WTB: My first oscilloscope - Page 1
Forum section: electronics / general

author: dustmason
author_rank: Contributor
timestamp: July 29, 2014, 06:28:46 am
content: Hi all,I've spent some time over the last few days searching and reading my way around this forum. I've decided that its time to pick up an oscilloscope, but as I've never used one before I am taking my time to learn all I can before I buy.I'm a software guy who has recently discovered a love for electronics. Like many others, the Arduino was my gateway. I still love working with Arduinos and similar uC boards but have also started educating myself in EE basics. I'm into vintage electronic instruments and would love to create my own simple synths and drum machines.My daily routine includes searching eBay for an affordable and fully functional analog scope, but I've been too hesitant to complete a purchase so far. I also keep an eye on craigslist but nothing great has materialized.Does someone on this forum have a decent, working older scope they would like to sell me? I'm in the SF Bay Area of California, USA. I'm ready to spend up to $400 or so if a great deal comes along. I've read often on this forum that I should be able to find an old scope for $100 but I don't feel confident enough to buy one like that from eBay. I figure a 2-channel, 50-100MHz unit would suit me well. Maybe you've come across one on eBay or craigslist that looks good - share the link!I read on the Rigol website that the DS1052D includes a logic analyzer (http://www.rigolna.com/products/digital-oscilloscopes/ds1000d/ds1052d/). This sounds great to me, as I have built a few projects that utilize I2C and SPI components. There were times that being able to capture serial data over the wire would have been fantastic. Many of my future projects will involve digital circuits. Do you think this would be a good purchase? I'm unable to find any reviews online.Thanks

author: David Hess
author_rank: Super Contributor
timestamp: July 29, 2014, 03:50:18 pm
content: The San Fransisco area is one of the better places in the world for finding used test equipment within driving distance and in good shape but given your price range, needs, and current capabilities, I think a new instrument with a warranty is what you should look for unless you are prepared to spend time refurbishing an old instrument for the learning experience.

author: dustmason
author_rank: Contributor
timestamp: July 29, 2014, 04:42:01 pm
content: Thanks for the tips. I won't go for the Rigol with the built-in LA.A new oscilloscope sounds good to me – according to what I've read the Rigol DS1052E is very often recommended to people like me. Is that still true now, some 5 or 6 years (i think) since it was released? I've read a little bit about the DS1052E and while it looks capable I would be happy to spend another $100 or so to get something with a nicer display and some fancier features.

author: dustmason
author_rank: Contributor
timestamp: July 29, 2014, 05:43:10 pm
content: Thanks gazelle, that DS1074Z looks nice although stretches my budget a little. I might go that route but I'm gonna keep hunting for a bit first.I found this craigslist postinghttps://sfbay.craigslist.org/eby/ele/4591474965.html. Its light on info but I emailed the seller asking for confirmation that everything works. They told me that they will test it over the next few days and let me know. What do you guys think of that listing? What specific questions should I make sure to ask?

author: David Hess
author_rank: Super Contributor
timestamp: July 29, 2014, 05:49:08 pm
content: That is probably not a bad deal given all three instruments. I have a 2246 and they are nice without any significant failure modes other than age and full service documentation is available.Despite the look though, that is an analog oscilloscope and not a DSO although it supports measurement cursors and some automatic measurements. The extra 2 channels are very useful for logic level measurements and triggering.I have seen many good instruments advertized through the San Fransisco Craigslist over the years.

author: edavid
author_rank: Super Contributor
timestamp: July 30, 2014, 04:50:06 am
content: Quote from: dustmason on July 29, 2014, 05:43:10 pmOverpriced by 2-3X.

author: dustmason
author_rank: Contributor
timestamp: July 30, 2014, 06:26:37 pm
content: Overpriced eh? $500 is more than I was hoping to spend but I thought that was a solid scope. I do believe that the bay area is a great place to find scopes but I've not had great luck so far. Here's what the current crop on craigslist looks likehttps://sfbay.craigslist.org/search/sss?query=oscilloscope&s=0&sort=rel. Some sub-$100 choices on there but I don't know enough to separate the good from the ugly

author: KJDS
author_rank: Super Contributor
timestamp: July 30, 2014, 07:13:30 pm
content: These two look the best valuehttps://sfbay.craigslist.org/sby/ele/4583965491.htmlhttps://sfbay.craigslist.org/sby/ele/4593955842.html

author: dustmason
author_rank: Contributor
timestamp: July 30, 2014, 07:22:47 pm
content: Thanks KJDS, I just emailed the seller of the 2465. Looks to be a much better deal than my previous find...

