What osciliscope to get?

How much would I realistically have to spend to get an osciliscope like this?


  • Total voters
    4

Thread Starter

-live wire-

Joined Dec 22, 2017
911
Hi, I would like to work on more advanced circuits, and to really see what's going on, an oscilloscope could really help. Some projects are a high power HV arc lighter and other stuff with many ICs and such. Where can I get a reliable and good oscilloscope for under $300-400? I would also like multiple channels (3-4 maybe?), but I don't think ultra low voltage or ultra high frequency stuff would be necessary.
 

ebeowulf17

Joined Aug 12, 2014
3,274
Rigol 1054Z is worth a look. I used one at work and like it a lot (but I'm pretty inexperienced and the only other scope I know is an old, half-broken analog one.) Depending on what you want to scope in a high voltage arc lighter project, you may need to protect your inputs from crazy high voltages or potentially get different probes, but the same would be true for any competing scopes.

https://www.alliedelec.com/product/rigol-technologies/ds1054z/70406816/?gclsrc=aw.ds&&gclid=CjwKCAiA7t3yBRADEiwA4GFlI77MhZd7OVL3l-r2Vwv_i0L0BFFAD3g4pTsM-USn9ksBq7_VrMNmCRoCygEQAvD_BwE
 

Thread Starter

-live wire-

Joined Dec 22, 2017
911
Rigol 1054Z is worth a look. I used one at work and like it a lot (but I'm pretty inexperienced and the only other scope I know is an old, half-broken analog one.) Depending on what you want to scope in a high voltage arc lighter project, you may need to protect your inputs from crazy high voltages or potentially get different probes, but the same would be true for any competing scopes.

https://www.alliedelec.com/product/rigol-technologies/ds1054z/70406816/?gclsrc=aw.ds&&gclid=CjwKCAiA7t3yBRADEiwA4GFlI77MhZd7OVL3l-r2Vwv_i0L0BFFAD3g4pTsM-USn9ksBq7_VrMNmCRoCygEQAvD_BwE
Okay, that looks decent. But what kind of input voltages can it handle? Mains? Higher voltages? Also, how do I tell how many millivolts it will be accurate to? And how does all this change at different frequencies?

From a
 

schmitt trigger

Joined Jul 12, 2010
198
If you are going to handle high voltages, you should get the proper probes.....100X, 1000X, differential.

As a matter of fact, once that you get a collection of good probes, they could be worth far more than the scope itself
 

BobTPH

Joined Jun 5, 2013
2,346
If Sensitivity is listed at 1mV to 10V per division, so full screen would be about + or - 5mV to 50V with a 1X probe and 500V with a 10X probe. They usually come with a switchable 1X 10X probe. If you need more voltage you can get a 100X probe.

Bob
 

ebeowulf17

Joined Aug 12, 2014
3,274
Okay, that looks decent. But what kind of input voltages can it handle? Mains? Higher voltages? Also, how do I tell how many millivolts it will be accurate to? And how does all this change at different frequencies?

From a
The resolution and accuracy both depend heavily on what scale you're running at, which in turn is a function of what voltages you're looking at.

If I remember correctly, it's using 12 bit conversion, meaning there are 4096 possible values for any given data point. The scale can range anywhere from 8mV to 80V. So, at it's most precise, you could potentially have 2uV resolution, but only view a signal of 8mV max p-p. At it's widest range with a 1:1 probe, you can see 80V p-p, but your resolution is about 20mV. If you use that setting with a 10:1 probe, the screen shows an 800V span (though safe operating voltages may be limited by other factors) and you get 0.2V resolution.

Hopefully you see the pattern and the relationship now. Also, keep in mind that I was describing resolution there, not accuracy. Many factors affect accuracy, and it's beyond my skills to give you good info on accuracy, but as a bare minimum you can always assume that whatever your smallest step is, you have at least that much margin of error, usually several times that much.
 

tautech

Joined Oct 8, 2019
89
Hi, I would like to work on more advanced circuits, and to really see what's going on, an oscilloscope could really help. Some projects are a high power HV arc lighter and other stuff with many ICs and such. Where can I get a reliable and good oscilloscope for under $300-400? I would also like multiple channels (3-4 maybe?), but I don't think ultra low voltage or ultra high frequency stuff would be necessary.
Topics like this demonstrate how deep the rabbit hole you are entering really is. Advanced DSO's for normal use are just the first call on your budget while the probes to allow you to safely take measurements can set you back the same amount and more.
HV arc lighters are often 10+KV and it's wise practice to uprate probes to the order of 50% again to protect yourself and instrument.
There are few Differential probes that can operate up there so cheaper options will be HV passive probes. However how far you go down the track of getting a comprehensive set of probes like 100:1, 1000:1 Differential and current probes can all together set you back a good amount more than just the scope ! But at least you can use them on other scopes if you decide to upgrade later so as such they are a one off cost.
Modern DSO's have fairly good max input ratings but double check the capabilities of older CRO's you might be looking at.
Have a squiz at the SDS1202X-E and SDS1104X-E offerings from Siglent.
 

