Sub-80$ (USB) oscilloscope - Page 1
Forum section: electronics / testgear

author: Godot
author_rank: Contributor
timestamp: January 02, 2017, 12:10:09 pm
content: Hello everyone, and Happy New Year!I am looking for an oscilloscope I could use as a completely beginner hobbyist electrician. My budget is, unfortunately, extremely low though, the maximum I could spend is about 80 USD. (Student life sucks...) This implies that the best I could hope for is a USB oscilloscope. (But correct me if I am wrong, I would be really happy with a standalone oscilloscope.)What I found so far is this little guy:SainSmart DDS120, but I didn't really find too much alternative to chose from. The Hantek 6022BE seems to suck software-wise, so I ruled it out. And the DIY oscilloscope DSO138 hardly seems to be more than a toy...I would like to ask you: What oscilloscope would you recommend in this ultra-low price range?(Bonus point if it is standalone or can be used with Android devices)

author: Flenser
author_rank: Regular Contributor
timestamp: January 02, 2017, 01:30:23 pm
content: Another option I'm aware ofhttp://www.pdamusician.com/dpscope/buy_it_ii.htmlIt is slightly above your US$80 limit once you include shipping.

author: pascal_sweden
author_rank: Super Contributor
timestamp: January 02, 2017, 02:15:26 pm
content: Quote from: Flenser on January 02, 2017, 01:30:23 pmThe bandwidth of that oscilloscope is only 2,5 MHz. Way too expensive for the BW which you get.

author: daybyter
author_rank: Frequent Contributor
timestamp: January 02, 2017, 03:01:18 pm
content: There are more and more alternative software solutions available for the 6022be.

author: Gyro
author_rank: Super Contributor
timestamp: January 02, 2017, 05:22:01 pm
content: Quote from: pascal_sweden on January 02, 2017, 02:15:26 pmAgreed. In fact if you delve into the specs its 50Msps sample rate becomes 2Msps single shot, with the 50Msps being only for repetitive waveforms. Rather a shame.P.S. Probes are extra too.

author: MrWolf
author_rank: Regular Contributor
timestamp: January 02, 2017, 05:51:32 pm
content: https://www.picotech.com/oscilloscope/2000/picoscope-2000-specificationsPicoScope 2204A 2ch,10MHz analog, 8kS memory, 100MSa/s RTS,2GSa/s ETS, 1MSa/s USB streaming, 100kHz function gen, 1.548 MHz ARB w 4kS memory$115.00 w/o probesSoftware package same as on 7.5k$ top-of-the line model.35$ more than 80$ but you get function gen / ARB.

author: Godot
author_rank: Contributor
timestamp: January 02, 2017, 06:23:34 pm
content: Quote from: Gyro on January 02, 2017, 05:22:01 pmYeah, I saw that one, but it is worse in pretty much every aspect than the SainSmart. Plus the whole company somehow looks less serious, that device looks like a prototype from 10 years ago...

author: Godot
author_rank: Contributor
timestamp: January 02, 2017, 06:27:27 pm
content: Quote from: MrWolf on January 02, 2017, 05:51:32 pmThat looks pretty. But a bit out of my cap, shame

author: Fungus
author_rank: Super Contributor
timestamp: January 02, 2017, 06:27:48 pm
content: Quote from: MrWolf on January 02, 2017, 05:51:32 pmSo ... about $135 with probes. Plus another (mumble) for shipping.That's about twice the budget. What method are you using to compare prices?Quote from: MrWolf on January 02, 2017, 05:51:32 pmSure, apart from all the disabled stuff:https://www.eevblog.com/forum/testgear/4-channel-dso-with-mask-testing-and-programmability-(lxi-usb-etc-)/msg1104502/#msg1104502

author: Fungus
author_rank: Super Contributor
timestamp: January 02, 2017, 06:32:35 pm
content: This is a tough decision. Everything in this price range is horrible.Get a DSO138. It's a toy, yes, but it works for low frequency stuff, it's better than no oscilloscope at all, you only spent $20andyou get to practice your soldering.

author: MrWolf
author_rank: Regular Contributor
timestamp: January 02, 2017, 06:36:32 pm
content: Quote from: Fungus on January 02, 2017, 06:27:48 pmWell sometimes its worth wait a while and/or be creative. Probes can be found cheaper.Quote from: Fungus on January 02, 2017, 06:27:48 pmYou mean multi-channel mask that I confirmed working in same thread (on out of production 2000)?

author: Gyro
author_rank: Super Contributor
timestamp: January 02, 2017, 06:55:57 pm
content: Maybe you should save up a bit more and read the two most recent <$100 scope threads...https://www.eevblog.com/forum/testgear/old-analog-or-usb-oscilloscope-need-advice/https://www.eevblog.com/forum/beginners/best-oscilloscope-under-$100-cad/

author: mtdoc
author_rank: Super Contributor
timestamp: January 02, 2017, 07:01:25 pm
content: Quote from: Gyro on January 02, 2017, 06:55:57 pm$100 CAD currently = $74.4 USD so the second thread will answer the question. (assuming the OP means $80 USD)

author: rstofer
author_rank: Super Contributor
timestamp: January 02, 2017, 07:07:35 pm
content: I have a DSO138 kit that my grandson is assembling. I bought it specifically for watching slow moving analog signals from my analog computer. Now all I need to do is wait on him to finish the soldering.I have no illusions that this thing is any kind of oscilloscope.

