Oscilloscopes - Use Cases - Page 1
Forum section: electronics / beginners

author: Unknown
author_rank: Unknown
timestamp: April 21, 2020, 06:33:09 pm
content: After a 30 year lapse, I am getting back into electronics... but this time as a hobby.In the 80's, I was a service tech for Xerox's datacenter printers. That printer had a CDC Tape Drive on it as well as a CDC Hard Drive and a DEC PDP 11/34 computer. I frequently used a scope to troubleshoot those components as well as other parts of the system. For the most part, we used either one or two probes to do what was needed.Today, I want to be able to troubleshoot and repair board/components that break on my motorhome and learn as much as I can about electronics. In the short time that I have been back, I have added Arduino and ESP32 to my interests.I would love to tell you where the hobby will lead me but I really have no idea. I know I love to learn and I can spend a bit of money on the hobby.There are a ton of posts and videos about Oscilloscopes and I have watched and read many of them but I have yet to find one that talks about why I might want 300 HMZ vs 50 Mhz or 4 probes vs 2 probes.I know that with 4 probes, I can look at SPI data and that sounds super interesting.Can you all give me some real-world examples of when you might use 4 probes and/or when you would need 300 or 200 MHZ?BTW: My wife and I live full time in the motorhome so storage is tight. I currently have a Brymen BM869s meter, DER EE DE-5000 LCR meter and a Siglent SPD3303X-E power supply. I think an oscilloscope is next and a function generator will be after that... but that REALLY needs to be it..... The wife said so.BTW2: At the moment, I am leaning towards a Siglent SDS1104X-E 100MHz Four-channel oscilloscope but want to be sure that I don't "really" need something more.JohnnyG

author: tggzzz
author_rank: Super Contributor
timestamp: April 21, 2020, 08:12:00 pm
content: An oscilloscope shows you the shape of analogue waveforms, and almost all waveforms are analogue.In a digital system those analogue waveforms are interpreted by the receiver as digital signals, but in order to be able to do that correctly the analogue waveforms have to meet specific criteria in terms of voltages and times, especially setup and hold times.A good strategy is to use an oscilloscope to verify that the analogue waveforms will be correctly interpreted. Once that signal verification has been completed, flip to using digital domain equipment to observe digital signals, especially logic analysers and printf statements.Logic analysers can be very simple and cheap, and can observe many digital signal simultaneously; 8 to 64 are common. LAs can also have far more complex triggering and filtering capabilities, which enables you to rapidly ignore the irrelevant stuff that a scope must capture.So, use a scope for signal verification. The key parameter is the waveform's rise time, which equates directly to bandwidth (BW = 0.35 / rise time). Modern digital waveforms have rise times of a couple of ns and shorter.The other factor is the probes. Scope probes are relatively expensive, logic analyser connections are much cheaper.

author: Unknown
author_rank: Unknown
timestamp: April 21, 2020, 08:54:17 pm
content: Quote from: tggzzz on April 21, 2020, 08:12:00 pmAre you suggesting that I might be better off with a faster scope with fewer probes and then use a logic analyzer for the spi stuff?-G

author: tggzzz
author_rank: Super Contributor
timestamp: April 21, 2020, 09:27:10 pm
content: Quote from: JohnnyG56 on April 21, 2020, 08:54:17 pmThat might be a consequence, but only you know your use cases and other constraints such as cost, space and other things you might want to spend your money on.The key point is to sit down and think how you could do something if tool X was not available. Plus what you couldn't do without X. Often there is a lot of overlap between tools.With understanding, care and imagination, you can do more with less. See my .sigOne approach, which has disadvantages as well as advantages, is to only buy X once you have run into a problem that only X can solve.If space is at a premium, consider what you could do with an Analog Discovery. It contains a 30MHz scope, a function generator, a limited pattern generator and limited logic analyser. You have to be sure that your DUT won't exceed the input voltage ratings.

author: Old Printer
author_rank: Frequent Contributor
timestamp: April 22, 2020, 12:27:47 am
content: While I was agonizing over the scope choice (noob) I bought an Analog Discovery because it supplied so many tool besides the scope, and I could cover a lot of bases. I eventually bought the SDS1104X-E but have always been glad I have the AD as well. It is a learning tool so not as powerful as a dedicated scope or LA, but plenty to learn on and it still has a place on my bench. Do a search, there has been a lot written here on both.

author: Electro Detective
author_rank: Super Contributor
timestamp: April 22, 2020, 01:01:21 am
content: Quote from: JohnnyG56 on April 21, 2020, 06:33:09 pmMy 'something more' suggestion would be to consider a non-shared controls oscilloscope for less troubleshoot and comparison thinkingi.e. 4 channels with 4 lots of controls and of course 4 probesIf 200 mhz isn't much dearer, I'd consider thatand don't forget a differential probe or two if sussing out problems in the motorhome, to avoid any earth/ground mix up BANGS! = candles, cold food,and bent ears

author: james_s
author_rank: Super Contributor
timestamp: April 22, 2020, 02:03:28 am
content: Ask this question and you'll get as many different answers as there are people responding.Sounds like space is (or should be) your highest priority so that rules out analog scopes and older DSOs.You can spend as little as about $300 up to tens of thousands depending on what you need and what your budget allows. Despite what some might argue, a 100MHz scope is adequate for nearly any hobbyist use, if you really needed more than that you'd know. Also this doesn't have to be a major life decision, the popular Rigol, Siglent and similar scopes offer a lot of bang for the buck and hold their value well, if you later decide to upgrade you should be able to get a substantial part of your investment back provided you've taken good care of the thing and kept it in nice shape. Personally I'm somewhat inclined toward the Rigol DS1054z, it's easily hacked to 100MHz, gives 4 channels and for around $350 it even comes with a full set of four probes. It's a nice compact little instrument that is very popular so there's a lot of tips and information out there. Prices rise sharply above 100MHz and VERY sharply above around 250MHz. No matter how much bandwidth you have there will be times when it would really be nice to have more but that's the case with many things in life.

