need an oscilloscope on a very low budget - Page 1
Forum section: electronics / beginners

author: sx57
author_rank: Contributor
timestamp: December 04, 2022, 09:50:58 pm
content: hello dear friendsI want to make a web site about cables and chargers for cell phones like apple,Samsung and etc.As you know modern phones use switched-mode power supply chargers capable of power delivery or quick charge and other fast charge standards.I wanted to review such chargers, specially their output quality ,parameters like ripple and noise that need an oscilloscope.I live in Iran and everything is very pricey under heavy sanctions and I have about 60 dollars budget .so I can buy hantek PSO 2020.Do you think this oscilloscope can measure ripple and high frequency noise well enough considering that switching frequency of modern chargers is very high?Is the sampling rate enough? if I am right the true sampling rate of this model is 48ms not 96ms.maybe even lower.What about the bandwith do you trust the hantek in that regard?There is also hantek 6022BE with two channels and no ac coupling . don’t know if that is a better option.I found some owon models for about 2 to 3 times the price and I could not afford them.Do you think I must save more money and buy one of them? i mean owon rds 1021 or 1022.My most important need is to verify if the chargers output good quality dc current for the phones. if you think that I have to measure other parameters other than ripple and noise please notify me.Thank you all .

author: wasedadoc
author_rank: Super Contributor
timestamp: December 04, 2022, 10:49:17 pm
content: Note that m is an abbreviation for milli which is a thousandth (1/1000) whereas M is an abbreviation for Mega which is a million (1,000,000).

author: Manul
author_rank: Super Contributor
timestamp: December 04, 2022, 11:30:31 pm
content: I would also build an electronic load, prefferably variable. Using phone as a load is not very scientific and may lead to various inaccuracies. Decent multimerer is a must for accurate voltage measurements. You may want to measure voltage at maximum load. That indicates cable quality (voltage drop). Crappy cables might drop a lot, which is also a sign that they are likely less mechanically robust and may break easily.Now the noise measurement is more difficult. I recommend you to study the subject. You should use ground spring, not ground clip. It will depend what point you probe. Probably you want some nominal bypass capacitor directly at probing point. You might want to use common mode filter, because your measurements may get polluted by common mode noise. Is 20Mhz bandwidth enough? Borderline. 20mV per division is certainly not very sensitive. Is it on 10X or 1X? If it is 1X, then at 10X it will be 200mV per division, beware!I would also test isolation voltage of the chargers. This would be destructive and requires special equipment. But knowing that cheap chargers regulary shocks and kills people, that is really relevant test.

author: sx57
author_rank: Contributor
timestamp: December 05, 2022, 08:24:30 am
content: Thank you.very helpful points .what about oscilloscope models i mentioned or any other suggestions?

author: MrAl
author_rank: Super Contributor
timestamp: December 05, 2022, 01:54:25 pm
content: Quote from: sx57 on December 05, 2022, 08:24:30 amProbably want to stay away from some models.Look for the thread in the Test Equipment section with title "What brand name oscilloscope" or something like that there is a big discussion about scopes and that some are not very good.Here it is:https://www.eevblog.com/forum/testgear/best-brand-name-for-an-oscilloscope/

author: sx57
author_rank: Contributor
timestamp: December 05, 2022, 01:57:33 pm
content: thanks mate i will look into it.

author: Gyro
author_rank: Super Contributor
timestamp: December 05, 2022, 02:09:36 pm
content: Certainly the VDS1022 (preferably the 1022I isolated version) over the 6022BE, it performs much better, and [Edit: as you say,] the 6022BE doesn't have AC coupling capability, so it wouldn't be possible for it to display low level ripple superimposed on the DC supply.More of an issue with cell phone chargers is safety rather than ripple. DiodeGoneWild shows many teardowns of electrically unsafe adapters (you may have some difficulty with his accent)...https://www.youtube.com/channel/UCQak2_fXZ_9yXI5vB_Kd54g/videos

