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True analog scopes
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Fungus:

--- Quote from: MrAl on December 26, 2022, 09:08:59 pm ---If the scope could measure rise and fall times that would help.  Mine does not have that function though but i see some of the upper echelon scopes have that feature.

--- End quote ---

It's an entry-level feature these days. Even the venerable Rigol DS1054Z does it.

AVGresponding:

--- Quote from: MrAl on December 26, 2022, 09:08:59 pm ---
--- Quote from: tautech on December 26, 2022, 08:02:25 pm ---Something I don't miss at all with analogue scopes....all the mental arithmetic just to use the scope vs a DSO that when set correctly excludes all that BS and instead lets you focus on the DUT measurement instead.

Pinched from another thread as a fine example:

Apparently using a 100x probe.

 :horse:

--- End quote ---

Yes that's a good point the digital scopes can measure things right away.

I remember years ago trying to measure the rise, slope, and fall times of switching waveforms in high power converters so i could estimate the switching losses.  It took about 15 minutes to get right and the calculation had to be done on a calculator or computer.
If the scope could measure rise and fall times that would help.  Mine does not have that function though but i see some of the upper echelon scopes have that feature.

--- End quote ---

That's a Tek TDS display. My TDS420A can measure rise times, and fall times. In fact it has 7 pages of things it can measure (4 items to a page in fairness).

How much did I pay for this upper echelon 'scope? £100. Shipped.
tggzzz:

--- Quote from: baldurn on December 26, 2022, 09:35:17 pm ---
--- Quote from: tggzzz on December 26, 2022, 09:28:51 pm ---
I would have thought that if traceability and reproducibility was required, then there would be reluctance to rely on a complex black box calculation.

Spreadsheets (and computer programs) often contain errors, but they can be challenged, examined and corrected in a way that firmware cannot.

--- End quote ---

If you enable the statistics function to gather data for more than just one random screenshot, there simply is no alternative?

If it is just for one random screenshot, just include that screenshot. Anyone can reproduce the calculation, albeit probably not as precise.

--- End quote ---

MrAl was doing a complex test-specific calculation of switching losses, not a simple standard stats function.  If the measurement is important, it needs to be visible and reproduceable, which is questionable if done inside one specific instrument. (just like a spreadsheet calculation without the formulae being visible)

Here's the relevant context you snipped...

--- Quote from: MrAl on December 26, 2022, 09:08:59 pm ---I remember years ago trying to measure the rise, slope, and fall times of switching waveforms in high power converters so i could estimate the switching losses.  It took about 15 minutes to get right and the calculation had to be done on a calculator or computer.
If the scope could measure rise and fall times that would help.  Mine does not have that function though but i see some of the upper echelon scopes have that feature.

--- End quote ---
tggzzz:

--- Quote from: Fungus on December 26, 2022, 10:20:36 pm ---
--- Quote from: MrAl on December 26, 2022, 09:08:59 pm ---If the scope could measure rise and fall times that would help.  Mine does not have that function though but i see some of the upper echelon scopes have that feature.

--- End quote ---

It's an entry-level feature these days. Even the venerable Rigol DS1054Z does it.

--- End quote ---

If his.calculation was that simple, why did it take 15 mins? If it took 15mins, it would have been so specific and complex that it wouldn't have been a standard scope feature.
baldurn:

--- Quote from: tggzzz on December 26, 2022, 10:38:35 pm ---
MrAl was doing a complex test-specific calculation of switching losses, not a simple standard stats function.  If the measurement is important, it needs to be visible and reproduceable, which is questionable if done inside one specific instrument. (just like a spreadsheet calculation without the formulae being visible)


--- End quote ---

Yes and how do you know how precise that measurement is if you do not do statistics on it? Just to be sure, since this thread IS about analog vs DSO, how would you do it with an analog scope (a true analog scope, not those half digital things that can do digital measurements)? I am actually curious and does not know the answer. Would it not be in fact be hard and time consuming to get the same level of precision, that we get by default just by pressing the stat button?
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