author: rstofer
author_rank: Super Contributor
timestamp: April 22, 2020, 05:57:31 am
content: I bought the Rigoll DS1054Z a couple of years ago when the SDS1104 did't exist. Today, I would probably buy the Siglent and unlock it for 200 MHz bandwidth (details elsewhere) and 4 channels.When I bought the Rigol, bandwidth was covered by a Tek 485 350 MHz scope (which I still have) and I really wanted 4 channels for SPI. Plus the advanced features of a DSO. There really is no comparison between an old analog scope and a modern DSO.From the Fourier series, we know that displaying a square wave takes a lot more bandwidth than the fundamental frequency. In fact, we probably want to pass up through at least the 9th harmonic so a 100 MHz scope can do a decent job on 10 MHz square waves. That's ok, very seldom do signals outside of a chip run at multiple hundreds of MHz. Maybe DDR memory or something like that but that is way out of my league. 100 MHz is enough, I would still unlock the Siglent to get 200 MHz.You want a use case? Here's one! I am doing some hardware experiments on a Raspberry Pi 4. These are all low frequency kinds of things because the Pi just doesn't support really high speed stuff on the GPIO pins under Linux. These experiments are created using the Pi's geany IDE so I can edit, compile and execute from a single program. I run the Digilent Waveforms software on the same Pi to view the output by way of an Analog Discovery 2. All on the same Pi - code, compile, run, debug all on the same device. But wait! There's more...Using VNC, I can get at my Pi's desktop and run the entire show from my iPad in the media room while watching NCIS LA (as I was a few minutes ago). Now that's a 'use case' and you'll note there was no single purpose oscilloscope anywhere to be seen.There are 4 example problems beginning at message 52 here:https://www.eevblog.com/forum/testgear/starter-scope/50/Let me know when you find a scope that can do any of these things! Sure, bandwidth is down around 30 MHz but when it comes to electronics experimentation, there is no equal.I'm going to pile on with the others above who suggested a 100 MHz scope will carry you a long way. When you need a 1 GHz scope, you'll know it and will simply sell off the 100 MHz scope to make a down payment on whatever comes next. Worst case, the DSO will fetch 1/2 of the initial cost - maybe more.I would certainly go for 4 channels just because there are a lot of DSOs that have them. Nevertheless, we used 2 channel scopes since the Wooly Mammoths roamed the Earth so I guess I can't make a real statement about the necessity of 4 channels. I would still go out of my way to buy them but I'm pretty sure we made it to the Moon with 2 channel scopes!I can't think of anything in a motorhome that is user repairable and would require a scope. I certainly don't think an AD2 would be appropriate. Then again, I haven't spent a lot of time in a motor home.

author: Unknown
author_rank: Unknown
timestamp: April 22, 2020, 01:38:33 pm
content: Quote from: tggzzz on April 21, 2020, 09:27:10 pmWell, that right there is the problem. As a new hobbyist, I really don't know what I might use it for. I figured that I would ask the inverse.If I had a 300 MHZ scope, what could I use it for or if I had a 600 MHZ scope, what could I use it for? I might look at the things that a 600 MHZ scope is used for and think... I can see me getting into that.... I need to go and rob a bank. (JK, I would just ask Santa.)JohnnyG

author: Unknown
author_rank: Unknown
timestamp: April 22, 2020, 01:55:59 pm
content: Quote from: rstofer on April 22, 2020, 05:57:31 amThank you for your reply, it was very informative. I would unlock the Siglent for sure.I was done after the scope, now I want an Analog Discovery too. Thanks.... My wife does not like you LOL.Motorhomes are amazingly complicated. Here is a real-life example of where I think that a scope (and possible the Analog Discovery) could be used. The leveling system uses SPI to talk between the control board and the user panel. I have a light out on the user panel. To replace the user panel is $250 and the control board about $500. It might be a faulty light or it might be the control board is not turning on the light. I would like to know before I try to repair the board. There are many such systems in my MH.JohnnyG

author: Old Printer
author_rank: Frequent Contributor
timestamp: April 22, 2020, 04:03:18 pm
content: One additional Analog Discovery advantage is that it comes in a very small, inexpensive looking package, particularly as compared to a bench scope. Very few wives will know off the cuff what it costs. I would be lying if I said this did not enter into my purchase decision. Second scope is always an easier sell, besides, the little AD is cute, my wife's exact words

author: jc101
author_rank: Frequent Contributor
timestamp: April 22, 2020, 04:36:42 pm
content: I'd also not rule out a decent USB scope, something like a Picoscope 3000 which can have 4 analogue and multiple digital channels too. Has the advantage of not needing to run a mains inverter to use it, which may handy in a motorhome at some point.I'll admit they are not for everyone, but can be very handy when space is a premium. I have a traditional bench scope, but have found a USB one is also handy when helping out in a field or remote hanger somewhere.

author: wizard69
author_rank: Super Contributor
timestamp: April 22, 2020, 07:25:32 pm
content: Your question is harder to answer than you might realize. The fact that you are extremely space constrained has me strongly leaning towards this suggestion: USB based hardware. I'm assuming here that you have a decent laptop (or even a desktop) to work with the USB based devices. Now there is a huge array of possible hardware available, so we still get back to what sort of spec the scope should support.Here it really comes down to what you intend to do. If I was to buy a real o'scope these days I wouldn't even consider a scope of less that 100MHz band width and probably much higher. That however is a stand alone device and would be purchased or the long term. Some of the USB options are rather cheap and might not be considered long term buys so you have lots of options.

author: Old Printer
author_rank: Frequent Contributor
timestamp: April 22, 2020, 08:36:29 pm
content: Keep in mind, one wrong slip at the wrong voltage and a USB scope will eat your laptop.

author: Gyro
author_rank: Super Contributor
timestamp: April 22, 2020, 08:43:49 pm
content: Quote from: Old Printer on April 22, 2020, 08:36:29 pmAlthough a galvanically isolated one would mitigate the risk.

