# Help me buy an oscilloscope

Thread Starter

#### mcardoso

Joined May 19, 2020
221
Hi All,

I've had access to an oscilloscope through work to use in troubleshooting home projects, however I don't think I'm going to have access to it much longer. I'd like to pick up a scope for <$1k that will cover any reasonable use I might have for it. I am currently using a Fluke Scopemeter (4 channel 200MHz, 2.5Gs/s, 10 Kpts/channel memory). It is nice but the software features fall extremely short of a proper bench scope, especially on the memory depth. https://www.fluke.com/en-us/product...loscopes/190-series-ii/fluke-190-ii-190-204-s My uses are primarily AC motor drives, encoders, troubleshooting EMI, and occasionally sequential logic design (CMOS logic). I have done a bit of stuff with microcontrollers and communications, but never anything I have needed a scope for. Recently I've been working on reverse engineering a robot with AC servos and proprietary feedback communications and I was able to develop an interface board to convert the feedback to standard quadrature with commutation. I'm trying to narrow down on what I actually need in a scope and looking for suggestions on what is worth buying. I think I need a 4 channel scope and having one with MSO capability would be a big plus. I'm not sure on bandwidth so I centered my search around 200MHz. I'm unsure what a good value for samples/s or memory depth is. I am currently looking at the Siglent SDS1204X-E (200MHz, 1Gs/s, 14 Mpts memory). Does anyone own this one and can recommend it? Any solid alternatives. It does look like it has an MSO add-on although the hardware and license are expensive. https://int.siglent.com/products-overview/sds1000x-e/ Thanks for the feedback Last edited: #### nsaspook Joined Aug 27, 2009 9,433 It's nice having MSO capability but you really need a big screen scope display to use it effectively with a large number of channels. https://forum.allaboutcircuits.com/threads/blinky-prop-for-comic-con.127266/post-1038815 and you really need to understand what you are looking for to make it useful. https://forum.allaboutcircuits.com/threads/fifo-logic-block-meta-stability.136284/post-1143241 With a 4 channel scope with included decoding IMO you won't be using pure digital MSO that often. https://forum.allaboutcircuits.com/threads/oscilloscope-features.152317/post-1307422 Most of the time I use one of the cheap 24MHz 8 channel USB units for slow speed digital. https://usa.banggood.com/USB-Logic-...GA-Debug-Tool-p-1177821.html?cur_warehouse=CN https://learn.sparkfun.com/tutorials/using-the-usb-logic-analyzer-with-sigrok-pulseview Last edited: #### tautech Joined Oct 8, 2019 236 I am currently looking at the Siglent SDS1204X-E (200MHz, 1Gs/s, 14 Mpts memory). Does anyone own this one and can recommend it? Any solid alternatives. It does look like it has an MSO add-on although the hardware and license are expensive. https://int.siglent.com/products-overview/sds1000x-e/ Disclosure, I'm the NZ agent for these ^ They are a feature packed little box and its little brother the 100 MHz SDS1104X-E is one of our best sellers. Values for$ they are hard to beat. I personally dislike the MSO option due to it being an external box as the form factor of the DSO doesn't permit the MSO circuitry to be incorporated yet it works as it should albeit with additional clutter on the bench.
If your budget can stretch to it a SDS2104X Plus might be a better choice and although only released this year they are proving to be very popular. While the SDS2104X Plus is only sold as a 100 MHz DSO I personally have tested its BW and found the -3dB point ~185 MHz.
Happy hunting.

Thread Starter

#### mcardoso

Joined May 19, 2020
221
It's nice having MSO capability but you really need a big screen scope display to use it effectively with a large number of channels.
https://forum.allaboutcircuits.com/threads/blinky-prop-for-comic-con.127266/post-1038815

and you really need to understand what you are looking for to make it useful.
https://forum.allaboutcircuits.com/threads/fifo-logic-block-meta-stability.136284/post-1143241

With a 4 channel scope with included decoding IMO you won't be using pure digital MSO that often.
https://forum.allaboutcircuits.com/threads/oscilloscope-features.152317/post-1307422

Most of the time I use one of the cheap 24MHz 8 channel USB units for slow speed digital.
https://usa.banggood.com/USB-Logic-...GA-Debug-Tool-p-1177821.html?cur_warehouse=CN
https://learn.sparkfun.com/tutorials/using-the-usb-logic-analyzer-with-sigrok-pulseview
It is my understanding that these scopes have some way of attaching a larger screen, perhaps through the web interface. Although who knows if the scope renders at a higher resolution than the native 640x480 or if the framerate is passable. I could also be totally wrong about this.