author: xmris
author_rank: Contributor
timestamp: December 05, 2022, 06:47:21 pm
content: thanks mate for this link... real epic videos there like SMD soldering using ... soldering gun :-}

author: sx57
author_rank: Contributor
timestamp: December 05, 2022, 08:23:09 pm
content: Thanks alot mate.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: December 06, 2022, 06:48:02 am
content: I have no opinion which oscilloscope you should buy, but would like to say that AC coupling is not difficult to make yourself. This is the input section of a Textronix 465 100MHz oscilloscope. The AC coupling is provided by C3 in series with the input signal. You could add this externally since it doesn't matter much where in the input path it is placed. It doesn't need to be 0.19uF: 0.1uF should be plenty for looking at 50Hz since it would be like a 33Kohm resistor.The operation of the selector switch isn't easy to understand from the schematic, but in the middle "GND" position it discharges C3 through R3 in case a high voltage DC charge has accumulated in C3. This is to prevent the voltage from being applied to the input when the switch is further turned to the "DC" position. R4 prevents the capacitor from accumulating a charge when the switch is in the "DC" position.

author: sx57
author_rank: Contributor
timestamp: December 06, 2022, 08:56:11 am
content: Quote from: Paul Moir on December 06, 2022, 06:48:02 amthanks a lot friend. this way i can make one if i buy 6022be. i think 6022 is not gonna do what i need so i am thinking on increasing the budget. i am doubtful about pso 2020 too. hope others share their suggestions and experiences.

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: December 06, 2022, 10:41:34 am
content: At some point they lent me a hantek 6022be or BL I don't remember well, it had a built-in logic analyzer, for hoobist use it works well, I have seen that they also use it in automobiles, the bad thing I see, few trigger modes, it has no coupling CA (you can make a homemade one), in windows 7 it works fine, in windows 10 it was labeled, we are talking about a 60 dollar team, but to begin with it works,in spanishEn algun monento me prestaron uns hantek 6022be or BL no recuerdo bien, tenia analizador logico incorporado, para el uso hoobista funciona bien, lo he visto que tambien lo usan en automotores, lo malo que le veo, pocos modo de trigger, no tiene acoplamiento CA(se puede hacer uno casero), en windows 7 va bien, en el windows 10 se me tildaba, estamos hablando de un equipo de 60 dolares, pero para empezar funciona,

author: tatel
author_rank: Frequent Contributor
timestamp: December 06, 2022, 12:40:58 pm
content: I'm not an expert at all, but I have many times read on this forum that 20mV/div is "useless to see PSU ripple/noise". Not sure if that really holds true. 20mV/div is the published input sensitivity of hantek PSO 2020. Hantek 6022BE has 10mV/div input sensitivity (about $70 on aliexpress). Gyro's recommendation, OwonVDS1022 has a published input sensitivity of 5 mV/div ( $85 on aliexpress for the non-isolated version, $116 for the isolated version VDS1022i) I don't think your budget will allow for any oscilloscope with 1 mV/div input sensitivityI think Owon VDS1022(i) is probably better for you than Hantek 6022BE for a little price difference. Also, Hantek is well known for their dubious specs.You could be interested in Gyro's excellent thread about Owon VCS1022ihttps://www.eevblog.com/forum/testgear/owon-vds1022i-quick-teardown-(versus-the-hantek-6022be)/Dave's video about "How To Measure Power Supply Ripple & Noise" has very good info and tips about what you are aiming at, I think