author: tggzzz
author_rank: Super Contributor
timestamp: April 22, 2020, 08:55:03 pm
content: Quote from: Gyro on April 22, 2020, 08:43:49 pmIsolated HV probes are probably cheaper, and could be used on other scopes.

author: daqq
author_rank: Super Contributor
timestamp: April 22, 2020, 09:06:31 pm
content: QuoteIf space is a really important issue, then there are scopes that have a function gen integrated, as well as other instruments. Take a look at the Tektronix MDO 3000 (or more modern) series. Includes unlockable arbitrary waveform generator, logic analyzer and spectrum analyzer, all within one instrument.Mind you, it does cost a pretty penny. There are some cheaper scopes that have a subset of those functionalities, such as some of the offerings from R&S. And I'm sure many more.

author: Gyro
author_rank: Super Contributor
timestamp: April 22, 2020, 09:10:44 pm
content: Quote from: tggzzz on April 22, 2020, 08:55:03 pmTrue.

author: RoGeorge
author_rank: Super Contributor
timestamp: April 22, 2020, 09:17:14 pm
content: It looks like an Analog Discovery will be the ideal tool for you, simply because it will occupy virtually no space at all, it will consume virtually no power at all, virtually no weight, it's many instruments in one, and it will cover all the areas of interest you enumerated in the begining.On top of that, it will be an excellent learning tool, and capable of many interesting experiments that can keep you busy for years. Can be an oscilloscope, a generator, a logic analyzer, a data logger or a box for automation in your motorhome, and so on, the possibilities are endless.

author: Unknown
author_rank: Unknown
timestamp: April 23, 2020, 02:12:36 am
content: Quote from: RoGeorge on April 22, 2020, 09:17:14 pmThanks All!My comment about space has more to do with not being able to have multiple scopes like I soo on some benches (in videos). I also would not want to buy an old analog scope for the same reason. The motorhome is a 45 feet long Newmar Mountainaire, storage is not really that big of a problem. I do projects on my kitchen table. I could easily stack the power supply, a scope, a function generator, and have plenty of room for the meter, soldering station, other tools, and whatever I am working on.That being said, I will take a serious look at the Analog Discovery, it shoulds like an interesting device. But it looks like it costs $279, to me, there is no difference between $279 and $500. Maybe I'll end up with both... :-)JohnnyG

author: tautech
author_rank: Super Contributor
timestamp: April 23, 2020, 02:26:52 am
content: As for getting both, another option as you have indicated a FG will be of use is to get the $159 SAG1021I AWG option for the SDS1104X-E. These are now insulated output so less chance of a WTF moment.https://siglentna.com/product/external-arbitrary-waveform-generator-2/

author: jackthomson43
author_rank: Contributor
timestamp: April 23, 2020, 02:38:23 am
content: You can also try Oscilloscope inProteussoftware.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 23, 2020, 09:28:38 am
content: Whole generations have grown up with 20MHz analog scopes. Compared to those almost any modern scope is Gianormous in capabilities. More bandwidth is nice to have, But I almost always put the brakes on with the 20MHz built in filter, to keep the noise down.If you have any doubt about needing or wanting an Logic analyser, then the first thing you shoud do is go to your favourite Chinese outlet and buy one of those small USD10 boxes.They have a Cypress CY7C68013A in them and are extremely useful for working with microcontroller stuff such as I2C, SPI, UART and a multitude of other serial data formats.They work with the Open Source Sigrok software.This thing used to be sold for around USD200 on the west side of this globe.Sigrok has built in decoders for 100+ different protocols, and if you have a protocol that is not in Sigrok (yet), well, a decoder is a plugin for Sigrok and about 2 to 4 pages of Python, and you have 100+ examples to write your own.The USD10 really makes it a no-brainer. Just start with it, and then if you know more about what you can do with it or what you needs are, you can always upgrade to more capable hardware. Heck USD10 is lunch money.

author: tggzzz
author_rank: Super Contributor
timestamp: April 23, 2020, 10:32:35 am
content: Quote from: JohnnyG56 on April 23, 2020, 02:12:36 amYou can download the Analog Discovery GUI and play with it to see what it can do. It isverysmall, and has other instruments, but beware the cost of buying the BNC adaptor and probes. Provided you don't need electrical isolation and there are no "high voltages", you could use any very cheap probe that has the appropriate compensation range. Beware of *1/*10 switchable probes: sooner or later youwillhave it in the wrong position.If, later on, you decide you need more, youmightbe able to flog it on fleabay. e.g. transients due to motor startups.

author: Unknown
author_rank: Unknown
timestamp: April 23, 2020, 12:37:42 pm
content: Quote from: Doctorandus_P on April 23, 2020, 09:28:38 amI watched the Analog Discovery 2 QuickStart videos and that is an amazing piece of software with tons of capabilities. Amazon has the "pro" kit for $349. For whatever reason, I can't wrap my head around spending that kind of money on a device of that size when I can buy a "real" scope for not much more. As the Doctor said, I can add "toys" for playing/learning for not a lot of money. At $150, it would be a no brainer, I would get the Analog Discovery just to play with it but at $350, give me the "real thing".The SAG1021I AWG option looks interesting as well. If I got a Siglent SDS1104X-E and added these options:16 digital channels(Option), an external powered 25 MHz AWG module(Option), a USB WIFI adapter(Option) What would be missing between this setup and the AD2? I wish there was a video on the SAG1021I AWG, I would love to learn more about it.BTW: Thanks for the help, Y'all are awesome!BTW2: I sell software for a living so I know that there is a lot of R&D that went into the AD2 which might justify some of the price, but a scope has a lot of "software R&R" too.JohnnyG

author: Old Printer
author_rank: Frequent Contributor
timestamp: April 23, 2020, 02:01:38 pm
content: The original Analog Discovery was sold to students for $99 for years. With patience, they can be had on eBay in the $125 range. After getting my AD2 I managed to grab an AD1 for $50, an exception no doubt, but deals do come along if you are vigilant. The AD1 is virtually the same as the AD2 except for the variable power supply, a small addition that could be inexpensively worked around.