I doubt I would often use the MSO, but I would have killed for 8-10 channels instead of 4 on my last project. It was all digital, so the MSO would have been great.

I like that USB logic analyzer you linked. What speed of circuit would you trust it to help you debug? I don't have any projects specifically in mind at the moment, but my last one ran at 8 MHz and I was trying to capture metastability events at the circuit inputs due to a clock domain crossing. I would question if the 24MHz analyzer could sample fast enough to catch the occasional failure in the circuit.

Disclosure, I'm the NZ agent for these ^

They are a feature packed little box and its little brother the 100 MHz SDS1104X-E is one of our best sellers. Values for $they are hard to beat. I personally dislike the MSO option due to it being an external box as the form factor of the DSO doesn't permit the MSO circuitry to be incorporated yet it works as it should albeit with additional clutter on the bench. If your budget can stretch to it a SDS2104X Plus might be a better choice and although only released this year they are proving to be very popular. While the SDS2104X Plus is only sold as a 100 MHz DSO I personally have tested its BW and found the -3dB point ~185 MHz. Happy hunting. I don't mind the clutter so much I think. Unsure if I'd buy the MSO add on right out of the box, but it is nice to know I can. What does the SDS2104X+ do beyond the SDS1204X-E that justifies the cost upper and reduced advertised bandwidth? #### bloguetronica Joined Apr 27, 2007 1,521 What would be the maximum frequency you need to measure? Do you need to be precise? How many samples do you need in memory? I would guess that a 60MHz scope would fit your needs, or even a 20MHz one. Are you on a budget? As for the relation between input frequency and samples per second, you want a scope that has at least a MSa/s figure five times bigger than your maximum input frequency. In fact, ten times would be ideal. For instance, 20MHz->200MSa/s or 100MHz->1GSa/s. #### nsaspook Joined Aug 27, 2009 9,433 It is my understanding that these scopes have some way of attaching a larger screen, perhaps through the web interface. Although who knows if the scope renders at a higher resolution than the native 640x480 or if the framerate is passable. I could also be totally wrong about this. I doubt I would often use the MSO, but I would have killed for 8-10 channels instead of 4 on my last project. It was all digital, so the MSO would have been great. I like that USB logic analyzer you linked. What speed of circuit would you trust it to help you debug? I don't have any projects specifically in mind at the moment, but my last one ran at 8 MHz and I was trying to capture metastability events at the circuit inputs due to a clock domain crossing. I would question if the 24MHz analyzer could sample fast enough to catch the occasional failure in the circuit. I don't mind the clutter so much I think. Unsure if I'd buy the MSO add on right out of the box, but it is nice to know I can. What does the SDS2104X+ do beyond the SDS1204X-E that justifies the cost upper and reduced advertised bandwidth? Yea, it's limited by the actual scope video resolution. Here I have a external LCD on the right connected to the TEK scope VGA output on the left. Having it display next to the computer screen is the main advantage while working of software that changes the signals the MSO is decoding. The USB logic analyzer would have problems finding high speed glitches but it's less than$20 bucks.

I've not used this one but it's a possibility for higher speed debugging.

The probes on the unit seem unlikely to handle 100MHz signals very well.

#### tautech

Joined Oct 8, 2019
236
It is my understanding that these scopes have some way of attaching a larger screen, perhaps through the web interface.
Correct.
Example vid I did a few years back soon after the X-E were released:

What does the SDS2104X+ do beyond the SDS1204X-E that justifies the cost upper and reduced advertised bandwidth?
The list is quite long but the main advantages for SDS2104X+ vs SDS1204X-E are:
2 GSa/s
200 Mpts memory.
2 Mpts FFT
10" touch and mouse capable display.
BW upgrade options to 500 MHz.
Probe sense capability.
Internal 50 MHz AWG.
Internal MSO (no box on the bench)
Better MSO probe set.
More decode protocols supported.
Greater analysis feature set.

Currently there is an SDS2000X+ Options promo package where all options except MSO and BW upgrades are free with a new purchase.
IMO if you can stretch your budget to a Plus model there is every likelihood you may never need to replace it as they are so well featured packed. This is not to say the X-E isn't a good scope hover it's not in the same class as the Plus.
If I didn't already have a SDS5054X as my personal DSO I would have one of these instead, however my everyday scope is a SDS1104X-E.
Kinda lucky I guess when my demo units also serve as my personal scopes.