author: Godot
author_rank: Contributor
timestamp: January 02, 2017, 07:46:37 pm
content: Quote from: mtdoc on January 02, 2017, 07:01:25 pmMost of the replies there recommends finding an used analog oscilloscope. I was thinking about it (actually I could get a Russian H3013 for about 30$), but since I do not need to be extremely accurate, aren't I better off with an USB digital one that does all the calculations (rms, freq, FHT etc.) for me in moments? Not to mention the size, and the fact it is not 20 years old...But the Owon vds1022 worths a look, the displayed waveform looks much more stable than the SainSmart's on youtube videos.

author: Fungus
author_rank: Super Contributor
timestamp: January 02, 2017, 09:53:22 pm
content: Quote from: rstofer on January 02, 2017, 07:07:35 pmIt displays a graph of voltage against time. That makes it an oscilloscope.It has a very limited number of voltage ranges, horizontal timebases, etc., but it definitely shows voltage against time.What do you want for $20?

author: rstofer
author_rank: Super Contributor
timestamp: January 02, 2017, 10:35:18 pm
content: Quote from: Fungus on January 02, 2017, 09:53:22 pmMy signals are low and slow. -10V to +10V in 2 seconds or 0.2 seconds when using the 10x input. I don't need much of a scope for this.I really bought it as a soldering exercise for my grandson. I also ordered a cheap signal generator for basically the same purpose.And a couple of AM/FM radio kits.Nothing serious, just soldering practice.

author: vk6zgo
author_rank: Super Contributor
timestamp: January 03, 2017, 06:02:37 am
content: Quote from: Godot on January 02, 2017, 07:46:37 pmThe size difference becomes less important when you realise how much room the necessary laptop takes up!I don't have a USB DSO.or indeed,any type of DSO,but the results I've seen for cheap USB ones on Youtube & other places are fairly underwhelming.Having an inadequate instrument then dressing it up with automatic measurements is a bit like putting lipstick on a pig.The old Russki will probably be a bit crusty,but if it works,you will be surprised how little need you have to be "spoon fed" the measurements.

author: Godot
author_rank: Contributor
timestamp: January 03, 2017, 07:08:43 am
content: Quote from: vk6zgo on January 03, 2017, 06:02:37 amConsidering I am a full amateur, I am still not convinced that I'd be better off with an used analog. I understand that these oscilloscopes are not too accurate, but I don't see how big problem would this be to me, I still get the waveform and the approximate values of it's parameters. I do not need to be super accurate. And apart from that, these are used and old devices that may fail, and I probably won't be able to repair them with my current (lack of) expertice.With this in mind, I am currently deciding between the Owon vds1022 I could buy for 77$ from eBay (and leaning to do so), and two analog 20MHz one on a local portal, both for around 80 USD:Mitek MK4200andRFT EO 213. (Non-English links, sorry)

author: Gyro
author_rank: Super Contributor
timestamp: January 03, 2017, 09:39:10 am
content: I'm not going to comment on the choice of an analogue vs USB digital, but in a contest between the Sainsmart, Hantek and Owon then the VDS1022 is definitely the one to go for (unless you can afford the USB isolated 'i' version). It has a proper 'scope' processing front-end rather than just and ADC and micro, this demands far less from the USB speed and S/W to achieve better performance (screen update rate etc.). $77 (probes included) sounds like a win for your $80 limit. That's $3 left to spend on 'student food'!

author: rstofer
author_rank: Super Contributor
timestamp: January 03, 2017, 08:26:30 pm
content: Quote from: Godot on January 03, 2017, 07:08:43 amHow accurate can you read the graticule anyway? So, 3.3V is maybe 3 divisions and 1/3 of another. How do you interpolate that 1/3? You just couldn't tell if it is 3.2 or 3.4. Does it matter? You measure voltage with a DMM, you get approximate answers with a scope. Measuring frequency on an analog scope is even more iffy. It seldom turns out that the frequency is an exact sub-multiple of the sweep speed.I think of the scope as a qualitative instrument, not a quantitative instrument. Sure, I can make some measurements on an analog scope but, really, most of them are based on a calibrated eyeball. Which is aging...The DSOs are fantastic because they give you measurements that you would otherwise have to interpolate by eye. Is it a big deal? Well, not if the choice is nothing. I have been using a $200 Tek 485 for the past 12 years and everything I built got done sooner or later. Yes, I like my Rigol DS1054Z but I'm not going to toss a 350 MHz analog scope just yet.If what you can afford is a used analog <whatever> and the thing appears to work, go for it. There'll be time to upgrade later.Yesterday, the DSO138 LCD scope was mentioned in passing. I finally have mine running and it's pretty cute. I haven't had time to play with it but maybe later this afternoon.