author: rstofer
author_rank: Super Contributor
timestamp: April 23, 2020, 02:24:10 pm
content: Quote from: JohnnyG56 on April 23, 2020, 12:37:42 pmThe Pro kit is just $300 at Digilent plus there is a CV-19 discount of 20% on the Ultimate Bundle - but it's still pricey.Yes, the AD2 is pricey and appeals only to students and a very small group of hobbyists. I have a bench full of traditional stuff but for some reason, I find myself using the AD2. A 17" laptop or 27" desktop screen is pretty compelling. A screen shot and a little cropping with Paint and the output is publishable. Of course, this can also be done with traditional tools in one way or another. Hm... I have never tried to download the setup of my AWG as a graphic. If you are going to display results, you should probably display the setup.In terms of an AWG, I bought an 80 MHz Siglent SDG2082 a while back and it's a pretty nice tool. The ability to combine several harmonics of the fundamental with adjustable magnitude and phase is pretty sophisticated. I'm not sure that 80 MHz is a requirement, one of the lesser versions might be entirely adequate. Pay attention when somebody says 80 MHz! That's for the sine wave only, any other waveform is limited to 25 MHz. Regardless of the AWG, read the specifications.Our local university uses the AD2 for their lab classes. It's a lot cheaper for the university to provide an AD2 per workstation than a complete bench full of equipment, regardless of team size.I have been looking at the Diglent Analog Discovery Studio ($600)https://store.digilentinc.com/analog-discovery-studio-a-portable-circuits-laboratory-for-every-student/Among other things, it has more in the way of power supplies plus the breadboard is integrated and interchangeable.

author: rstofer
author_rank: Super Contributor
timestamp: April 23, 2020, 05:49:07 pm
content: When the AD2 is using flyleads and not the BNC adapter, both scope channels have differential inputs. In Reply 55 to this thread, I plot the phase shift in an RC circuit:https://www.eevblog.com/forum/testgear/starter-scope/50/In order to measure the voltage across the resistor, both leads of channel 1 are away from ground. The + lead is on the input and the - lead is on the junction between the resistor and capacitor. This measurement is NOT ground referenced.Yes, this can be done using two channels on a conventional scope using the Math function A-B (or whatever it is called on some specific scope) but it just comes along for free on the AD2.This differential input functionality of the AD2 is lost when the BNC adapter is used because both connectors are grounded and that means that one side of each channel is grounded through the connector. I find flyleads more useful for breadboarding anyway. I'm not working on anything at high frequencies.

author: tautech
author_rank: Super Contributor
timestamp: April 23, 2020, 08:28:51 pm
content: Quote from: JohnnyG56 on April 23, 2020, 12:37:42 pmIt is, previously our only insulated output AWG was the now obsoleted SDG5000 range.Standalone AWG's are always higher amplitude and mostly 2 channel but of course your space restraints could make the SAG option more attractive despite its limited output capability being relatively feeble from a power electronics POV is no better or worse than any other USB powered equipment.You can find the detailed specs in the SDS1104X-E datasheet and usage guidance in the scopes User manual.QuoteThis is on the previous non isolated output model:https://siglentna.com/video/adding-a-function-generator-sag1021-to-an-sds1004-sds2000x-e-series-oscilloscope/QuoteThe AD2 will be cheaper but there are less concerns with voltage ratings with the scope. A moments inattention and you can quickly exceed the AD2's input ratings. Hey but like all gear you need use it with knowledge and care.

author: james_s
author_rank: Super Contributor
timestamp: April 23, 2020, 08:31:44 pm
content: Quote from: Old Printer on April 23, 2020, 02:01:38 pmOdd that the AD2 is so much more expensive. I'm surprised they didn't keep offering the AD1 alongside it, the power supply doesn't really sound very useful given good power supplies are not all that expensive anyway.

author: rstofer
author_rank: Super Contributor
timestamp: April 23, 2020, 09:45:36 pm
content: Quote from: james_s on April 23, 2020, 08:31:44 pmI don't think Digilent thinks much of the hobbyist market. Many of their products are aimed straight at education with no pretense of being economical. Given that education is never free, students just hit up Mom and Dad for the money. For a serious student, the cost of these gadgets, after the student discount, isn't so unreasonable.Given that Digilent is owned by National Instruments, I suspect their focus will remain on education.http://dangerousprototypes.com/blog/2013/01/24/national-instruments-acquires-digilent-inc/

author: Old Printer
author_rank: Frequent Contributor
timestamp: April 24, 2020, 01:07:31 am
content: I recall when Digilent ended the $99 student price, at the time they said it was originally underwritten by National and Xilinx but was being discontinued, as in nothing good lasts forever. They still offer a student discount, just not nearly as cheap. They redesigned the case and added the variable power supply and jacked up the price. Under the hood the AD2 is virtually identical, though they did change the way some of the specs are interperted to give it the appearance of higher performance. Of course the software is always being upgraded. I don’t recall the finite details but I did a lot of homework before I bought mine 3+ years ago. If you can find a deal on an AD1 grab it, it will serve you just as well as the new shinny one except for the variable PS. That said, I love my SDS 1104X-E too.

author: Electro Fan
author_rank: Super Contributor
timestamp: April 24, 2020, 05:16:55 am
content: Quote from: JohnnyG56 on April 21, 2020, 06:33:09 pmLots of good advice from people here.Ultimately it comes down to your sense of your needs (which are understandably hard to fully forecast) - but based on the equipment you have already selected you have demonstrated good decision making on your selections. Just another opinion but I think you can safely go with the Siglent 1104X-E. It might or might not be your last scope but it’s likely to get you well down the path and by then you will know better what else you might need. The 1104X-E’s bandwidth, four channels, serial decoding and lots of other features will keep you busy. As for a logic analyzer, you might be good with just the scope but you can get started with an eBay LA for less than $20 plus free Sigrok PulseView software. Again, might or might not be your last LA but after using the 1104X-E and an entry LA you will know much more about if or what else you might need. Main thing left is probably the function generator so leave room (budgetary and physical space) for that plus a couple DMMs if you don’t already have those (plus parts, wire, cables, adapters, hand tools, etc). My guess is you would enjoy the 1104X-E a lot.