Thread Starter

#### mcardoso

Joined May 19, 2020
221
What would be the maximum frequency you need to measure? Do you need to be precise? How many samples do you need in memory? I would guess that a 60MHz scope would fit your needs, or even a 20MHz one. Are you on a budget?

As for the relation between input frequency and samples per second, you want a scope that has at least a MSa/s figure five times bigger than your maximum input frequency. In fact, ten times would be ideal. For instance, 20MHz->200MSa/s or 100MHz->1GSa/s.
So I mostly do mechanical and industrial electrical work. Motor drives, encoders, etc. so usually <1MHz. 8MHz is the fastest speed I've ever done for a PCB design. I am often looking for EMI and glitches on signals, so that tends to require more sampling and bandwidth. I've been using a 200MHz 2.5Gs/s scope for a while and probably haven't pushed it hard at all. My biggest gripe was the 10,000 pts memory depth, shared for all channels. Really limited the length of signal you could record and analyze. Plus it only had very basic triggering and analysis functions.

I would be using it for hobby purposes, so your occasional microcontroller measurements and troubleshooting my control panels I build for various machines. Budget would be <$1000 unless someone convinced me that what I could get for that price would not meet my needs. The list is quite long but the main advantages for SDS2104X+ vs SDS1204X-E are: 2 GSa/s 200 Mpts memory. 2 Mpts FFT 10" touch and mouse capable display. BW upgrade options to 500 MHz. Probe sense capability. Internal 50 MHz AWG. Internal MSO (no box on the bench) Better MSO probe set. More decode protocols supported. Greater analysis feature set. Currently there is an SDS2000X+ Options promo package where all options except MSO and BW upgrades are free with a new purchase. IMO if you can stretch your budget to a Plus model there is every likelihood you may never need to replace it as they are so well featured packed. This is not to say the X-E isn't a good scope hover it's not in the same class as the Plus. If I didn't already have a SDS5054X as my personal DSO I would have one of these instead, however my everyday scope is a SDS1104X-E. Kinda lucky I guess when my demo units also serve as my personal scopes. Man, sounds great. I think I'm just going to have a hard time stomaching the$1400 cost. I share this budget with my machine shop budget and that could get me some nice machines

What is the input voltage limitation on either the SDS2000X+ or the SDS1000X-E scopes? I see the Cat III/IV rating on portable scopes, but I don't see them on bench scopes. Maybe it is all based on probes? I would be measuring up to about 650-700VDC at times but typically 240VAC/325VDC.

#### tautech

Joined Oct 8, 2019
236
Man, sounds great. I think I'm just going to have a hard time stomaching the $1400 cost. I share this budget with my machine shop budget and that could get me some nice machines What is the input voltage limitation on either the SDS2000X+ or the SDS1000X-E scopes? I see the Cat III/IV rating on portable scopes, but I don't see them on bench scopes. Maybe it is all based on probes? I would be measuring up to about 650-700VDC at times but typically 240VAC/325VDC. CAT ratings are related to use case and the proximity of mains ground where with a portable scope has no mains supply they are able to operate more safely in higher CAT environments. Bench equipment OTOH is normally used on 'appliance' level tasks where their mains supply is more removed and protected from grid supply where the chance of risk of surge/spikes is much lower. Probes are typically rated to 600V and scope inputs to 400V therefore I would strongly recommend the use of 100x probes for all HV and/or mains work for the additional safety factor they offer the user and the test equipment. However when dealing with mains control circuitry and particularly the frequent requirement for your reference connection NOT to be on mains ground becomes a strong argument for the need for at least one differential probe that can offer additional safety when working with elevated voltages. Yes I know, this is another rabbit hole to venture into plus another separate budget in order to do HV stuff safely yet 100/1000x probes, differential probes and current probes can also be used on any further scope you might acquire later. Yet to be reasonably well covered with a range of probes can cost more than the initial price of a scope. Say 100x probe ~$100 ea, Differential probe ~$400 ea and current probes$400 and up ea.

BTW, in the video above I've used 1x, 10x, 100x and 1000x probes all connected to the probe Cal 3V p-p 1 KHz signal.

Thread Starter

#### mcardoso

Joined May 19, 2020
221
@tautech, Thanks again for the very detailed answer! I think that as much as the SDS2000X+ looks amazing, I'm going to have a hard time justifying the price for hobby use at this point in time. I think I'll probably go with the SDS1204X-E. If I do outgrow it, I'll have a much better idea of what I should upgrade to.

Thanks to all for the input!