NEW TECH PHOTOS

[nick_f]

Well done, Noemio. I just sent all the modified images to Tinkerer, but yours looks better. I would suggest to write "Penny" with white colour, because it is easier to read. How did you change the color of the layer to red?

Regards,
Nicolae

[Noemio]

GIMP

GIMP, my friend, a LOT of GIMP!
Did you noticed that the frame of the oscilloscope disappeared?
Select the grid, crop, change perspective, increase contrast, threshold, select by color, reduce selection, invert selection, delete, invert selection, fill with new color, etc....etc.......
Do you know what I mean?



Ciao

[nick_f]

GIMP, my friend, a LOT of GIMP!

Do you know what I mean?



Ciao

Hey, Noemio

I know what you mean, I know a little bit about Gimp. I got to almost the same results as you with fewer commands and I actually modified all the images that Tinkerer uploaded and sent them back to him.
Here's one for you. I said your looks better, didn't I?

Regards,
Nicolae

[Tinkerer]

Noemio and nick_f,

Thanks for the help.

Here is # 10, a Dime or US$ 10c. This coin is much smaller, but has a TC that is much longer than the TC of the Nickel. Note how the PIVOT is outside of the sampling window.
The alloy is only slightly different from the alloy of the Nickel.

Tinkerer

[Noemio]

nice job!

Hmmmm, nice job!
Obviously assuming that the shooting angle and distance is always the same.
I preferred to extract the grid and reshape it just to be sure...

[nick_f]

Noemio,
You are right about shooting angles that may be different. I visually checked the images and they look quite similar from this aspect. The question is if you are willing to modify all the images this way. If not, I can do the rest of them in the same manner as I did so far.

Regards,
Nicolae

[Tinkerer]

Here is an EXCEL file with the metal contents of different coins. It shows that a difference of a few percent of the one or other metal can change the response of the coin considerably.

The same happens with gold alloys. An 18 carat gold jewel can be made out of a great variety of alloys. The only thing that the "18 carat" denomination means, is that there is 75% gold in the alloy.

Tinkerer

[Tinkerer]

Here comes #11, the Quarter or US$ 25c coin.

Tinkerer

[Tinkerer]

Target #12 is a steel nail. It is rather large. It is standing on the coil on the same spot as the other targets of this series and the same gain is used.

Note how the response is negative. Compare with the response of the quarter that was positive of somewhat similar amplitude.

With the length of the nail being more than the radius of the RX coil, there would be a significant difference of response, with the nail in the horizontal position.

Tinkerer

[Tinkerer]

Now let's go to the small targets.
Target # 13 is a 1 gram gold bar of 999,9 pure gold.

Its response is weak, but considering the low gain it is still good.
It has a very short TC, so you can observe the PIVOT.

Tinkerer

[nick_f]

Hi Tony,

It looks like you completed the series of photos for your targets. I will process them tonight and attach them here.

Regards,
Nicolae

[Tinkerer]

Hi Tony,

It looks like you completed the series of photos for your targets. I will process them tonight and attach them here.

Regards,
Nicolae

Hi Nicolae,

No, there are 3 more. The aluminum foils.
# 2 in a halve inch square aluminum foil. It is very thin, so I had to stick a tape on it so I could handle it.
It has a TC of about 5uS. Many detectors are not capable to detect it at all.
Here I show its response with only 100 gain and a setting of 200mV / div. on the scope.

Tinkerer

[Tinkerer]

# 3 is a one Inch square aluminum foil of the same thickness. It has a TC of about 10uS. this means that if the eddy currents have an amplitude of 100 mV at the peak and you sample at 20uS after switch OFF, your signal will only be about 15mV at best.

Tinkerer

[Tinkerer]

This is the last one of the series.
# 4. It is a 1 Inch by 2 Inch square alu foil.
It is interesting in that it represents a large surface with very little mass, so it really shows the skin effect.

It is also a good target to show the PIVOT.

Tinkerer

[Tinkerer]

Tinkerer, I get a lot out of your scope shots but I would like to make a suggestion. If you have more than one or two fotos in a batch, is it possible to number (or label) your photos so that we can more easily reference back to your index numbers or description? * (I guess it's too late now).

I may download these and imprint some descriptive text on them for my future reference.

Anyway, thanks for the shots. This kind of stuff has been pretty much ignored in the past.


*Oh, and I'd like french fries with that.

edit: Really you should probably ignore my suggestion. I'll trust you not to mix the fotos up, and make my own captions.

Hi porkluvr,
If I can get a team together to make an "Open Source" design, Discriminating IB-PI, I am going to ask Carl to give us a dedicated forum for it.

I would like to invite you to participate in the team.

Tinkerer