author: rstofer
author_rank: Super Contributor
timestamp: April 24, 2020, 07:04:08 pm
content: Quote from: james_s on April 23, 2020, 08:31:44 pmBut carrying a PS in your backpack gets old, quick! Not to mention the AWG and Logic Analyzer. Gonna need a bigger backpack!The AD2 is aimed at students and they live out of their backpack. A laptop and an AD2 will carry a student to graduation (probably) and is a lot more capable than what I had back in college.Today, I was looking at a simple project using the Raspberry PI I2C bus to read an I2C based ADC. Not a big project and it worked right out of the box but I thought I should look at the decoding. OK, fine, decoding works, as expected, and it is a whole lot better than decoding only the visible scope trace. Then I took another look under the Custom tab and I see where I can script an entire conversation using some dialect of C. In fact, there are Examples to get me started.I don't know of any scope that willwriteI2C and I'm not sure how many LAs can be scripted and, while I try to avoid I2C at every opportunity, that may change. Not only can I see the signals with the scope leads, I can watch transactions with the Protocol component of the AD2 and the DIO leads. Plus, I can script an entire transaction. Pretty neat!Yes. it's pricey but the student won't need a hand truck to carry around a lab full of equipment. Yes, I know, schools have fixed labs - but not during the lockdown and it's not nearly as convenient as working at your leisure if only to supplement the lab class.If I keep playing with this thing, I'm going to become an evangelist.

author: james_s
author_rank: Super Contributor
timestamp: April 24, 2020, 08:22:49 pm
content: No reason it has to be a big heavy thing. A compact variable power supply of similar capabilities could be tiny and cost very little. It's not like the AD2 can supply 20+V at several amps on multiple channels.

author: JeanF
author_rank: Regular Contributor
timestamp: April 24, 2020, 08:35:28 pm
content: Quote from: rstofer on April 24, 2020, 07:04:08 pmhaha, I think you already areI tried to google "analog discovery site:eevblog.com/forum/" and count your posts about it, but I quickly gave upand instead I bought an AD2 a few days ago, partly thanks to your commentsI got it for 150€, new in box, secondhand from a guy in the local equivalent of craigslist, I think it's a pretty good deal. I'm eager to try it!

author: rstofer
author_rank: Super Contributor
timestamp: April 24, 2020, 09:13:39 pm
content: Quote from: JeanF on April 24, 2020, 08:35:28 pmI hope you enjoy it. Right off the bat, I would connect the AWG to the Scope and see how it all works out.I really should back off on the AD2, it's not like I don't have a fairly complete lab but the thing is, I actually USE the AD2 and most of the other stuff sits waiting for more complex projects.Part of the reason I like the AD2 for breadboarding is the ease of using the flyleads. I have a bunch of header pins cut to various widths that I can put in the breadboard and then just connect a lead. This is a lot more functional than 4 scope probes hanging off component legs.Enjoy!

author: Unknown
author_rank: Unknown
timestamp: April 25, 2020, 12:01:41 am
content: I couldn't take it anymore!!! I order the ultimate bundle. Their website says that then engineer deal expired on 4/17. I emailed them to ask if they extended it... they replied back with a 20% off coupon code.With all of the glowing reports, I don't know how I can go wrong by purchasing it.I will see where this takes me and if I need a real scope in the future, I'll get one.Thank you all so much!!!John

author: tggzzz
author_rank: Super Contributor
timestamp: April 25, 2020, 12:15:23 am
content: With skill and imagination you can do a lot without a scope - and even more with one.Have fun learning how to use your new tool to full advantage.If you haven't already, make sure you understandwhyyou can blow up a scope if you put the probe shield in an "unfortunate" place...

author: Old Printer
author_rank: Frequent Contributor
timestamp: April 25, 2020, 02:59:55 am
content: Good to hear that John, I am quite sure your will get a lot of use from your AD. Look up a guy on YouTube Tomtektest. He has done a lot with the AD. I am 67 and the eyes are not so good anymore. With the AD hooked to a pair of 25 inch monitors I can have a lot going on at once and see it all in detail. Not sure I could hack living full time in a motor home, but with current events as they are, it does have a certain appeal. Safe travels.

author: rstofer
author_rank: Super Contributor
timestamp: April 25, 2020, 03:37:21 pm
content: As discussed, the AD2 is an expensive piece of equipment. To that end, it would be wise to read all of the specifications over at Digilent and pay particular attention to the voltage limits. The limits are a little different when using the BNC adapter. I might consider using 10x probes with the adapter. In fact, I bought a pair of FIXED 10x probes from Probe Master with the aim of preventing an errant 1X selection when 10X is required.Most of the stuff I do is at +-15V or just +12V (or less) and I prefer using the built-in adjustable +-5V supplies as I know they can't go overvoltage. Don't forget to get the wall wart if you want higher currents from the AD2. Just about everything I do with the AD2 uses the internal supplies - there is not even a possibility of overvolting the tool.For an easy entry, grab up a 10k resistor and a 0.1 ufd ceramic capacitor and duplicate the experiments I posted over here (starting at reply 52)https://www.eevblog.com/forum/testgear/starter-scope/50/I spent a lot of time with just those two components. In effect, a review of the early college classes where we had no capability for permanently displaying the results and the math was done with a slide rule.If you aren't absolutely sure what voltage you are going to probe, use a DMM first. And stay clear away from mains! Dave's video shows how really bad things can happen and, with a USB scope, you can fry the PC right along with the AD2. A powered hub might make sense.These PowerBricks might make sense:https://store.digilentinc.com/powerbricks-breadboardable-dual-output-usb-power-supplies/The _+-12V brick might work just fine for dual rail op amp projects. Note that each brick provides both a + and - output. Of course I have the full set!

