Need suggestions on entry level oscilloscopes for EE students

Need suggestions on entry level oscilloscopes for EE students
Posted by ModernWires on 20 Oct, 2019 17:04
Hello EEVblog. I'm looking for a cheap (under $500 USD, preferably under $400) digital oscilloscope. What are some important specs or things I should pay attention to when choosing one? I got a crap scope a couple weeks ago with really low memory depth and terrible menu interface. It was quite annoying to use. I have returned it and started looking for a better one for the money. Is the Siglent SDS1102X-C (not the -E model which is a bit more expensive) any good? It seems to me a decent scope for the money. I've heard that the Rigol DS1054Z is a really nice scope. The problem is you need to hack it to get the full 100MHz bandwidth and there always seems to be the risk of the hack not working. Some people have reported that the hack did not work for them for some reason, which makes me a bit hesitant to get the Rigol.

#1 Reply
Posted by bob91343 on 20 Oct, 2019 17:22
You might consider getting a used unit. I have a few excellent oscilloscopes, both digital and analog, that I obtained for very little money on craigslist and at swap meets and ebay.

What do you inted to do with this unit? That will help you decide what features and capabilities are appropriate. A digital unit is, in my opinion, not the best for a first timer. Analog devices have more intuitive interfaces and there are some jobs the digital ones can't do easily, if at all.

#2 Reply
Posted by rstofer on 20 Oct, 2019 17:24
First of all, unlocking the DS1054Z is not a 'hack', it is a known process, used by the factory, to specify the bandwidth of the front end. Dave has a video showing how there is a selection of two capacitors on the input low pass filter. One for 50 MHz and one for 100 MHz. It makes all the sense in the world for Rigol to design the scope this way because all they have to do is unlock the bandwidth and put on a different label. In fact, the options that unlocking affects are those that you pay the dealer to turn on anyway. This is NOT a 'hack'. It is a process used by the factory and the dealers.

Second, there is zero chance that the unlocking fails. If it did, there would be complaints all over the Test Equipment forum - and there aren't.

I bought the scope and unlocked it. It's a 'no brains required' operation. Just use code "DSER" and nothing else.

That said, the newer Siglent SDS1102 1104 1204 X-E scopes probably represent a better value, have a more responsive UI and are just newer. The 1104 can be unlocked to 200 MHz, details elsewhere. I want 4 channels so the 1104 would be my choice. Yes, I would unlock it fairly soon. Maybe not on the first day or even the first week but certainly within the first couple of weeks. Just in case there is a little infant mortality

#3 Reply
Posted by rstofer on 20 Oct, 2019 17:44
If I was a student and realized that I needed both a scope and a signal generator and it would be handy to have a spectrum analyzer for Bode' Plots and FFTs along with a couple of power supplies and a logic analyzer along with a digital pattern generator, I might look seriously at the Digilent Analog Discovery 2. This device was invented for students. The AD2 and a laptop form a lab in a backpack.

https://store.digilentinc.com/analog-discovery-2-100msps-usb-oscilloscope-logic-analyzer-and-variable-power-supply/

I use mine all the time to demonstrate fundamental circuits. I can couple the Waveform device square wave output directly back into a scope channel and display the FFT of a square wave. Or, I can use the same square wave to charge and discharge an RC circuit and display the waveform. Sure, we all know what it SHOULD look like but with a couple of components, we can see what it DOES look like.

You can download the Waveforms software and look at all the gadgets in "Demo" mode. Having the software running on a Raspberry Pi 4B seems pretty cool.

Look at the weird prices on eBay! They're all over the map and even the original version is selling for a lot of money. After graduation, sell the AD2 and buy something that takes more space. In the meantime, you can do your lab work with the AD2 while sitting in a coffee shop.

A lot of folks just want a bench full of boxes and I'm no different. But when it comes to convenience, the AD2 is way above everything else. It doesn't have huge bandwidth but it has more resolution than you're likely to find in a reasonably priced scope. It is definitely NOT a toy! If I were a EE student, it is the first thing I would buy. I would buy the student kit and add whatever other gadgets and parts kits I could afford. The capability is amazing!

A while back I was helping a friend with an FPGA project while enjoying coffee at Starbucks. Here we were, at a small table, with 3 laptops open, two FPGA boards being programmed while sipping coffee. It doesn't get any more 'geek' than that! Alas, I don't think a pair 70+ year old retired EEs can be considered geeks. Too old... People were probably laughing...

#4 Reply
Posted by Shock on 20 Oct, 2019 18:23
I believe the Rigol DS1054Z now ships with all the other features turned on aside from the bandwidth anyway but you might want to check if that is a sticking point for you. As mentioned it's trivial to turn everything on, it's one of the reasons they have sold so many.

I mentioned this just the other day, don't forget you get 4x 150MHz probes with the Rigol as well. It's a really good deal.

#5 Reply
Posted by ModernWires on 20 Oct, 2019 18:39
Quote from: bob91343 on 20 Oct, 2019 17:22
You might consider getting a used unit. I have a few excellent oscilloscopes, both digital and analog, that I obtained for very little money on craigslist and at swap meets and ebay.

What do you inted to do with this unit? That will help you decide what features and capabilities are appropriate. A digital unit is, in my opinion, not the best for a first timer. Analog devices have more intuitive interfaces and there are some jobs the digital ones can't do easily, if at all.