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 30, 2014, 09:24:41 pm
content: Quote from: dustmason on July 30, 2014, 07:22:47 pmI would look for a TEK 2232...

author: dustmason
author_rank: Contributor
timestamp: July 30, 2014, 09:27:40 pm
content: George, why do you say that?

author: David Hess
author_rank: Super Contributor
timestamp: July 30, 2014, 09:41:56 pm
content: I would consider the two that KJDS linked. If you are up to some minor diagnostics and repair, this 465 would be a good deal as well:https://sfbay.craigslist.org/pen/ele/4556140200.htmlI am not sure what is wrong with it I suspect it would be easy to fix.As far as recommending a 2232, that is almost the oldest DSO which I consider completely useable although it does not have automatic measurements. They are probably a little more difficult to repair than the 465 I linked.

author: dustmason
author_rank: Contributor
timestamp: July 30, 2014, 09:54:32 pm
content: Thanks very much for all the input. A little bit more reading makes it seem like the 2465A is pretty ideal as far as old analog scopes go, so I'm gonna go for it. $160 is well within budget.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 30, 2014, 10:03:25 pm
content: Quote from: dustmason on July 30, 2014, 09:27:40 pmBecause the 2232 and the 2221A (note the A, it's important!) are the best of the 22xx series, are both true analog and digital scopes, can be found much cheaper than that rigol, and I've had my 2232 for 20 years and it's still alive and kikin' and I still use it often and love using it very much. I've also got one of these Rigol 1000zs that somebody recommends a few posts above and it's great and modern and blah blah blah, but a tektronix is a tektronix :-)For example, you're looking at something and you want to save it and look somewhere else, well, to save the wave in the TEK you push the save button and the memory # button and you're done. To do the same on the rigol you've got to go through a seemingly endless sequence of clicks an menu items and/or knobs. What ends up happenning is that on the rigol you never save a reference.Another plus is that the 2232 belongs to the end of an era when the Teks still had a knob or a button for each and every thing, so that everything is at most a single click or knob away, and when you're used to your scope that's simply great. Not so much when you're still not used to it :-)In California you are going to be able to get one for less than $200. I've had to pay that much just to have my 2nd and 3rd 2232s shipped to Spain.

author: David Hess
author_rank: Super Contributor
timestamp: July 30, 2014, 10:05:07 pm
content: Quote from: dustmason on July 30, 2014, 09:54:32 pmThe 2465A is a really nice oscilloscope although later models in that series are known to have some problems.The 2465A stores its calibration data in lithium battery backed up CMOS SRAM. If the battery goes dead or the calibration data is lost, then the oscilloscope needs to be recalibrated which is *not* a trivial exercise. Earlier models used an EEPROM like memory and later ones used Dallas NVSRAMs.

author: dustmason
author_rank: Contributor
timestamp: July 30, 2014, 10:09:54 pm
content: George - good to know, i would definitely consider a 2232 if one popped up soon.DavidHess - thanks for the tips, also very good to know. as a complete newcomer to scopes in general (as i said, i've never used one) what should i do to make sure this 2465A is still calibrated?

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 30, 2014, 10:17:40 pm
content: Quote from: David Hess on July 30, 2014, 09:41:56 pmYes but not the analog part of it, only the logic pcb, and that is hard to break.I have a 465B too, it's made 99.9% of discrete parts, easy to repair and a pleasure to use, but as it's only analog it's pretty useless when you're dealing with non repetitive signals!

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 30, 2014, 10:34:06 pm
content: Quote from: dustmason on July 30, 2014, 10:09:54 pmSooner or later you're going to need to look at some signal that happens just once, for that you need a digital storage scope. A reset pulse, a character coming out of a serial port, etc. An analog scope is almost useless for that (*). If this is going to be your only scope for a while you're going to regret buying an analog only scope. Trust me you want an analog scope with digital storage.(*)You will end up sending the characters in loops, just to be able to see them in the scope.

author: dustmason
author_rank: Contributor
timestamp: July 30, 2014, 10:39:08 pm
content: George - what you are saying makes good sense. For example, debugging serial communication is something I already feel the need for today. However I didn't mention that I pre-ordered a new Logic 8 analyzer from saleae yesterday. I think something like that would be a better tool for that task anyway, right? With a Logic 8, do you still think I should spring for a DSO over a purely analog scope?