author: rstofer
author_rank: Super Contributor
timestamp: April 25, 2020, 03:46:34 pm
content: While I'm on a tear, don't forget Alt-PrtScrn and Paint. Save your output files as JPGs to save a little size. Even then, they won't always be small enough to save at EEVblog. I have downscaled the resolution on some images but I have forgotten how I did it. I think the limit is 1MB.The point is, post your results!

author: tautech
author_rank: Super Contributor
timestamp: April 25, 2020, 07:56:40 pm
content: Quote from: rstofer on April 25, 2020, 03:46:34 pm5 MB now but there's no need to post such large screenshots when 100KB is plenty and Paint has provision for the better .png files that are smaller still.

author: rstofer
author_rank: Super Contributor
timestamp: April 25, 2020, 10:18:40 pm
content: Quote from: tautech on April 25, 2020, 07:56:40 pmI prefer the .png format but, and I'm probably mistaken, it doesn't seem like they will open in the browser. They will download just fine and I can open them in Paint but in my brief tests (always dubious), I couldn't display them in the browser along with the text.Probably something I'm doing wrong...

author: tautech
author_rank: Super Contributor
timestamp: April 25, 2020, 11:13:08 pm
content: Quote from: rstofer on April 25, 2020, 10:18:40 pmFor images to show you need post the URL of your uploaded image file within the image flags. [ img ] URL [/ img ]

author: james_s
author_rank: Super Contributor
timestamp: April 26, 2020, 12:44:31 am
content: I've been using Irfanview for this sort of thing for about the last 15 years. It's far more capable than Paint for cropping, adjusting and viewing photos.

author: SilverSolder
author_rank: Super Contributor
timestamp: April 26, 2020, 12:53:40 am
content: Quote from: rstofer on April 25, 2020, 10:18:40 pm.png is supported by all browsers nowadays.

author: PixieDust
author_rank: Frequent Contributor
timestamp: April 27, 2020, 05:45:46 am
content: As a rule of thumb, digital signals require x5 bandwidth of the digital signal's frequency to paint a realistic picture of your scenario. So if you foresee playing with up 60Mhz clocks, you will need a 300Mhz scope.

author: tggzzz
author_rank: Super Contributor
timestamp: April 27, 2020, 07:06:55 am
content: Quote from: PixieDust on April 27, 2020, 05:45:46 amFalse, pure and simple. Theonlykey parameter is the rise/falltime.For a quick overview of the theory, plus some practical measurements, seehttps://entertaininghacks.wordpress.com/2018/05/08/digital-signal-integrity-and-bandwidth-signals-risetime-is-important-period-is-irrelevant/

author: SilverSolder
author_rank: Super Contributor
timestamp: April 27, 2020, 01:41:00 pm
content: Quote from: tggzzz on April 27, 2020, 07:06:55 amAre you saying that the bandwidth needed is the same whether there is a single pulse on your screen, or a train of them arriving at 60MHz?

author: tggzzz
author_rank: Super Contributor
timestamp: April 27, 2020, 02:17:39 pm
content: Quote from: SilverSolder on April 27, 2020, 01:41:00 pmCorrect.If you want an anthropomorphic hand waving explanation, realise that when the circuit "sees" the first edge, it neither "knows" nor "cares" when the next edge will occur. It just responds to the edge.If you want a more formal explanation, I refer you to Fourier Transform theory.If you want to see the practical effects that confirm the theory, see the page I referenced.

author: james_s
author_rank: Super Contributor
timestamp: April 27, 2020, 04:01:42 pm
content: Quote from: PixieDust on April 27, 2020, 05:45:46 amWhy? I worked with higher frequency clocks than that back when I had only a 100MHz scope.Sure, the signal was not displayed exactly accurately, but the signal is *never* displayed exactly accurately, there is *always* some distortion to the measured signal no matter how much bandwidth you have. Most of the time in the real world it simply doesn't matter. You can see what you need to see, you know that the corners of the pulses are getting rounded off a bit by the limitations of the scope and you mentally account for that. You always need to understand the limitations of your instruments and know how to interpret what it's showing you, this is true no matter how good they are, ALL instruments have limitations.Having a 300MHz scope is nice, but in most cases you don't NEED a 300MHz scope, unless your interest is only in displaying the nicest squarest square waves you possibly can. When I look at a clock signal I'm interested in seeing the frequency, amplitude, DC offset, and whether the waveform looks reasonably clean, either squarish or a sine wave. The fact that a high frequency square wave starts to look a bit round is not a problem, I can still see if something is really wrong with it. There are cases where something needs a really fast rise time but they are rare, at least in the things I've done.

author: tggzzz
author_rank: Super Contributor
timestamp: April 27, 2020, 04:53:01 pm
content: Quote from: james_s on April 27, 2020, 04:01:42 pmTo have confidence that the receiver will correctly interpret the analogue voltage as a digital signal, you also need to be able to see over and undershoot, whether the transition is monotonic, glitches, and the setup and hold times.Once that is assured, you might as well flip to the digital domain and use a logic analyser.

author: james_s
author_rank: Super Contributor
timestamp: April 27, 2020, 07:33:08 pm
content: Quote from: tggzzz on April 27, 2020, 04:53:01 pmBut how often is this really an issue? Sure there are times when it matters, and high bandwidth scopes exist because of this, but how many hobby projects are going to be scuttled because 100MHz is not enough? What projects are people building where 60+MHz external buses are being used? Even if you're using a 60MHz clock to drive the processor most of the external buses are going to run at much lower rates.A high bandwidth scope is a luxury, it's definitely nice to have, but to say one NEEDS hundreds of MHz for typical hobby projects is ridiculous, until very recently such exotic instruments were well out of reach of the vast majority of hobbyists. Again ALL scopes lie to you to some degree, you need to understand the limitations of your scope and the ways in which it lies.