Wuerstchenhund

Joined Aug 31, 2017
189
Hi, I would like to work on more advanced circuits, and to really see what's going on, an oscilloscope could really help. Some projects are a high power HV arc lighter and other stuff with many ICs and such. Where can I get a reliable and good oscilloscope for under $300-400? I would also like multiple channels (3-4 maybe?), but I don't think ultra low voltage or ultra high frequency stuff would be necessary.
Don't waste time on an analog boat anchor. Just gt the Rigol DS1054z, it's <$400 which for a brand new 4ch scope is a steal. All options can be unlocked (google "Riglol"), and the BW can be upgraded to 100MHz.

The resolution and accuracy both depend heavily on what scale you're running at, which in turn is a function of what voltages you're looking at.
No, not really. The accuracy and resolution of a DSO are fixed and determined by the ADC and the timebase. The vertical scale doesn't matter.

If I remember correctly, it's using 12 bit conversion
Nope, it's 8bit, like pretty much all of the other entry level scopes (true 12bit scopes go for >$10k). Which means there are 256 voltage steps only.

Which doesn't matter, as a scope is not a voltmeter, it's a waveform analyzer. If you need high voltage resolution then a suitable voltmeter is a better tool.
 
As a self-taught hobbyist, my first scope was a DSO138 on Aliexpress for €15 fully assembled + incl shipment. Got me started.
Then bought a portable DSO212 which was a minor upgrade.

Last month got a real scope. After first considering a Rigol 1054Z opted for Siglent SDS 1104X-E 100Mhz 4-channel scope which is more recent, and bit more expensive.

If you can afford it go straight for the Rigol, Siglent or similar scope. Then you have quality, useable for a long long time.
 

ebeowulf17

Joined Aug 12, 2014
3,274
Don't waste time on an analog boat anchor. Just gt the Rigol DS1054z, it's <$400 which for a brand new 4ch scope is a steal. All options can be unlocked (google "Riglol"), and the BW can be upgraded to 100MHz.



No, not really. The accuracy and resolution of a DSO are fixed and determined by the ADC and the timebase. The vertical scale doesn't matter.



Nope, it's 8bit, like pretty much all of the other entry level scopes (true 12bit scopes go for >$10k). Which means there are 256 voltage steps only.

Which doesn't matter, as a scope is not a voltmeter, it's a waveform analyzer. If you need high voltage resolution then a suitable voltmeter is a better tool.
Thanks for the 8 bit correction. Honestly that's what I thought I remembered, and what I was originally going to write, but two different websites told me 12 bit, so that's what I wrote.

As for resolution, it has to be affected by vertical scale. How could it not be? If the vertical scale is showing you over 100 volts, and there are only 256 voltage steps, your resolution doesn't even get down to 1/10th of a volt. But if you set the vertical scale to show 8mV, and it's dividing that into 256 steps, your resolution is around 31uV. Maybe this is just a question of semantics and I'm not using quite the right word for it, but there's a huge difference between being able to see sub-millivolt level signals vs just barely seeing 100mV variations. Perhaps I should've used the word precision instead of resolution? Whatever you call it, it's a dramatic difference.
 

Wuerstchenhund

Joined Aug 31, 2017
189
As for resolution, it has to be affected by vertical scale. How could it not be? If the vertical scale is showing you over 100 volts, and there are only 256 voltage steps, your resolution doesn't even get down to 1/10th of a volt. But if you set the vertical scale to show 8mV, and it's dividing that into 256 steps, your resolution is around 31uV.
What I meant was that the resolution (which for most entry level scopes is 8bit) is independent on the vertical scale. Of course, as you wrote that means if the voltage per unit value is bigger then the voltage resolution decreases.