I have considered getting a used analog scope but unfortunately space is really a constraint. I only got a small bench. Old analog ones all seem quite bulky and heavy.

#6 Reply
Posted by rstofer on 20 Oct, 2019 18:49
Quote from: ModernWires on 20 Oct, 2019 18:39
I have considered getting a used analog scope but unfortunately space is really a constraint. I only got a small bench. Old analog ones all seem quite bulky and heavy.
The service technician scopes, like the Tektronix 485, stand upright and can be pushed under the bench. They work well in the upright orientation. Mine has never been on a bench since I bought it about 16 years ago. Cost about $200 for a 350 MHz dual channel scope.

There is no comparison between an analog scope and a modern digital. The single shot feature alone is worth buying a DSO. The number of measurements it can make is another. Analog scopes will be cheap and have a lot of bandwidth for the money but a DSO is on an entirely different level.

#7 Reply
Posted by rstofer on 20 Oct, 2019 18:55
Quote from: blueskull on 20 Oct, 2019 18:47
Ask yourself do you really need serial decoding and all other fancy features?
Absolutely! That's why I bought it. I already had a fast analog scope but I really wanted SPI decoding. I don't like using a logic analyzer, it's just something else to clutter the bench. Besides, if I'm already looking at timing and integrity, I might as well get the decode.
Measurements is another nice feature and the modern DSO makes a LOT of measurements.
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The number 1 problem I had with Rigol is UI speed. The lag is bad, and you need a good temper to use it. Not as bad as some old (DPO/MDO series, not the latest MSO56/58 series) Tek, but still pretty slow.
The Rigol UI is slow and the new Siglents are supposed to be a lot better. Yes, it's a PITA but I spend far more time observing the waveforms than I do adjusting them. As slow as the UI is, it isn't something that I use a high percentage of my 'look at the scope' time. Twice as fast for something I use less than 1/100 of the time just isn't a factor.

Today, I would definitely be looking at the Siglent SDS 1xxx X-E series scopes.

#8 Reply
Posted by ModernWires on 20 Oct, 2019 19:04
Quote from: rstofer on 20 Oct, 2019 17:24
First of all, unlocking the DS1054Z is not a 'hack', it is a known process, used by the factory, to specify the bandwidth of the front end. Dave has a video showing how there is a selection of two capacitors on the input low pass filter. One for 50 MHz and one for 100 MHz. It makes all the sense in the world for Rigol to design the scope this way because all they have to do is unlock the bandwidth and put on a different label. In fact, the options that unlocking affects are those that you pay the dealer to turn on anyway. This is NOT a 'hack'. It is a process used by the factory and the dealers.

What I meant was that normally you need to pay extra to unlock the full bandwidth if I understand it correctly, but there are third party tools that generate keys for you for free. That's why I thought it's some kind of "hack". I don't know if it is possible for them to release a patch or something that prevents future unlocks using the existing unofficial key generators.
The Rigol does seem to offer more features for the same price if I can get the 100MHz upgrade for free.

#9 Reply
Posted by rstofer on 20 Oct, 2019 19:11
Quote from: ModernWires on 20 Oct, 2019 19:04
What I meant was that normally you need to pay extra to unlock the full bandwidth if I understand it correctly, but there are third party tools that generate keys for you for free. That's why I thought it's some kind of "hack". I don't know if it is possible for them to release a patch or something that prevents future unlocks using the existing unofficial key generators.
And yet, after several generations of firmware, the unlocking still works. Do you really think Rigol doesn't know about the key generators? If they had the slightest interest in 'solving' the problem, they have had many opportunities to do it. It's a marketing thing! It costs them the same to make a 50 MHz model as a 100 MHz model. They just take more profit on the 100 MHz versions.
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The Rigol does seem to offer more features for the same price if I can get the 100MHz upgrade for free.
I have the Rigol but today I would probably go for the Siglent SDS1104X-E and unlock it.

#10 Reply
Posted by tautech on 21 Oct, 2019 07:55
Quote from: ModernWires on 20 Oct, 2019 17:04
Hello EEVblog. I'm looking for a cheap (under $500 USD, preferably under $400) digital oscilloscope. What are some important specs or things I should pay attention to when choosing one? I got a crap scope a couple weeks ago with really low memory depth and terrible menu interface. It was quite annoying to use. I have returned it and started looking for a better one for the money. Is the Siglent SDS1102X-C (not the -E model which is a bit more expensive) any good? It seems to me a decent scope for the money.
They're an excellent DSO but beware the X-C I believe is Chinese language UI only.
I checked out the Chinese website and I can't spot any other major differences in functionality compared to the X-E but I'm not convinced I haven't missed something.
http://www.siglent.com/products-overview/sds1000x-c/

The later 4ch X-E/C offer substantially more features than the earlier SDS1002X-E/C models which BTW in western markets we only get the 200 MHz SDS1202X-E.
The SDS1104X-C/E strength is that they use two ADC's with a pair of channels on each so high sampling rates are maintained even with 4 channels in use. This allows them to be a 200 MHz scope and even the tests done on the 100 MHz PP510 probes show no appreciable performance differences to the PP215 200 MHz probes that are supplied with the SDS1204X-C/E models.
Still, SDS1202X-E is my biggest seller closely followed by SDS1104X-E.

#11 Reply
Posted by Dmeads on 22 Oct, 2019 22:28
I second the Analog discovery 2 from digilent. The software works great even on old computers. The power supply can ripple a bit but the scope is awesome.