Another dumb question..but you guys are used to them

[jimpeterson]

On the two box machines...Has anyone done any experiments with the coils, to, maybe widen the path, or to go deeper, etc?

[Carl-NC]

There are no dumb questions, just dumb answers. I haven't personally, but another engineer at White's did some work on this. In general, like other detectors, larger coils go deeper but lose sensitivity. Wider spacing can do this too, up to a point. We were also going to work with non-orthogonal placement, and using them for PI, but he retired and no one has picked it up yet.

[mikebg]

I experimented the three configurations shown below. The "almost orthogonal" configuration (in the middle) operates better because RX coil moves closest to ground.

[Carl-NC]

Were your experiments with IB or PI?

[Reg]

Hi Carl,

Who retired? Anyone I met?

Reg

[mikebg]

Were your experiments with IB or PI?

Both.
The VLF circuit was Tesoro - Lobo.
The PI circuit was Pulse Technology - Superscan.

[Carl-NC]

Hi Carl,

Who retired? Anyone I met?

Reg

Dan Geyer, he was lead engineer on the TDI. One reason why my PI efforts have slowed.

[Reg]

Carl,

Sorry to hear you lost your lead engineer on the PI projects. On the upside, Dan did a lot of great work and deserves a good rest. I hope he is still healthy and enjoys his retirement for many years.

Reg

[Davor]

Gee, too bad there are no international vacancies, I'd apply for sure. This metal detecting technology is addictive.

[mikebg]

The following explanation is written for Mr Jim Peterson, who believes that a coil configuration 2BOX can locate meteorite crash site at a depth of 1.5 meters.

A metal detector for meteorites should be very sensitive to two types of target:
1. "Hot rocks" because most meteorites are ferromagnetic.
2. Caves because there are meteorites that do not generate a signal at air test. When driven into the soil, they generate a signal as from the cavity, because they lack conductivity and cause local changes of GND signal. Jewelers buy these meteorites a very high price, so it pays to develop a metal detector, which creates a strong GND signal.

I tried searching for meteorites with Tesoro - Lobo because it works on two - three times higher TX frequency than conventional metal detectors and better and can suppress the third harmonic of mains frequency. However experiments showed that TX frequency must be higher than 20kHz to create more powerful GND signal from dry soil. Further, the soil acts as a core for TX coil, causing parasitic modulation of TX. To avoid this, I placed TX coil away from the earth as shown in the attached drawing.

As for the PI, to create a strong GND signal is needed fast TX circuit placed inside search head. Superscan was not suitable for this.

In general, larger meteorites have hammered deeper in the dust if they have fallen long ago. Little meteorites have driven shallow. Often, a recently fallen meteorite is not covered with earth and is visible in the bottom of his crater.

Since 2BOX can not detect small meteorites, and it is difficult pinpointing, I made TWIN LOOP RX coil as shown below. This configuration proved to be very sensitive at air test. I could not do field test with sowed twin loop RX coil because my friends were quick to take the Tesoro - Lobo and Suprscan in Ukraine and Russia to search for gold nuggets. From there I was informed that they have realized our idea to improve RX of Lobo:
a) its input to act as a low noise narrow band preamp and
b) to use the carrier recovery block instead wire connection with TX.
I managed to master TX circuit suppressing amplitude modulation to enable the TX coil to move close to the ground as in the original design of the CEIA. I hope they have seen my TX circuits in this forum and they have improved TX of Lobo.

[I will post the drawing later because I can not find it]

[WM6]

Jewelers buy these meteorites a very high price,

Hi mikebg, do you know why jewellers are interested in meteorites?

[Davor]

Does it really matter? (don't discourage them while they do)

I'm more interested how you locate the approximate meteorite fall site. By asking the locals? I can understand the metal detecting part, but I don't understand how you increase your odds of finding a meteorite in the first place

[mikebg]

Hi mikebg, do you know why jewellers are interested in meteorites?

Search the WEB for "meteorite jewelry"!
The prices are more than the gold.
Here is the drawing for "almost orthogonal" coil configuration.

[WM6]

Thanks mikebg.

How your "twin loop" RX coil are connected: in parallel or serial, in-phase or in anti-phase?

You say 20kHz is not enough for proper work, did you modify your Lobo to higher frequency?

[mikebg]

Does it really matter? (don't discourage them while they do)

I'm more interested how you locate the approximate meteorite fall site. By asking the locals? I can understand the metal detecting part, but I don't understand how you increase your odds of finding a meteorite in the first place

Davor, do not expect Jim Peterson to reply soon . He is very busy with searching and will hardly find time to participate in the forum because already received one 2box machine model TF-900.

After several days, forum participants can observe meteor shower. Here is the information:

PERSEIDS
August 10/11, 11/12, and 12/13, 2012
Meteors are typically best after midnight, but in 2012, with the moon rising into the predawn sky, you might want to watch in late evening as well. You can get moonrise times via this custom sunset calendar. As seen from around the world, the waning crescent moon will rise later on August 12 than on August 11, and, on the morning of August 13, although you’re slightly past the peak, the moon will rise later still. On any of those mornings, moonlight shouldn’t be so overwhelming as to ruin the show. Plus the moon on those mornings will be near the bright planets Venus and Jupiter in the eastern predawn sky. It’ll be a beautiful early morning scene.

The Perseids are typically fast and bright meteors. They radiate from a point in the constellation Perseus the Hero. You don’t need to know Perseus to watch the shower because the meteors appear in all parts of the sky. The Perseids are considered by many people to be the year’s best shower, and often peak at 50 or more meteors per hour in a dark sky. The Perseids tend to strengthen in number as late night deepens into midnight, and typically produce the most meteors in the wee hours before dawn. These meteors are often bright and frequently leave persistent trains. Starting in late evening on the nights of August 10/11, 11/12 and 12/13. The Perseid meteors will streak across these short summer nights from late night until dawn, with only a little interference from the waning crescent moon. Plus the moon will be near the bright planets Venus and Jupiter in the eastern predawn sky.