| Electronics > Beginners |
| Extremely basic oscilliscope questions for a beginner |
| (1/2) > >> |
| sofakng:
I'm trying to learn electronics and I purchased a Rigol 1054Z during an eBay sale at the beginning of the summer but I haven't learned too much yet. I'd like to troubleshoot an HDMI connection and the HPD signal (0-5v on/off) and the +5V power quality. My theory is that the HPD line is dropping below 5v causing drop-outs on my TV and I'd like to if this happening and if so, how often it's happening. I'd also like to see the +5V signal (different wire) and how closely it's sticking to 5.0v. Here are my questions: 1) Does a digital oscilloscope draw from left to right and then once it reaches the right, it continues drawing from the left again? I think of a signal as continuous; starting and then going on forever so this type of display is confusing me... 2) Do I want to use ROLL MODE for my above measurements? I'm not looking at a wave form in my situation, but instead want to see how often an event is occurring and the quality of a signal. Also, does roll mode function more like I describe above (ie. a signal going on forever constantly drawing on the right side of the screen... this seems more useful than a left-to-right, left-to-right, type of display?) Sorry for my extremely basic questions! I'm trying to read, watch, and learn as much as possible but some things I just can't get through my thick head. |
| ArthurDent:
Generally the ‘roll’ mode is for very slow signals. If you’ve seen medical monitors where they are displaying heart rate, the current image position appears centered as the trace is scrolling across the screen from right to left. The older scopes that had CRTs would sweep from left to right across the screen then there was a ‘blanking pulse’ that would allow the trace to almost instantly zip back to the left where it would start drawing again. The new scopes do something that looks the same but they are displaying what is written in memory on the LCD screen. |
| vk6zgo:
Analog 'scopes have a function which was commonly referred to as "free running", where the sweep is running continuously, not needing triggering from any input signal. This was convenient for looking at DC voltages, as when DC coupled, the position of the line on the screen would be deflected vertically by an amount depending on the voltage & the volts/div setting of the Oscilloscope. With early DSOs, there was not a real equivalent function, meaning that people had to use "work arounds". The "roll" mode was one of those used, but it was not very useful, seeing & displaying the change in voltage as a slow pulse. Modern DSOs do have a real equivalent to "free run" & can be used in the same way as their analog predecessors. |
| StillTrying:
--- Quote from: vk6zgo on September 07, 2018, 12:59:43 pm ---Analog 'scopes have a function which was commonly referred to as "free running", where the sweep is running continuously, not needing triggering from any input signal. --- End quote --- Just AUTO trigger on a DSO ? When probing mostly DC voltages such as around a logic IC, AUTO trigger keeps starting and stopping, ....so I sometimes switch the trigger to AC line, which gives a permanent trace, which you see flicking up to 5V - or not, without taking your eyes off the IC pins/probe. |
| vk6zgo:
--- Quote from: StillTrying on September 07, 2018, 02:08:03 pm --- --- Quote from: vk6zgo on September 07, 2018, 12:59:43 pm ---Analog 'scopes have a function which was commonly referred to as "free running", where the sweep is running continuously, not needing triggering from any input signal. --- End quote --- Just AUTO trigger on a DSO ? When probing mostly DC voltages such as around a logic IC, AUTO trigger keeps starting and stopping, ....so I sometimes switch the trigger to AC line, which gives a permanent trace, which you see flicking up to 5V - or not, without taking your eyes off the IC pins/probe. --- End quote --- Would it be better with a faster time /div setting in AUTO? (that's also what they call it on analog 'scopes) I didn't bring up the term AUTO because of possible confusion with the AUTOSET button on DSOs. I think there was a discussion on this forum about AUTO trigger. From memory, the repetition rate of drawing the line on a DSO in that mode doesn't directly follow the time/div setting, (It is quite a bit slower, whereas with an analog instrument it is a little bit faster), but it does change with the setting of that control. I don't have a modern (or indeed, any) DSO, so any information on their function had been gleaned from the Internet, (mainly from this forum. |
| Navigation |
| Message Index |
| Next page |