author: BillyO
author_rank: Super Contributor
timestamp: December 06, 2022, 04:13:11 pm
content: @sx57.The Hantek 6022BE is not a great scope. There are huge limitations and it does not even meet it's rate 20MHz bandwidth. It's is more like 15MHz at the very best.However, the Hantek 6074 is a much, much better scope. Yes, I know it is $150, but compared to the 6022BE is is worth it.Here are a short list of the advantages:Has AC couplingHas 4 channelsExceeds it's bandwidth rating ** (see below)Comes with two x1/x10 probes and two alligator clip cables.1GSa/s - (20 times better than the 6022BE)More trigger modes (edge, pulse, video, alternate)Greater vertical sensitivity range 2mV to 10V vs 20mV to 5V** When used with only 1 channel enabled it has 250MHz bandwidth!! This decreases as you add channels until you have all 4 enabled where it still delvers better than 80MHz bandwidth.My advice is to save up a few more $$ rather than throw your money away on the 6022BE

author: sx57
author_rank: Contributor
timestamp: December 06, 2022, 08:48:49 pm
content: thanks a lot for your great assistance my friends. i no longer consider 6022be as it has a very bad reputation as you have clearly pointed out. i will save money to buy a better scope like owon or hanek 6074.i am still interested to hear more from you about hantek 6074bd,OWON VDS1022 or any other suggestions you may have.OWONVDS1022 is between 120 to 160 dollars here while hantek is about 220 to 256 dollars.do you think the owon is good enough or should i save for the hantek 6074bd or something else?

author: BillyO
author_rank: Super Contributor
timestamp: December 06, 2022, 11:37:14 pm
content: I was mentioning the 6074BC. It is here for $153:https://www.ebay.ca/itm/291742464153The Owon shares a lot of the issues with the Hantek 6022 (2-ch, low bandwidth, low sampling rate). I think you will grow out of it quickly.

author: donlisms
author_rank: Frequent Contributor
timestamp: December 06, 2022, 11:40:49 pm
content: An alternative to finding an oscilloscope that can directly interpret your power supply "signals" would be to use an appropriate amplifier, to make the signal easy for the oscilloscope to show. I think an AC coupled amplifier with sufficient gain, even a simple one, could do the job. Lots of gain for the ripple and noise, no gain for the DC. This preamplifier should be low noise itself, of course!

author: tatel
author_rank: Frequent Contributor
timestamp: December 07, 2022, 01:37:54 am
content: Now you are about to get analysis paralysis. It's knocking at your door. Don't let it get in.USB scopes are recommended only when you can't afford an entry-level 4 channel benchtop scope or have some special portability needs. If that's the case, it seems most people think Owon VDS1022 is the worthiest one. There's no point purchasing a "more capable" USB scope if a cheaper one can do what you need it to do. The "more capable" one will remain always an USB device and it will always have the shortcomings of an USB scope.Please note I am lucky enough to have one of these benchtop 4 channel scopes in the $500 range, so I don't have any user experience with USB scopes. I think Owon VDS 1022 could do all you need it to do, but you'll have to check it yourself.Now, to make your decision, there are some pointers:Dave's video explains, much better than most of us could ever do, what you need to measure PSU ripple/noise. Do you think VDS1022 is able to do what Dave says in that video? Check the specs. Has it enough bandwidth? Enough channels? Enough sensitivity?Go to Gyro's thread. Is people happy with Owon VDS1022? What do they say about how it works? How do they compare it with other USB devices? You should search the forum for threads about the different candidates. Only you know what device you can really afford.If you read Gyro's thread, you'll find there is people who purchased the non-isolated version and converted it to the isolated version afterwards. It doesn't seem to save much money, but if your budget is so tight, it could allow you to make your initial expense lower while retaining the ability to upgrade in the future. Many purchased the non-isolated version, seem to be happy with it, and do not feel any need to upgrade to the isolated version.You'll find also that many owners of Owon VDS1022 are using an unofficial software which seems to solve some shortcomings the official one has, seehttps://github.com/florentbr/OWON-VDS1022Owon VDS1022 is Dave's recommendation if you have to put together an electronics lab for just $300 in all. See:See what Dave says about USB scopes when you don't have to squeeze your wallet so much (go to 3:06 if you want but the whole video is worth watching):You just need some hours of reading posts and to watch some videos, not just about VDS1022, but also about any other device you could be interested in. I think you have now enough pointers to do an informed decision, which can only be made by you.It would be a little bit bizarre if, being you the prospective buyer, would be also you who doesn't read the relevant threads nor watch the dedicated videos, don't you think so?

