientation. This remanence may be the cause of a rock being labled as 'hot' if the EF circuitry does not cancel it. There are two possible causes for the remanence, one is lightning strikes and the other more likely one is that when the rock was formed, the nanoparticles settled into an alignment with the earth's magnetic field and were 'frozen' as the rock solidified. Over millions of years the rock was eroded and broken up, so that individual pieces retain that original alignment.

Eric.