THREE COINS IN THE P.I. FOUNTAIN

[mickstv]

No I've only got an old analog CRO, ATM.

I've just monitored the same targets but now looking at the DC out of the main diff integrator with the Ground Balance circuit disconnected results below.

Sample is 10us in width and 10us from TX end.


No spacer...

1x 50c = 180mv
2x 50c = 176mv
3x 50c = 185mv


A4 spacer...

1x 50c = 180mv
2x 50c = 178mv
3x 50c = 192mv


5mm spacer...

1x 50c = 180mv
2x 50c = 252mv
3x 50c = 315mv

[Mechanic]

HI Mick,?

For those results, if there was no target was the voltage measured as 0v?
And did you have a late 10us sample also, well out from where the target signal has decayed away?

Cheers Mick

[mickstv]

Hi Mick,

Yes 0v for no target (TX coil common rail). I didn't have a second sample running, I also disconneced the other side of the diff-int and connected the pin 3 input to the TX coil common rail.


Cheers
Mick

[Mechanic]

HI Mick, try it with a second very late sample and see if the results are different, though I spose they will be the same.

Cheers Mick

[mickstv]

Hi Mick,

I reconnected the diff-int and modded the Micro code to put in a late single sample, but the end result was the same as previously posted.

Later I'll reload the ground balance code and see what happens to the target response.

[mickstv]

I loaded the GB code in and did a rough GB. With one 50c the output still goes positive, but when I add a second coin the output of the diff int goes negative past 0 volt common, so the target is being picked up more in the GB channel.

[Ferric Toes]

I loaded the GB code in and did a rough GB. With one 50c the output still goes positive, but when I add a second coin the output of the diff int goes negative past 0 volt common, so the target is being picked up more in the GB channel.

Somewhere I have some recent Oz coins. When I find them, and if I have a 50c, I will do a plot.

Eric.

[mickstv]

Somewhere I have some recent Oz coins. When I find them, and if I have a 50c, I will do a plot.

Eric.

Hi Eric, if you can't find them I can send a few in the mail, just send me an email.

Cheers
Mick


Back onto the 50c and GB, if I hold the second 50c a certain distance from the first one, both vanish. Electronic hole ?

[Aziz]

Discrimination Effort?

Is this the discrimination effort?
I can tell you, that it is purely waste of time.
Mr. Candy can't do it either even he is trying to patent something to discriminate different time constant targets.

We should focus to the Ground balance thread!

Aziz

[Prospector_Al]

Hi Eric, if you can't find them I can send a few in the mail, just send me an email.

Cheers
Mick


Back onto the 50c and GB, if I hold the second 50c a certain distance from the first one, both vanish. Electronic hole ?

Hi Mick,

The phenomenon of "Electronic Holes" has been known for some time, but you have demonstrated it in a very elegant way. This could be duplicated with coins of other sizes and even with a coin and a nugget. Perhaps even with two nuggets?

Are you by any chance related to the Prince of Serendip? I guess you didn't set out to find a hole, so this was a lucky accident...

Best Regards,

Allan

[Ferric Toes]

Is this the discrimination effort?
I can tell you, that it is purely waste of time.
Mr. Candy can't do it either even he is trying to patent something to discriminate different time constant targets.

We should focus to the Ground balance thread!

Aziz

On the contrary it is time well spent. I have an important project at the moment where the information I have researched on multiples of coins is essential knowledge. I would say that we are all free to choose what is important at any one time, and for me at the moment Ground Balance is on the back burner. That is not to say that I will not come back to it shortly, but for the moment you are on your own.

Eric.

[Ferric Toes]

Hi Eric, if you can't find them I can send a few in the mail, just send me an email.

Cheers
Mick


Back onto the 50c and GB, if I hold the second 50c a certain distance from the first one, both vanish. Electronic hole ?

Hi Mick,

I found one 50c coin and it measures 5.5% of the conductivity of the copper standard; exactly the same as our old half crown, and about the same size, so the two coins are identical electrically. I found that at 100uS delay, the initial reading stars to increase from 25 when the second coin is about an inch above the first, until the reading is 161 when sitting on top of the first. This all indicates a substantial increase in TC. With subtractive GB in operation, you would be fine tuning the TC to the point where the GB ignored the two coins as they have dropped into the notch. The same thing happened with all of the cupro-nickel coins I have. Coins with higher conductivity behave a bit differently. The TC goes up initially but reaches a point when the second coin is close to the first when the TC goes down again. US quarters gave really strange results. Maybe there are different layers to the core and the plating on the surface has a reaction too. Look into that further when I have more time.

Eric.

[Ferric Toes]

Hi Mick and Allan,

I forgot to mention that when coins are side by side in the same plane you do not get the TC enhancement as the mutual coupling is greatly reduced. The same would be true for nuggets.

Eric.

[Overtheedge]

Consider the two coins side by side as coils closely coupled being equally illuminated by the powered coil. They would be out of phase with each other to a large degree. Ergo a drop in the re-emitted field strength and if looked at in the time domain, quite variable in amplitude.

One might ask, "What are the odds of two or more coins resting side by side?" Uh, the change fell out of the pocket while the person was relaxing/reclining.

But I'm kind of new to this and I hadn't considered the side by side coin effect. Thanks.
eric

[Ferric Toes]

Consider the two coins side by side as coils closely coupled being equally illuminated by the powered coil. They would be out of phase with each other to a large degree. Ergo a drop in the re-emitted field strength and if looked at in the time domain, quite variable in amplitude.

One might ask, "What are the odds of two or more coins resting side by side?" Uh, the change fell out of the pocket while the person was relaxing/reclining.

But I'm kind of new to this and I hadn't considered the side by side coin effect. Thanks.
eric

Some years ago a PI detector user here dug a signal which at first sight looked like an iron concretion. He wacked it with his spade and out shot a coin. So he took the brown lump home and cleaned it up and what it turned out to be was a Victorian leather purse, inside which were some silver coins together with a gold sovereign. A good example of coins being in very close proximity.

Eric