All flat displays need a frame-buffer, which is inherently storage. You can write into a frame buffer emulating an electron beam upto a certain rate, digitally, so an ADC is required. At higher update rates the drawing cannot keep up and you have to store the samples and draw the screen off-line. This is presumably how the old kits for turning a TV into a 'scope work.
The display driver chip(s) will scan the frame buffer row-by-row to update the display, a sequential pattern.
In a CRT the electron beam scans in any direction in real time which is rather different.
An LCD display is not solid-state, the clue is in the name 🙂
The display driver chip(s) will scan the frame buffer row-by-row to update the display, a sequential pattern.
In a CRT the electron beam scans in any direction in real time which is rather different.
An LCD display is not solid-state, the clue is in the name 🙂
I agree almost fully with you.
Analog CRT-scopes were made mainly for analysis of analog circuits, such as amplifiers, linear power regulators and radios. The CRT-scopes did and still do well for such use.
The moment the focus turned toward digital circuits, the CRT-scopes became of little use because you need less precision but much more intelligent analysis and flexibility for digital circuits.
I have an old but well functioning Hameg (German) CRT-scope and a cheap USB-scope (8-bit sampling) from out east. As my interest is mainly analog circuits, that combination serves me well for the time being. The day I can buy a 12-bit sampled, 50MHz bandwidth scope for a hobbyist price, my Hameg will be of little use. 16-bit, 100MHz is my future dream.
Hmm, strange that an analog scope can be so slow... sorry cant come to think about anything really...
Did you say what brand and model?
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Did you say what brand and model?
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Cheap chinese scopes (Rigol, Hantek, etc.) are linux computers running on ARM with dedicated FPGAs for the sampling. Yes, there is an inevitable latency in reading the samples pre-stored by ADC in some memory buffer and displaying them in a nice form on the computer screen (being the internal LCD). Very likely an open source scope firmware would be able to offer a low-latency display mode with latency unnoticeable by bare eye. But I do not know of any open source linux installation supporting the undocumented hardware APIs.
I know nothing about the "good" scope brands, but likely a similar design.
I know nothing about the "good" scope brands, but likely a similar design.
Okey 🙂
You have to excuse me of jumping into conclusion... I mean the thread title and all...
"Flat screen analog oscilloscope .. ?" ;-D
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The problem I have with digital scopes is that I find it much more difficult to notice things like a little bit of parasitic oscillation at the top of a sine wave. A good analog oscilloscope shows this very clearly.
If some of these digital scope manufacturers could start focusing on making them more usable rather than cramming as many features as possible into them, that would probably help. Some of these scopes have so many features and options that it makes everyday usage a bit of a chore.
If some of these digital scope manufacturers could start focusing on making them more usable rather than cramming as many features as possible into them, that would probably help. Some of these scopes have so many features and options that it makes everyday usage a bit of a chore.
I am with you there H713 ,realized that early on , no way would I trade in my old Tektronix 2445A scope for an all singing -all dancing digital screened model .
My old scope can show detail that cant be seen on those new scopes and as a bonus I am not forced to pay for "app updates " to it.
What you mention about --"a little bit of parasitic oscillation " is exactly my point - missed in those small fully digital scopes give me a CRT every time.
I can expand sections and details to easily see this , in other words ----definition-definition -definition.
My old scope can show detail that cant be seen on those new scopes and as a bonus I am not forced to pay for "app updates " to it.
What you mention about --"a little bit of parasitic oscillation " is exactly my point - missed in those small fully digital scopes give me a CRT every time.
I can expand sections and details to easily see this , in other words ----definition-definition -definition.
What is the resolution of a good analog o'scope CRT display? I know it's fine, but how fine? Are there numbers published or tested?
I work in broadcast video and we went from analog waveform and vector scopes to digital some time ago. While the fine resolution may not be there now by looking at the waveform on an LCD monitor, there are other advantages. The large size helps a lot, as does the color display which allow you to easily see 3 things at once.
I work in broadcast video and we went from analog waveform and vector scopes to digital some time ago. While the fine resolution may not be there now by looking at the waveform on an LCD monitor, there are other advantages. The large size helps a lot, as does the color display which allow you to easily see 3 things at once.
Its fine enough that even my old eyes can spot the tiniest HF oscillation and the square wave tests using a high speed signal shows up the tiniest discrepancy Pano .
I have the large hard-backed industrial manual from Tektronix I will have a look through it to see if it tells me what you want to know .
I have already said the new scopes are -quote-"all singing-all dancing " ,
Just looking at my old PC screen which is 1080 on expansion the picture detail is blurred .
On my new PC with much higher resolution ( and price tag ) its much better but still doesn't equal a high quality Tektronix CRT screen.
As well as a 10X magnification I can target a small section of the sweep and expand that what public available modern small scope can show that minute amount of detail?
I have the large hard-backed industrial manual from Tektronix I will have a look through it to see if it tells me what you want to know .
I have already said the new scopes are -quote-"all singing-all dancing " ,
Just looking at my old PC screen which is 1080 on expansion the picture detail is blurred .
On my new PC with much higher resolution ( and price tag ) its much better but still doesn't equal a high quality Tektronix CRT screen.
As well as a 10X magnification I can target a small section of the sweep and expand that what public available modern small scope can show that minute amount of detail?
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I don't the answer to that. I do know the fine detail that can be seen on the monochrome CRT. Just curious as to how fine it might be and what sort of resolution an LCD display would need to match it.
Please do post the details if you find them in the manual. I think it would be easy to test, tho a little time consuming. Of course it's not all in the display, the ADC will be a limiting factor.
Please do post the details if you find them in the manual. I think it would be easy to test, tho a little time consuming. Of course it's not all in the display, the ADC will be a limiting factor.
Flat Panel Real Time Scope
I would like to have something like the drawing
BUT with way more pixels.
Say 255 x 255
Perhaps addressable with 8 bit counter and flash ADC
Using either a converter to HDMI ? ... Composite ?
Or a graphics display .......
BUT
I'm stymied from even getting started : (
I would like to have something like the drawing
BUT with way more pixels.
Say 255 x 255
Perhaps addressable with 8 bit counter and flash ADC
Using either a converter to HDMI ? ... Composite ?
Or a graphics display .......
BUT
I'm stymied from even getting started : (
