The Shop > Electronics & IC Programing
Which lathe (err... Scope) Rigol
PekkaNF:
Hi my name is Pekka and I am an electrical engineer :)
I know that questions like which is best/whatever for first lathe/scope questions are plentifull and hard to answer, but it took me four lathes to learn something on them, and I'm on my third scope and sill know nothing.....
I actullay never done any real electrical design or work, went to work on paper machine insdustry, which had some demand for electrical engineers.
I did a whole lot of study and hobby stuff on electronics lab in the university and spent time with quality instruments, most of them were Tektronix and such.
Hobbyist had no money to buy such stuff. I had 10MHz British made "transitor" scope and later 20MHz Philips tube scope, until I bought Rigol DS1052E 2CH 50 MHz scope.
To my opinion DS1052E is the firts passable scope I owned, but it has some quirks and features that are not exactly show stoppers, but still rather annoying.
1: Lack of 50 ohm input. In priciple no problem: just use 50 ohm. trough termination, but in reallity question is more complex.
True 50 ohm scope inputs seem to be better enginered and have less noise. Often, also sensitivity is better.
Why such a fixation on 50 ohm? I like to build my own probes. 50 Ohm transmission line is the only way to go on hobby planet. It is true, that it's not often really requred under 100-200MHz...and it is limited to low voltage levels - you don't want check thermal capacity of the internal 50 termination.
2: relating to #1, adjustable probe attenuation would be nice. My current scope has pretty much all standard ones, but it's missing 1:20 and no probe DC voltage calbration. Or least I cant't find it.
3: Ergometrics is not the best for me. I learned analog scopes, Gain was always over CH BNC and time scale on extreme right. Don't swap brake and gas on my car! I'm still reaching wron dials. Also the main menu dial ridiculously small and feel is "cheap". I can use the user interface, but "flow" is not natural...press CH1, press button at the side of the screen...reach menu dial, jog menu, press dial, press dial another time...
Also display is rather small, sometimes I'm squinting numbers and thinkking is that comma or dust...I actually checed my tail once nearly two hours, before I figured I had interpreted one value 10x wrong and it was not probe attenuation.
4: Amplifier sensitivity...could be better. I keep on bumpping on low limit all the time. 8 bit DAC and noise does not improve readability.
5: bit more BW would be nice. All low price scopes seem to have max 1 Gs/s, so 100/200MHz nominal max. sine BW is in cards.
Here used scopes are not that common and good used ones (even alanog ones) have unrealistc prices.
My plan "B" is bring older TEK from USA following year, when I'll visit my friends.
But now I have grown into digital scopes and they have benefits.
I have been eyeballing two new options:
A) Rigol DS1054Z 50 MHz 4CH
https://www.batronix.com/shop/oscilloscopes/Rigol-DS1054Z.html
Price is right, dispaly is bigger and it has two channels more (alhough each channel will lower sampling speed and memory).
Ergometrics appears better on youtube videos and it has finer range on probe attennuation settings. But on paper, it is not much of an upgrade.
B) Rigol DS2102E 100MHz 2CH
https://www.batronix.com/shop/oscilloscopes/Rigol-DS2102E.html
Price is larger, but it has 50 ohm input and least on paper better input sensitivity....but it does not look like I would be getting whole lot more scope....if I read specks carefully.
I have this: DS1052E
Analog digital converter (A/D) 8 bits, make sampling on both channels synchronously.
Sensitivity range (V/div) 2 mV/Div to 10 V/Div.
Displacement range ±10 Div. (2 mV - 10 V)
Time base 5 ns/Div. to 50 s/Div. (Steps 1 - 2 - 5)
A) Rigol DS1054Z 50 MHz 4CH
Analog digital converter (A/D) 8 Bit
Sensitivity range (V/div) 1mV/div bis 10 V/div
Offset range 1mV/div bis 10 V/div
Time base 5 ns/div bis 50 s/div
B Rigol DS2102E 100MHz 2CH
Analog digital converter (A/D) 12 Bit at ≥ 5 µs/div, 8 Bit at ≤ 2 µs/div
Sensitivity range (V/div) 500 µV/div to 5 V/div
Offset range 500 µV/div to 10 V/div
same DS indicates this cope as 8 bit, where does those extra bits come from?
However Data Sheet/Vertical Scale
When the input impedance is 50 Ω: 500 μV/div to 1 V/div
When the input impedance is 1 MΩ: 500 μV/div to 10 V/div
Note[3]: 500 μV/div is a magnification of 1 mV/div. When calculating the DC Gain Accuracy, the full scale should be considered as 8 mV (calculated based on 1 mV/div).
So, I'm not getting as much more sensitivy that I might understand from casual reading..
My question is that how much more usefull is 4ch vs. higher BW :lol:
200MHz 4CH and 50 ohm option on termination will drive price up.
I did consider entry level "Brand" scopes, but looks like inthe end I'm getting Rigol with less options and higher price, only difference being name on the enclosure.