author: BillyO
author_rank: Super Contributor
timestamp: December 07, 2022, 02:33:47 am
content: Quote from: tatel on December 07, 2022, 01:37:54 amThe fact is, the Owon VDS1022 ismaybethe "worthiest" 25MHz USB scope. Nothing more. There are in fact USB scopes, with all the shortcomings (?) that implies, that will put the very best $500 benchtop 4 ch. scope to utter shame. Just check out the Pico Technology 9300 or 9400 series USB scopes .. for fun. They run about $40,000.What it boilsdown to is, any scope is better than no scope. However, "just good enough" is usually notthe way to go as your needs are likelyto change. It is always better to go with something that somewhat exceeds your minimum requirements so you are not in a position to have to trade up in short order.But I agree with our learned friend. Check out some user discussions, reviews on-line and youtube videos before making a final decision.

author: sx57
author_rank: Contributor
timestamp: December 07, 2022, 10:30:26 am
content: thanks everyone for your help.@tatel:i had seen dave's excellent video about how to measure ripple and i had read about smps ripples and noise. but in the end i got a little confused, on the one hand i have read that 20 mhz must be selected for ripple and noise measurement and on the other hand there was a thread that people said that there may be a mess way beyond 20mhz that we will miss if we choose 20mhz bandwidth. i also learned that 5mv/div is enough for me because a good smps should have around 10mv ripple so lower than 5mv is not gonna be that important but i was worried that owon may be lying about it's specs. i was also confused about real bandwidth needed because if 20 mhz is not enough, why should we limit it to 20 mhz to filter he higher bandwidth noise? that's when i thought asking good people of eevblog will help me to find a good solution and they will tell me if the bandwidth is low or owon is lying like hantek or any other matter i need to know. i am gonna watch the other videos posted here.

author: sx57
author_rank: Contributor
timestamp: December 07, 2022, 10:32:14 am
content: Quote from: BillyO on December 06, 2022, 11:37:14 pmunfortunately,6074c is not available in iran

author: Doctorandus_P
author_rank: Super Contributor
timestamp: December 08, 2022, 08:51:33 am
content: With USB scopes, the usability of the software is a big concern. Picotech likely has the best software and their most affordable scope is the 2204A for EUR140, which is also in your price range.https://www.picotech.com/oscilloscope/2000/picoscope-2000-overviewSome of the entry level handheld scopes are also in that price range. Something similar to a Hantek 2D72 or OWON HD272S.

author: Gyro
author_rank: Super Contributor
timestamp: December 08, 2022, 10:29:01 am
content: I doubt whether the Pico will be available to the OP.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: December 08, 2022, 02:22:46 pm
content: Quote from: Gyro on December 08, 2022, 10:29:01 amSame here, but If I don't post it because of my doubt then the door is already closed beforehand.

author: tatel
author_rank: Frequent Contributor
timestamp: December 08, 2022, 03:20:48 pm
content: Quote from: BillyO on December 07, 2022, 02:33:47 amYou are right, of course. I just disregard top ranking USB scopes because OP says he has a really tight budget. AFAIK, any USB scope in that price range will probably suffer from USB bottleneck. That Owon seems to be able to do most of the work within the device itself, so it seems to work better than others, while using just full speed USB. Other devices using high speed USB 2 (so theoretically 40x faster) seem to work worse. Please correct me if I'm wrong, I'm always willing to learn.My point is: should OP wait until enough money is saved to get a tool more than good enough, his project would have to wait also. Getting a good enough tool as soon as posible, he can go ahead with his project sooner rather than later. And he can always continue savig after the purchase, while having a working project.@sx57 I'm guessing this stuff is heavily taxed in your country?

