Standard targets

[ivconic]

Obviously good method.
Come to think; what if single pulse is shot, say 100uS width and than immediately cut off, providing the oscilloscope with at least 5uS sensitivity and hold function (my middle class scope have 1uS sensitivity and 0.2-0.5uS x10 uncal).
And then just hold (freeze) complete decay slope on the RX side (my scope is not having this... or I have no clue how to do it! lol)
There must be way to "trick" this somehow and get most precise calc.
Some pc based scopes have nice hold function but sensitivity is close to useless.
You mentioned "overload" and that's a bit confusing for me, aren't there clamp diodes at the input? And the RX opamp can have offset adjusting feature.

[Carl-NC]

If you have an analog scope it cannot hold the waveform. For this method, you also have to be able to save the oscope data points. This requires a digital scope. An analog scope could be used with a log amp, as Green described in a prior thread.
The purpose of the diodes is to prevent the preamp from burning up, it will still overload. An offset won't help, the signal is just too big.

[Altra]

Carl, I get what you are saying now. You can calculate the tau any where along the linear slope.

[ivconic]

If you have an analog scope it cannot hold the waveform. For this method, you also have to be able to save the oscope data points. This requires a digital scope. An analog scope could be used with a log amp, as Green described in a prior thread.
The purpose of the diodes is to prevent the preamp from burning up, it will still overload. An offset won't help, the signal is just too big.

As I afraid... and the digital scopes with good sensitivity are usually not affordable for modest budget hobbyists... aka me!
About the clamp diodes I understand... ok I see, thanks!
So the best tradeoff would be super fast opamp at the RX, right... again "catch 22" for the modest budget hobbyists!

[ivconic]

Moodz, Tony... send me pile of those opamps you so despise!

[Skippy]

"Skippy: after reading through the various threads, you seem to be the dominant contributor on this subject. Maybe you should compile and write a article on targets"
Those threads are unfinished business, I don't have much time to add to them, never mind try and compile it all together, unfortunately.
"It's hard to Search out the real information spread all over the place."
Unfortunately, that's forum's for you. Though those threads were on different subjects - big targets, nuggets, building a test jig, they end up containing overlapping information.
I don't know. That Fake Dollars thread is now part of the Archived "Old Forum" , so it's preserved in that respect. I suspect Tom would hate to lose the archive, even if the current forum languishes.
And regarding my time-constant figures: they are all taken on a 13kHz VLF, never a PI. I don't own a PI, and have little interest in them, to be honest. I also have no interest in nugget-hunting, as we don't have them in the U.K, so short-TC targets are not an obsession of mine.

[EL NINO]

it is clear that the standardization of test targets is a good thing if the results are to be shared with other testers.. I also adopted the goals from the geotech1 forum for my testing..

[moodz]

Moodz, Tony... send me pile of those opamps you so despise!

1 ton of 741's on way.

BOE741 Boeing Flight Tracking and History - FlightAware

[ivconic]

I have no experience with the 741, the last time I flew was a 737, a short "fat one" whose screws were unscrewed during takeoff...

[ivconic]

It's just a story, worthy of a BBC comedy series, "Black Adder" comes to mind!
I get into a half-empty plane, fly to Malta, Valletta, but before that we land in Tripoli, Libya...
the local company has no financial justification to fly directly, but collects as many passengers as possible along the way so that it all makes some kind of financial sense.
The plane looks worn, although it is clean and tidy, but it looks quite worn. The crew... all medieval "milf" beauties, with huge thighs and cream-hidden wrinkles...
I, as a locally known admirer of the character and work of the beautiful part of the female world... immediately at the start I realize that there is no work for me there.
So I immediately set about destroying their supply of liquor...
We are waiting... but finally the moment comes to go.
The convention is that before take-off the pilot, with the two most beautiful flight attendants, comes to the passengers and greets the passengers and wishes them a pleasant flight.
A pilot enters, about my age, with long greasy hair full of dandruff, layers of dandruff on his shoulders as well, his uniform is "white" from dandruff!
A face intertwined with red capillaries, a typical face of an alcoholic who probably spent several sleepless nights with heavy doses of alcohol!
Lazy muttered a welcome and then went to the cabin. Off we go. We are rolling. We will take off to a certain height in a slight ascent.
And then suddenly the plane straightens up almost vertically, with a huge engine noise and terrible vibrations!
The idea is to reach a height of 10,000 meters and then fly completely horizontally. It all takes less than a minute, maybe two.. no more.
But for me it took forever, my whole life flashed before my eyes!
It "took so long" that I even had time to calmly analyze the screws on the luggage area above me... how they shake and slowly loosen!
Only later did I find out that this is a completely normal situation when it comes to the 737, which is short and fat, and that's why the take-off method is like that...
Did I survive it? I don't know... honestly. Either this is really me writing this or it's some internet virus simulating me!