author: Gyro
author_rank: Super Contributor
timestamp: January 03, 2017, 09:03:29 pm
content: Quote from: rstofer on January 03, 2017, 08:26:30 pm'Cute' is exactly the word I used when I finished mine, the screen looks just like a real scope, just tiny.

author: daybyter
author_rank: Frequent Contributor
timestamp: January 04, 2017, 01:20:26 am
content: http://www.stm32duino.com/viewtopic.php?t=107I think with current prices, it is more like a 5$ scope now...

author: Godot
author_rank: Contributor
timestamp: January 04, 2017, 01:36:29 pm
content: Quote from: rstofer on January 03, 2017, 08:26:30 pmI get your point, and if I could get a 350MHz analog for this price I wouldn't hesitate. But why would I choose a 25MHz used analog over a 25MHz brand-new USB oscilloscope (apart from looking better)? The Owon seems to be better than the usual DSOs in this price range, and it seems to be pretty stable: youtube.com/watch?v=gGOZ9PCVV_A(Could someone tell me how to disable the Youtube video insertion?...)

author: Godot
author_rank: Contributor
timestamp: January 04, 2017, 01:54:08 pm
content: Quote from: daybyter on January 04, 2017, 01:20:26 amHmm, sounds cool...

author: rstofer
author_rank: Super Contributor
timestamp: January 04, 2017, 03:48:31 pm
content: Quote from: Godot on January 04, 2017, 01:36:29 pmYou wouldn't!I don't know anything about the Owon USB scopes but I didn't see one that is sub $80. Still, $105 isn't bad for a 25 MHz scope.

author: vk6zgo
author_rank: Super Contributor
timestamp: January 05, 2017, 12:58:06 am
content: Quote from: Godot on January 04, 2017, 01:36:29 pmOne thing:- A 25MHz Analog Oscilloscope is just that,no matter what the time/div setting.DSOs reduce their sampling rate when they are trying to look at long time intervals (20ms or so),because they lack memory depth.In DSOs of the DS 1054Z class & above,this isnota problem,as the reduction is usually not enough to cause "aliasing",but with very old orvery cheapDSOs this is a real problem if you need to look at complex signals at such timebase settings.A classic test,which we used to disconcert the Tek & HP reps back in the day,is to try to look at a PAL video signal atfield rate (50Hz).This signal contains content up to 5MHz,which the early DSOs could not reproduce at long time/div settings due to their reduced sample rate at such settings .Some of them even had trouble with video atlinerate (15.625 kHz),with the colour burst signal at 4.433MHz reproduced as a bit of a "wiggle",having no relationship to the correct burst shape.The cheap DSOs have the same problem due to cost concerns.I've seen screenshots proudly posted on the internet by someone showing off the performance of the latest "el cheapo" DSO,which exhibit this behaviour.That said,no,I would not pay 80USD for either of the analog 'scopes you linked to---this equates to about $A111,which is about twice what I would pay for what are fairly unsophisticated instruments,lacking delayed timebase & other refinements.If you could pick up a Tek,HP,or Philips with those facilities for 80USD,I would recommend you do so.On the other hand if you are certain you willneverneed to look at high frequency signals using a slow timebase speed,then go for the USB 'scope.If you are not so sure,get an analog,or save up for a Rigol or Siglent bench DSO.

author: Godot
author_rank: Contributor
timestamp: January 07, 2017, 02:43:17 pm
content: Thank you all for the help. At the end, I decided to buy the Owon VDS1022 USB oscilloscope. (72€on ebay, pretty good price) I was thinking on what vk6zgo said, but I think I can live with it. When I will have to do such analysis, I plan to already have a decent oscilloscope

author: MrWolf
author_rank: Regular Contributor
timestamp: January 07, 2017, 09:46:40 pm
content: Quote from: vk6zgo on January 05, 2017, 12:58:06 amTo be more specific. You could only look at general shape of the signals in Rigol when zoomed in. And not do meaningful horizontal measurements but with cursors. So its a big question if 1.2kS screen buffer and large main memory or lets say 100k total buffer is better choice. I would probably also pick OwonGotta test it sometime.

author: Gyro
author_rank: Super Contributor
timestamp: January 07, 2017, 10:22:56 pm
content: Not that it makes a major difference, but the buffer size on the VDS1022 is 5kS, every little helps.

author: MrWolf
author_rank: Regular Contributor
timestamp: January 07, 2017, 11:07:52 pm
content: Quote from: Gyro on January 07, 2017, 10:22:56 pm5k not that bad. If 20ns div optimal for 5MHz, can still stay in game until 20us div. 3 orders. Line rate ok. Plenty for money.BTW is there some other practical app besides video or some long digital transmission where would need to record at 20ms but analyze at 20ns?Overall I like the concept as good "torture test" for scope.

author: Godot
author_rank: Contributor
timestamp: January 09, 2017, 01:01:25 pm
content: Quote from: MrWolf on January 07, 2017, 11:07:52 pmI am also interested in this