author: tggzzz
author_rank: Super Contributor
timestamp: April 27, 2020, 09:05:21 pm
content: Quote from: james_s on April 27, 2020, 07:33:08 pmFor some tasks, as I've noted, there is no substitute for the bandwidth stated. If the task is not relevant then you don't need the bandwidth. With skill and imagination it can be possible to avoid using scopes at all!But if you don't need to investigate digital signal integrity, then why use a scope? Why not use a logic analyser, which is typically much cheaper?So, if you are repairing broken equipment, you probably don't need a fast scope: usually a DVM is sufficient.If you are a competent systems engineer and know how to interconnect components, again a DVM is probably sufficient.If you are debugging an arduino, then you probably use print statements.If you are debugging something other than digital signals, then use the characteristics of those signals.But my experience is that non obvious symptoms in digital systems can often be traced to signal integrity problems.

author: SilverSolder
author_rank: Super Contributor
timestamp: April 27, 2020, 10:35:17 pm
content: Even when working with an Arduino, a scope is a huge time saver - for looking at PWM waveforms, or looking at an I/O pin that you are flipping from code, looking at input voltage waveforms from sensors, etc. etc. etc. - it is a natural step for an Arduinado to take once they get to a certain level.

author: james_s
author_rank: Super Contributor
timestamp: April 27, 2020, 11:07:33 pm
content: Quote from: tggzzz on April 27, 2020, 09:05:21 pmBecause a scope can show you more, even a scope with less than the ideal amount of bandwidth needed to (almost) perfectly render the signal. It's not like it just suddenly goes from perfect to unusable as you approach the bandwidth limit. An ideal square wave has an infinitely short rise time, you can pretty easily generate a signal that requires a 1GHz+ scope to image accurately and even that will not be 100% accurate unless you have a scope with infinite bandwidth.More is always nice, but this common blanket statement "you need xxx MHz of bandwidth to work with a 50 (or whatever) MHz signal is bs. Sometimes you do, often you can get by just fine with less, it depends.

author: PixieDust
author_rank: Frequent Contributor
timestamp: April 28, 2020, 06:22:00 am
content: Quote from: james_s on April 27, 2020, 07:33:08 pmMy foray into electronics was related to LCD displays. I bought the first scope that was listed on ebay. I had no idea what bandwidth it was, in fact I think I mistook 250MS/s as it's bandwidth. Turned out to be a 100Mhz scope and a equivalent time mode 300Mhz for repetitive signals. At 100Mhz, everything looked ok, but the LCD didn't work, in repetitive mode, the signal was obviously broken (sorry, don't have photos any more, my phone died and all my photos were lost) and explained why the LCD wasn't working. If it wasn't for sheer dumb luck i.e. that my scope could work at 300Mhz, I would have incorrectly assumed that the clock was ok and who knows how long it would have taken to troubleshoot the problem.If you can afford a higher bandwidth scope like OP suggested he was in such a position, I would suggest to go as high as the wallet allows. You can always use the scope in that oddball occasion that you never anticipated, but you can't ever go higher if you skimp on your equipment. I'm only suggesting this in situations whereby you can afford it, otherwise I agree, get the right tool for the job, but again OP sounded like he wanted to splurge a bit.

author: rstofer
author_rank: Super Contributor
timestamp: April 28, 2020, 06:48:56 am
content: AFAICT, the only reason for buying an analog scope is bandwidth. Advanced features are all going to favor the DSO.About a dozen years ago, I bought a used Tektronix 485 from eBay for a couple of hundred bucks. I used it for about 10 years until I bought the Rigol DS1054Z. The 485 now just sits under the bench waiting for me to come up with a project requiring a higher bandwidth scope.Although most of my FPGA projects run at 100 MHz, seldom do off-chip signals run anywhere near that fast. I might run SPI at 10 MHz but everything else is much slower.How much bandwidth do I need... Sure, more is better but, for me, 100 MHz is adequate. An SDS1104X-E, unlocked to 200 MHz would be nice...The Analog Discovery is only 30 MHz with probes and 9 MHz with flyleads yet it seems more than adequate for the kinds of things I am working on.

author: tggzzz
author_rank: Super Contributor
timestamp: April 28, 2020, 09:17:48 am
content: Quote from: PixieDust on April 28, 2020, 06:22:00 amThat's a classic example of a signal integrity problem, and the important difference between front-end bandwidth and sampling rate.Lovely story, thanks for sharing it with us

author: tggzzz
author_rank: Super Contributor
timestamp: April 28, 2020, 09:23:03 am
content: Quote from: SilverSolder on April 27, 2020, 10:35:17 pmOf course, but there is an important difference between "like" and "need".Getting into the thought processes of how to do more with less can beveryvaluable whendesigning instruments that are performance leaders, e.g. what scope do you use to debug a Keysight DSAX96204Q (2*63GHz channels, 160GS/s)when ideal equipment simply isn't available, e.g. too expensive, long lead time, not physically available

author: tggzzz
author_rank: Super Contributor
timestamp: April 28, 2020, 09:26:23 am
content: Quote from: rstofer on April 28, 2020, 06:48:56 amAnalogue vs digitising is irrelevant in this context.I too like my Analog Discovery, especially if I want to look at frequency domain traces - the 14-bit ADC is an important parameter in that use case.OTOH, my 485 is the one that sits on my bench

author: Mp3
author_rank: Frequent Contributor
timestamp: April 28, 2020, 09:45:09 am
content: I never knew about the AD and now i want oneI have a Siglent I unlocked to 200mhz even though i only use it for trivial stuff like PSU repair as well as the occasional audio signal, so i could get by with a whole lot less , in fact I don't give it nearly as much use as it really should get.

author: tautech
author_rank: Super Contributor
timestamp: April 28, 2020, 10:50:42 am
content: Quote from: Mp3 on April 28, 2020, 09:45:09 amBe careful to do your homework on the AD's input ratings as for PSU work you'll be safer to stick with the 400V input rated Siglent.

author: tggzzz
author_rank: Super Contributor
timestamp: April 28, 2020, 11:32:49 am
content: Quote from: Mp3 on April 28, 2020, 09:45:09 amDepends on what you mean by "PSU repair". If the PSU is an offline SMPS, then there are lethal voltages in some places, and in other cases putting a probe's shield on the wrong point causes smells and noises to be emitted. Hopefully such smells and noises come from the equipment, not from your body.It is beneficial to know when a HV isolating probe is necessary.