Pekka
eskoilola:
First You have to think what You will be measuring. Is it separate events or something that is repetitive (cyclic) or both. This determines whether You need a memory scope or just an ordinary real-time scope.
The memory scopes are nice but since those have to store their data somehow those have a ADC which comes with it's implications. One just cannot see beyond their BW. In an analog scope it is possible to see "hairs" and stuff even when the BW was long gone. Further more the display is not a CRT but merely a computer display so one actually cannot bypass the ADC even if one wants to do so.
I have two scopes. One is a dinosaur (Tektronix ... something) and the other is a HP memory scope with 8 channels and what not. It is on the edge of being a logic analyzer. It is very nice device on measuring separate events like seeing what is there really on the MODBUS.
Another thing You should be aware of is the BW. In my case 100MHz for the dinosaur is enough. It has 4 identical channels and all sorts of triggering options between those. Usually I find myself using the first channel. I am pretty sure I have never used all four at the same time. The triggering on a Tektronix dinosaur can lock beyond the 100MHz ... I have succesfully locked on 270MHz but that was a tad fiddly to do.
I think the minimum requirement for sensitivity is 1mV/division. Never needed less than that.
I think the IMPEDANCE of the inputs in all of my devices is 50 ohms. This does NOT mean that there is a 50 ohm resistor somewhere. Indeed, if I would measure the resistance on my straight probe it would probably be somewhere in the vicinity of one megaohm. The noise level in my old dinosaur is low enough to not to be seen when there are no probes connected. When the probe is there some noise can be seen as the probe is picking up all the interference in the air. If that would be a "true" 50 ohm resistive probe then that interference would not be seen.
PK:
I agree, scopes now come in flavors and it really does come down to what sort of work you are doing.
I
* f it's RF then bandwidth and sample rates are king.
If it's anything with fast micro controllers, then mixed signal and deep capture buffers are getting cheaper by the day.
For motor control then you want 4 channels.
If you are working on industrial equipment then a CatIII isolated handheld is a very handy thing.
*
etc.
As a hobbyist, price is always a constraint.
We are going through this process now at work and have decided that our principle consideration is faith.
What we care most about is that, when we put a probe on a signal, that what we see is actually what is there. We need that confidence above all else. (then we need Mixed Signal with protocol decodes, a big screen and deep buffer).
This is where the kiethley's and tektronix's of the world come into their own.
OK, so tek scope might be, say, 25% better than the equivalent salig, or Rigol and cost 400% more.... but it's 25% better.....
I've seen some great measurements taken with cheaper scopes and there is no doubt they are excellent value for money. But my 100MHz tek 2014 samples at 2Gs/s and has been rock solid for a decade.
I guess it's the same as "Chinese import vs old iron" in lathes....
Anyhow. Just my 2c worth.
PekkaNF:
Thank you
Very informational answers.
And I see that even though my OP was way too long....it was far from complete.
I really need two scopes: planning to buy good, used analog scope for the reasons you both gave (and nostagia - nothing beats good dials and logical lay out that feels familiar). But the right, used (TEK) is going to take some time to find.
Therefore I'm looking a new scope and that has to be digital. I don't feel that I have need for metrosexual scopes (I believe those are called mixed signal scopes, but can't be sure, they do look scopes).
PK, you are right on all those points....
Mains isolation / CATIII that is more of an exception that rule for my current needs. I actually managed to limp along one case by using active current probe (isolated) and I think that HV differentila probe might go long way cost efective. Might be bit marginal for most of the SMPSU's but I don't work with them, more often 50-400Hz mains.
Closest to my motor controls needs are feedback sensors and such....some cases three channels would be nice.
So, I want to buy half decent general use entry level digial scope (new) that has aceptable basic functionality.
I'm trying to get my head around this question:
A) 4 CH, but less BW
B) 2 CH and 50 ohm input, but 2x BW (+300€)
Normally I would go for bigger BW, but sampling rate looks the same on 300 - 1000€ price range, real difference being amount of channels, screen size and bundled serial decoders.
Esko, does you TEK has then TIA input?
https://www.tek.com/sites/default/files/2018-03/FAQ_Passive-probe_Image4.jpg
Some stuff I don't understand well:
https://de.tek.com/support/faqs/why-isnt-tpp1000-%28tektronix-passive-probe-1ghz%29-compatible-my-scope
eskoilola:
--- Quote from: PekkaNF on April 22, 2018, 07:26:19 AM ---Esko, does you TEK has then TIA input?
--- End quote ---
To be honest, I am not sure. My previous scope had nuvistrons and this is the next generation right after that period. As I said, a dino ...
My assumption is that there are j-fets buffering the input and thus the static resistance is really big.
And please, do not ask the type, cannot remember and cannot simply walk to my shop since it is over 1000km away "am Momentan".
I know for sure that the inputs can be put into 300V at the most sensitive setting without any damage. I have accidentally measured the anode voltage of some old tube radios with it. It is so easy to forget that the IF coils are directly connected to the anode circuit ...
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