author: mwb1100
author_rank: Frequent Contributor
timestamp: December 08, 2022, 05:08:24 pm
content: Quote from: tatel on December 08, 2022, 03:20:48 pm@sx57 has mentioned they are in Iran. I'm sure sanctions make many things difficult to come by.

author: Gyro
author_rank: Super Contributor
timestamp: December 08, 2022, 09:15:00 pm
content: Quote from: tatel on December 08, 2022, 03:20:48 pmNo, you're right. Having an FPGA and intelligence in the unit itself means that the 1022 can do proper multi-mode hardware triggering and only send the needed display data over USB (it's this low bandwidth requirement that allows it to include USB isolation at such a low cost too). The 6022BE is nothing more than a glorified streamer (just like the $10 logic analysers), it has to throweverythingat the PC in real time so that (edge only) triggering can be done in s/w there. This demands a lot from the High speed USB latency and PC performance, and still only achieves a very optimistic 48Msps (versus a solid 100Msps for the Owon).The VDS1022 matches it's price point well, that's why it has been around for such a long time (just like the Rigol DS1054Z has in its own niche). Owon make higher bandwidth and 4 channel USB scopes too but they bang head-on into the price of lower end bench scopes. They only make sense for very portable uses, there the user is already carrying a laptop - even this is starting to be erroded but the better handheld scopes.

author: BillyO
author_rank: Super Contributor
timestamp: December 08, 2022, 11:42:38 pm
content: Quote from: tatel on December 08, 2022, 03:20:48 pmMy real hands on experience with USB scope covers the absolute worst ($50 Instrustar ISDS205 which only meets it's spec halfway .. never, ever buy this unless you can get it for $5 just to see how bad a scope can be) to the low to mid-range (Hantek 6074BC which exceeds it's spec, especially if using only one or two channels). These both seem to work just as well when plugged into USB2 or USB3. I think they do some data reduction in hardware and pass preprocessed information on to the PC such that teh USB speed is not a significant issue. While I have briefly used "high end" Picos in the past, I have never seen one that needed anything beyond USB2. Even the 9300 series @ 25GHz only requires USB2.These days I'm like you. I too use benchtop scopes almost entirely. The Hantek 6074BC I have in my desk in my office .. just in case.

author: tatel
author_rank: Frequent Contributor
timestamp: December 09, 2022, 12:10:29 am
content: Quote from: mwb1100 on December 08, 2022, 05:08:24 pmI too guessed that at the first moment, but I don't know if China is sanctioning Iran. It would surprise me, Iran is getting into Shanghai Cooperation Organization after all. If China is not sanctioning Iran, then I guess the price difference, between what AliExpress shows in my screen and the prices OP seems to be getting, would be taxes?

author: sx57
author_rank: Contributor
timestamp: December 09, 2022, 10:32:16 am
content: @tatel AND mwb1100I think it is not the taxes but the importers. they sell with as much profit as they want. then the retailers are the same. none of them will take responsibility of a possible faulty product easily after selling the product most of the time unless you buy from internet website which has somewhat better support. iran is a sh*t and corrupt country. everyone can break the law easily with money. so you need to buy very cautiously. manytimes, you may buy a product for tmore than two times the price on aliexpress or any other reference. you can find good deals too, specially on things like phone chargers and cables when there is a lot more competition but in the realm of oscilloscopes, it is a complete joke and mess with very few options available .i wish i could measure the noise with mysound card, it would have24 bit resolution,way higher than most of the oscilloscopes. i know i should be able to measure the main's ripple and it's harmonics(50hz and up) but the damn SMPS noise is gonna be at different high frequency bands. finding an oscilloscope is a must if i want to it right.