author: rstofer
author_rank: Super Contributor
timestamp: April 28, 2020, 03:32:34 pm
content: Quote from: tautech on April 28, 2020, 10:50:42 amAbsolutely! I bring this up in nearly every AD discussion because it is a really big deal to smoke the device. I even went so far as to buy a pair offixed10x probes for use with the BNC adapter. It would be a rare case for me to work on anything beyond +-15V but if I do, I'll use the BNC adapter with 10x probes.A DMM comes in handy when circuit voltage is unknown. I'm not sure how it can BE unknown but I guess there's a possibility. I think I would want to know what to expect before I jammed a probe in a circuit!

author: rstofer
author_rank: Super Contributor
timestamp: April 28, 2020, 03:50:53 pm
content: Quote from: SilverSolder on April 27, 2020, 10:35:17 pmThis is exactly the case for my grandson's "confined to quarters" summer and learning about the Raspberry Pi and it's IO capabilities (plus a wee bit about Linux and the Pi itself). One of the early experiments is a fading LED - standard fare for these kinds of programs. Intuitively, and in code, the LED should gradually increase and decrease in brightness. You can watch the LED and see what happens.But that is not at all the same as seeing the actual PWM waveform and relating it to a later experiment with a DC motor. Seeing the waveform is learning, handwaving is just guesswork. Pencil whipping we called it when I was in college.The dilemma: Do I spring for another AD2? I sure don't want to give up mine! I think this is a superior choice for the experiments. Or do I give him my DS1054Z and use that as an excuse to buy the SDS1104X-E? Hands on experience with a real scope would be a side benefit of the latter choice. Plus I get a new scope!Or, do I do both? It's only money...

author: tautech
author_rank: Super Contributor
timestamp: April 28, 2020, 08:34:30 pm
content: Quote from: rstofer on April 28, 2020, 03:50:53 pmHmmm, bit of envy here as our step grandkids, the only ones old enough to have any interest in 'tronics are in Perth a 7 hr flight away.

author: rstofer
author_rank: Super Contributor
timestamp: April 28, 2020, 10:41:15 pm
content: Quote from: tautech on April 28, 2020, 08:34:30 pmMy grandson lives a few miles away and is attending a local university about 2 blocks from home. He is just wrapping up a mandatory "Circuits" course even though his major is ME. The course is pretty comprehensive, they were up to Laplace Transforms about half way through. Pretty impressive for a 1st semester EE course. They used the AD2 for lab classes so he should be pretty good with the device. The tendency is to get him signed up as a student at Digilent and buy one of the AD2 bundles with the discount. If he gets along well with the Pi and the various experiments, we can discuss a scope. The scope is given, the SDS1104X-E. The question is: which of us gets it!

author: vk6zgo
author_rank: Super Contributor
timestamp: April 28, 2020, 11:34:54 pm
content: Quote from: rstofer on April 28, 2020, 03:32:34 pmSwitchable 1x/10x probes are an invention of the devil!.Unfortunately, they seem to have become the standard.

author: SilverSolder
author_rank: Super Contributor
timestamp: April 29, 2020, 01:29:52 am
content: Quote from: tggzzz on April 28, 2020, 09:23:03 amAgree - "doing more with less" approaches art and beauty when done well.

author: SilverSolder
author_rank: Super Contributor
timestamp: April 29, 2020, 01:36:02 am
content: Quote from: rstofer on April 28, 2020, 10:41:15 pmThe AD2 idea is really good. I would have loved one of those when I was a kid. It really packs a whole shelf full of boat anchors into a very small and affordable space, and there is so much to learn and understand. If I had to choose between a scope and an AD2, I would take the AD2.

author: rstofer
author_rank: Super Contributor
timestamp: April 29, 2020, 01:48:28 am
content: Quote from: vk6zgo on April 28, 2020, 11:34:54 pmThey were probably invented by the scope manufacturers.

author: tggzzz
author_rank: Super Contributor
timestamp: April 29, 2020, 03:20:55 pm
content: Quote from: vk6zgo on April 28, 2020, 11:34:54 pmI keep on telling people that, but it takes them a while to gain the experience to agree withmeus.

author: mrflibble
author_rank: Super Contributor
timestamp: April 29, 2020, 04:28:01 pm
content: Quote from: tggzzz on April 29, 2020, 03:20:55 pmThey are a great teaching aid though!

author: PixieDust
author_rank: Frequent Contributor
timestamp: April 30, 2020, 08:00:33 am
content: Quote from: tggzzz on April 27, 2020, 07:06:55 amIt's also discussed here + how to calculate system bandwidth:Quote from: Mp3 on April 28, 2020, 09:45:09 amWhat's AD btw?

author: tggzzz
author_rank: Super Contributor
timestamp: April 30, 2020, 09:59:56 am
content: Quote from: PixieDust on April 30, 2020, 08:00:33 amThat's fine, but it doesn't ram home the fundamental point that the required bandwidth (0.35/tr) is the same even for a 1Hz or less signal.Consider, for example, a once-per-second watchdog pulse with a 1ns risetime. There is no point in analysing that signal and thinking you need a 5Hz bandwidth!More concretely, consider the 1pps signal coming from most GPS receivers.QuoteDigilent's Analog Discovery

author: PixieDust
author_rank: Frequent Contributor
timestamp: May 04, 2020, 11:54:24 am
content: Gocha.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: May 09, 2020, 07:53:07 pm
content: I would not easily buy an oscilloscope without screen and knobs, or I'd buy it maybe just as a toy or for very special purposes.I sorta like the MicSig portable scopes. The older versions only have a touch screen, while recently there is at least one model which both has a touch screen and knobs. MikesElectricStuff has made a nice review of this scope.You may like it because it's very flat and needs a small storage area. There are also portable versions which run for several hours on a battery.