Electronics > Beginners
Is the Rigol DS1054Z still the best buy for a cheap entry level oscilloscope?
JohnnyMalaria:
--- Quote from: Distelzombie on May 18, 2018, 01:59:01 pm ---What's the purpose of old, failing hardware that isn't calibrated anymore? Training? Like, those toys you played with when you were 1-4? You can't trust what it tells you, so the only thing you can do with it is play.
--- End quote ---
Because old hardware such as analog CRT oscilloscopes can still blow modern DSOs out of the water in some regards, particular the budget DSOs.
I have a DS1104Z (100MHz version of DS1054Z) that I bought last year and a '74 Tektronix 475 CRT scope. For me, XY mode is essential so I can monitor my experiments properly. I don't care if it is "precise". As long as I'm within a couple of percent, that's more than sufficient. I was excited that the Rigol had XY mode - until I came to use it. Here are some short side-by-side video clips comparing the two.
I have yet to come across anything that beats the old CRT scope for this. I can tell at a glance if my equipment (or the thing it is testing) is behaving correctly. It's the best tool for that job. To dismiss something because it is old and analog is short-sighted. I'm all three.
sibeen:
No, no, no, that can't be right, JM.
Nice video :)
I'd just find it strange that someone who doesn't own a cro (yep, I'm old) can be so dogmatic about the use and care of the beasts.
rstofer:
I bought a Tek 485 from eBay about 12 years ago for around $200 and it still works fine. It was well used when I got it and it served up until I bought my DS1054Z a while back. It still has more bandwidth and it works well for things like X-Y mode. No repairs but it probably isn't anywhere near in calibration. I don't really care much about calibration, scopes are 'about' kinds of instruments. It doesn't seem to get the wrong answer either so it's close enough.
I don't see the day when a DSO will replace entirely the capabilities of an analog scope - particularly in affordable bandwidth. It's the same the other way too, I enjoy the measurement features of a DSO.
Both scopes will be staying right where they are.
Old Printer:
--- Quote from: rstofer on May 24, 2018, 02:04:06 pm ---I bought a Tek 485 from eBay about 12 years ago for around $200 and it still works fine. It was well used when I got it and it served up until I bought my DS1054Z a while back. It still has more bandwidth and it works well for things like X-Y mode. No repairs but it probably isn't anywhere near in calibration. I don't really care much about calibration, scopes are 'about' kinds of instruments. It doesn't seem to get the wrong answer either so it's close enough.
I don't see the day when a DSO will replace entirely the capabilities of an analog scope - particularly in affordable bandwidth. It's the same the other way too, I enjoy the measurement features of a DSO.
Both scopes will be staying right where they are.
--- End quote ---
Ditto on this. I have a 475 that I bought on ebay about 12 years ago as well. I worked fine then and does so now. I have a 2225 that I paid $100 last year and it works great as well. I look forward to getting my first DSO soon, but these two "dinosaurs" are not going anywhere, and with full factory service manuals for both I will likely be able to keep them running for as long as I am. :) For the price these things can be had for now I think it's silly not to have one.
IDEngineer:
I'll carefully tread into this whole "are analog scopes worth having anymore?" discussion.
This thread's originator said "I've never used an oscilloscope before." With that in mind, I recommend he START with an analog scope. You can often find them on Craigslist, eBay has lots of them, and (since his username looks like a ham call sign) hamfests commonly see a few and/or local hams may have one they're willing to part with. Plus he has an offer for a FREE one, doesn't get much better than that.
Don't view this as "No, I don't want it. It will set the day I get a proper scope back even further." Buy the digital scope on the same schedule you had planned. But LEARN about scopes by starting with the analog unit. Why? Because you will be "closer" to the signal with the analog scope. Digital scopes, with their sample memory and triggering that moves around within that memory, add layers of abstraction that you don't suffer with an analog. Analog scopes also have things I don't often see on digitals, like linearly variable amplitude and sweep. You won't spend lots of time on them but they are immensely valuable in acquiring a gut-level, intrinsic feel for how a scope actually works. The analog scope doesn't need to be in calibration. It doesn't even need fancy features. You need a horizontal sweep, a vertical amplifier, and a triggering circuit. Just those three things will teach you more than you realize, and all of that deep understanding will transfer directly to your new digital scope and make you far more proficient with it. Remember, you said "I've never used an oscilloscope before." The more, and easier, you learn about what a scope actually does, the better you will be at using ALL scopes.
If it were me, I'd fire up the analog scope, switch its trigger to Auto, and put some repeating signal on the input. Even just the scope's own integrated square wave (used for calibrating probes) will work. You'll see a scrolling waveform on the screen. Play with the vertical sensitivity and get a feel for what happens on the screen. Play with the variable sensitivity knob too.
Then play with the horizontal timebase. See how the waveform's visibility changes as you speed and slow the sweep rate. There will be a point where, perhaps with the help of the variable sweep knob, you can almost kinda sorta get the waveform "stable" and see its shape.
This is already more visibility than you had with no scope at all, and even if you don't realize it you're training yourself to treat the scope not as this discrete "tool" but as an extension of yourself. Like wearing glasses, eventually you don't think about the tool and the tool just becomes part of YOU. You're already using two of the main sections of the scope.
Now, it sure would be nice if you could stabilize that waveform on the screen, right? So it would stop moving around and you could really examine it. That's what the third main section, the triggering system, does. Switch the triggering system to Normal. If the screen went blank, don't panic... the triggering system will only let the trace move across the screen if the input voltage crosses the trigger level threshold. Now try varying the trigger level until the trace (re)appears. Note that it's stable now! The trigger system only lets the horizontal sweep occur when the input voltage crosses the trigger voltage level. You change that voltage with the trigger level knob.
If you have access to a sine wave (this example doesn't work well with a square wave - can you figure out why?), use that and vary the trigger level. You'll see the sine wave move left and right as you change the trigger level, because as you change the trigger level it matches the sine wave at different places. Also try inverting the trigger slope. See what happens to the waveform on the screen.
Now, find another signal source. Maybe a serial data stream, like RS-232 or CAN or USB or something. By using Normal trigger mode you will probably be able to get a psuedo-stable display, and by varying the horizontal timebase you should be able to fill the screen width with roughly one byte/packet. The waveform may be changing, but that's just the varying bits in the data stream.
Now, without changing anything else, switch to Auto trigger mode. Lots of horizontal scrolling now, right? Can you explain why? Hint: Auto mode just mindlessly starts the next horizontal sweep when the previous one finishes. How does Normal mode differ from that?
Play around - and I really do mean PLAY - with the analog scope like this, looking at every signal you can find. An hour or two of this and you'll develop an innate sense of how to tune the scope to the signal. You won't look for the "right" button or knob, your fingers will just go there. You'll stop thinking of the scope as separate from yourself, and start thinking more about the signal you're investigating. And all of this will transfer directly to your new digital scope. You'll be more proficient with it, faster, than without the analog scope experience.
Could you do this starting with a digital scope? Sure. But it is my humble opinion that it will take you longer to become equally proficient, and you miss out on the "scope zen" that you'll quickly develop with the analog scope.
I could go on and on, but hopefully you get the idea. Hope this helps!
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