author: sx57
author_rank: Contributor
timestamp: December 09, 2022, 10:51:24 am
content: Quoteat BillyOthen i guess i envy youi wish i could have such nice scopes. man when i used the sound card as an audio amplifier measuring device, seeing and analyzing that waves was so cool. now think of real devices you can have on your bench

author: tatel
author_rank: Frequent Contributor
timestamp: December 09, 2022, 11:04:01 am
content: Quote from: sx57 on December 09, 2022, 10:32:16 amCan't you buy from AliExpress?

author: sx57
author_rank: Contributor
timestamp: December 09, 2022, 11:18:51 am
content: Quote from: tatel on December 09, 2022, 11:04:01 amno. not only we have no international credit cards in iran because of the sanctions, but also the shipping cost is gonna make it about the same price in iran.

author: tatel
author_rank: Frequent Contributor
timestamp: December 09, 2022, 12:09:58 pm
content: Of course, the credit card. Boy, how they got us by the balls. Well, I hope this will happen soonhttps://www.russia-briefing.com/news/iran-set-to-join-russia-s-mir-card-payment-system.html/https://eng.allexprs.info/oplata-zakazov-aliekspress/article/magazin-aliexpress-gotov-prinimat-k-oplate-bankovskie-karty-sistemy-mir-rossii.htmlEDIT: perhaps you know an international truck driver or a sailor?

author: sx57
author_rank: Contributor
timestamp: December 09, 2022, 12:45:43 pm
content: thanks for the news. i hope too.no i don't know anyone unfortunately.

author: JacobPilsen
author_rank: Regular Contributor
timestamp: December 09, 2022, 05:56:57 pm
content: Is it allowed to buy it, for example, in Turkey and then transport it across the border?

author: BillyO
author_rank: Super Contributor
timestamp: December 09, 2022, 07:00:45 pm
content: Quote from: sx57 on December 09, 2022, 10:51:24 amTo be honest they have been acquired over a looooong time. My first scope was a 5MHz single trace Heathkit I built back in 1976. It cost me $180 and that was an absolute fortune for me back then. I eventually gave it away to a young student of electronics but I wish I had kept it. You can check it out in the 1976 catalog on page 66. In fact, check out the whole catalog. The world of hobby electronics lost a lot when Heathkit closed their doors.https://worldradiohistory.com/Archive-Catalogs/Heathkit-Catalogs/Heathkit-Spring-1976.pdf

author: sx57
author_rank: Contributor
timestamp: December 09, 2022, 10:18:43 pm
content: @JacobPilseni think yes it is allowed to buy one.@BillyOthanks for the info.

author: james_s
author_rank: Super Contributor
timestamp: December 09, 2022, 10:27:59 pm
content: Quote from: BillyO on December 09, 2022, 07:00:45 pmHobby electronics was on life support leading up to Heathkit closing their doors. They couldn't compete with regular mass produced equipment. Modern automated manufacturing meant that there was no savings in selling kits for things you could buy already built and ready to use. It wasn't until the Arduino came along that hobby electronics was reborn, for a while I was afraid the entire hobby was going to go extinct.

author: BillyO
author_rank: Super Contributor
timestamp: December 09, 2022, 11:30:51 pm
content: Quote from: james_s on December 09, 2022, 10:27:59 pmYes, it was and that's something I personally never quite figured out. I bought and built a lot of Heathkit stuff, but it was never because it was cheaper. It was mostly that I could build it myself, see and understand the design and have a load of enjoyment in the process and in a lot of cases, their stuff was just unique in many ways. When I bought that scope kit there were cheaper pre-made alternatives and cheaper used alternatives. But where's the fun in any of that?

author: Watth
author_rank: Frequent Contributor
timestamp: January 24, 2023, 07:56:23 pm
content: Quote from: xmris on December 05, 2022, 06:47:21 pmThe "Homemade SMD to DIP adapter" one? Brutal!

author: rstofer
author_rank: Super Contributor
timestamp: January 24, 2023, 11:33:37 pm
content: Eevblog video 1022 for $50 scope. May not apply in Iran