Maybe this is just a question of semantics and I'm not using quite the right word for it, but there's a huge difference between being able to see sub-millivolt level signals vs just barely seeing 100mV variations. Perhaps I should've used the word precision instead of resolution? Whatever you call it, it's a dramatic difference.
If your full scale is 100V, how do you want to visually discern variations in the sub- mV range? Especially on a tiny 240x400 screen (of which not all is used for the graticule)?

For a 100V scale an 8bit scope gives you around 390mV resolution. If you want to see smaller voltage changes then you need to zoom in, i.e. by changing the vertical setting to something showing a smaller full scale voltage. This will then also increase your voltage resolution.

It seems you expect a scope to be something like a precision voltmeter, which it's not.


The Rigol manual shows 12 bit Hi Res mode -
The Hi Res mode isn't a true 12bit mode, it's a simple oversampling/boxcar mode which will also limit the usable BW (and can cause aliasing errors as the analog BW isn't limited).

Most scopes have a similar mode because it's simple (cheap) to implement. It can be useful for some applications but it's not a true 12bit mode (and is unlikely to result in a real 12bit resolution) and doesn't change the fact that the scope is still an 8bit scope.
 

ebeowulf17

Joined Aug 12, 2014
3,274
What I meant was that the resolution (which for most entry level scopes is 8bit) is independent on the vertical scale. Of course, as you wrote that means if the voltage per unit value is bigger then the voltage resolution decreases.



If your full scale is 100V, how do you want to visually discern variations in the sub- mV range? Especially on a tiny 240x400 screen (of which not all is used for the graticule)?

For a 100V scale an 8bit scope gives you around 390mV resolution. If you want to see smaller voltage changes then you need to zoom in, i.e. by changing the vertical setting to something showing a smaller full scale voltage. This will then also increase your voltage resolution.

It seems you expect a scope to be something like a precision voltmeter, which it's not.




The Hi Res mode isn't a true 12bit mode, it's a simple oversampling/boxcar mode which will also limit the usable BW (and can cause aliasing errors as the analog BW isn't limited).

Most scopes have a similar mode because it's simple (cheap) to implement. It can be useful for some applications but it's not a true 12bit mode (and is unlikely to result in a real 12bit resolution) and doesn't change the fact that the scope is still an 8bit scope.
I agree with you on 99% of this now.

I don't expect a scope to be a precision volt meter. The reason that understanding the resolution/precision is important is because there are situations where you're looking at a large scale signal and you want to capture low level noise.

For example, I was looking at the noise injected into the mains by our machine in preparation for EMI testing. The noise is at such low levels compared to the mains voltage that you can't see it on a scope display. Theoretically, if you had 24 bit resolution or something, the underlying data (which you can save to USB stick and read on CSV format) would capture useful data even if it was too small to see on screen, but since the resolution is low, it doesn't. In my case, I created a filter to essentially eliminate the 60Hz mains voltage component, then scoped the filter output and zoomed in to low-volt, or maybe even millivolt scales to view the noise. It worked pretty well - the results weren't perfect, but considering I was working with a <$400 scope and about $5 worth of homemade filter, my test results tracked shockingly well with the actual EMI test results we got later at a professional lab.

Sorry, long tangent there. My point is that when a new user is asking about both very high voltages and very low voltage resolution at the same time, it's worth pointing out that the scope has a vast range of capabilities, but can't do it all at the same time. Otherwise, you might look at scope specs quoting sub-millivolt resolution and think you could view mains waveforms at that resolution.

It was never about getting a precise steady state measurement, it was about seeing small signals superimposed on large signals.
 

Thread Starter

-live wire-

Joined Dec 22, 2017
911
Okay, thank you all. I'll take a look at these recommended scopes and probably come back to this when I'm ready to buy.
 

tautech

Joined Oct 8, 2019
89
My point is that when a new user is asking about both very high voltages and very low voltage resolution at the same time, it's worth pointing out that the scope has a vast range of capabilities, but can't do it all at the same time. Otherwise, you might look at scope specs quoting sub-millivolt resolution and think you could view mains waveforms at that resolution.

It was never about getting a precise steady state measurement, it was about seeing small signals superimposed on large signals.
Well yes in principle but better entry level scopes accommodate exactly this sort of feature as a vertical zoom however absolute accuracy is always limited by the typical +3% vertical accuracy of most DSO's.

SDS2000X Plus series vertical zoom screenshot from another electronics forum:
https://www.eevblog.com/forum/index.php?action=dlattach;topic=218238.0;attach=871694;image
 
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