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EEVblog 1632 - WHY sell 2CH Oscilloscopes? + Test Engineering

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EEVblog:
Why do companies still sell 2CH oscilloscopes? Plus a massive tangent into test and production engineering. Also showing one of my old test engineering projects.



LCR meter and Transmission Line Tester design:
Relay Matrix IR Measurement:
PC104 Embedded DOS PC:
Linus Tech Tips Test Rack:
Test rack Part 2:

pdenisowski:

In my experience there are many scope users who are unaware of how scopes are used in manufacturing / production, and this video is a great explanation - thanks!

EEVblog:

--- Quote from: pdenisowski on July 29, 2024, 07:46:59 am ---In my experience there are many scope users who are unaware of how scopes are used in manufacturing / production, and this video is a great explanation - thanks!
--- End quote ---

I got hammered in the comments about cheap 2CH scopes!   :-//

BrianHG:

--- Quote from: EEVblog on July 29, 2024, 09:45:54 am ---
--- Quote from: pdenisowski on July 29, 2024, 07:46:59 am ---In my experience there are many scope users who are unaware of how scopes are used in manufacturing / production, and this video is a great explanation - thanks!
--- End quote ---

I got hammered in the comments about cheap 2CH scopes!   :-//

--- End quote ---
Putting aside that there are valid markets for 2 channel scopes, boy how spoiled we have all become demanding 4 channels.  When I grew up, any 2 channel scope was a luxury.

Gyro:
Just because cheap 4 channel scopes are on the market, there's no need to question the use of 2 channel scopes, we're not all doing the same stuff. Why stop at 4? Why not insist on an 8 channel scope.

- Fundamentally a scope is there to examine the timing relationships and integrity of signals. The minimum you need to do that is... 2 (ok you can look at the integrity with 1). It's an analogue domain tool.

- The number of channels needed to do an X-Y phase relationship is... 2.

- Everyone knows that any decent 2 channel scope has an external trigger input anyway, so that gives you the timing relationship of 3 signals with intelligent use, and no loss of sample rate.

- Screen resolution on DSOs (or minimum analogue spot size, lest we open up that argument!) is very low - typically 480 pixels vertical on an 8 bit and a whopping 600 pixels on a 12 bit! In the grand scheme of things, that's pathetic! :palm:  Trying to squeeze 4 traces on a a screen and see any reasonable vertical resolution is a joke.

- Just because manufacturers can cheaply stuff in another couple of front-ends is a nice sales feature doesn't make them good. On a typical cheap scope, enable all four channels and the sample rate and buffer size drop through the floor. For example, going back a bit, what was the point of hacking a DS1054Z to 100MHz when the sample rate was only 250Msps with 4 channels enabled.

- Protocol decoding on scopes is a cheap (free) S/W gimmick to sell more scopes. Half the time they get it wrong and the display format is typically very basic. If you are working on digital stuff, after verifying signal integrity in the analogue domain, move to a tool suited to the digital domain... a logic analyzer. Singing the praises of the minimal  decode facilities of a 4 channel scope is just discouraging the manufacturers from putting decent and affordable digital domain tools on the market.

- I wonder how long it will be before you put out a video saying 'geez why would you buy a 4 channel 12 bit scope when you can get a cheap 6 or 8 channel 16 bit'. I bet the vertical resolution will be up to, oh, 1024 pixels by then.


Edit: Reading that back after a couple of hours, I sound a bit irate, sorry about that.

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