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 30, 2014, 10:47:48 pm
content: Quote from: dustmason on July 30, 2014, 10:39:08 pmThe saleae will work fine if and only if the signal you're looking at is ok. If, for example, the amplitude is half what it should be, the saelae is not going to work at all, but the scope will let you see why/what's going on. The thing is, if you can buy a good analog scope that turns into digital at the press of a button, why would you want go for the one without the magic button?

author: dustmason
author_rank: Contributor
timestamp: July 30, 2014, 10:54:24 pm
content: OK I see what you mean. I was hoping that the "analog" inputs on the new saleae would help mitigate this kind of issue, but I think I understand that a real scope is always going to be a better tool for visualizing that kind of problem.I would definitely rather have a DSO instead of a purely analog scope. I just need to find a little more patience and keep looking for something like a 2232

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 30, 2014, 11:08:21 pm
content: Quote from: dustmason on July 30, 2014, 10:54:24 pmIf the saleae inputs are analog (I didn't know that) then it's sort of a digital storage scope and what I said then doesn't apply. But I'd still go for a scope with the magic "analog/storage" button. Without the analog part you can't see oscillofun.flac in its full glory.

author: dustmason
author_rank: Contributor
timestamp: July 30, 2014, 11:20:48 pm
content: Like I said, I am pretty new to this world, so I might have it wrong. The Saleae website describes the new (shipping soon) Logic units as having analog inputs, but as you might expect, the sample rates and max bandwidths are pretty low compared to a proper scope. For example the max analog sample rate on the model I ordered is 10 MS/s (bandwidth 1MHz). For the applications I've been messing with so far (I2C, SPI, MIDI and basic serial protocols) I feel like that is good enough. The digital sample rates / bandwidths are much higher (100MS/s and 25MHz).All of that said, I will take your advice and be patient. Feel free to share links to good deals on DSOs you might find! I appreciate all the help

author: David Hess
author_rank: Super Contributor
timestamp: July 31, 2014, 12:49:38 am
content: Quote from: GeorgeOfTheJungle on July 30, 2014, 10:17:40 pmBeyond just simply being more complex, the 2232 switching power supply has some odd failure modes besides just the aluminum electrolytic capacitors wearing out with age. But I agree that the analog part is pretty straightforward and since the oscilloscope shares so much with some other oscilloscopes in the 22xx series, parts are easy to come by . . . except for the bezel switch assembly. :/

author: David Hess
author_rank: Super Contributor
timestamp: July 31, 2014, 12:55:13 am
content: Quote from: dustmason on July 30, 2014, 10:09:54 pmI think the 2465A will complain (but still function) if the calibration data is lost but one thing I would do upon receiving one besides functional tests is check the date on the lithium backup battery.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: July 31, 2014, 01:38:55 am
content: Looks like you have gotten some good advice. If you change your mind about the DS1074Z do know that TEquipment gives a 6% discount to EEVBlog members (mention it to them to get a coupon code). Also, the DS1074Z is more expensive but it is also a MUCH more capable unit overall. Now of course many of the tradeoffs between digital and analog apply but many are dramatically lessened with the Intensity Gradient aka Digital Phosphor display. Also, the Rigol is hackable in that you can get the basic DS1074Z an hack it to add (100Mhz, advanced triggering, 24MPt memory, Data recording, data decoding (I2C, SPI, etc.), an unofficial 500uV sensitivity mode that is a bit buggy). The triggering is one area where modern digital scopes shine compared to the older analog scopes. On an older analog scope you could trigger on height, slope, TV and occasionally a few other variations on those. Modern scopes have loads of triggering to more easily capture transients which are causing bugs. On the rigol you can trigger on : edge, slope, pulse, pattern, CAN, USB, FlexRay, RS232/UART, I2C, SPI, Runt, Windows, Nth Edge, Delay, Time Out and I think a few more. Some of these triggers come from the Advanced Triggering package which you can hack on. This ability to trigger on digital interfaces can be useful when trying to find particular bugs. Similarly, the 24MPt of memory allow you to trigger and just record until you find the glitch occurring.This is not to say that this is the way you must go or should go. You know your budget and needs better than me. This is just something I thought should be mentioned. As I said, you have received some good advice so far, I just wanted to add a bit more to the conversation.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 31, 2014, 09:43:57 am
content: Quote from: dustmason on July 30, 2014, 11:20:48 pmI think that with a good scope on the bench you're going to find little use for the saleae. In 30 years I've never come across a problem that required a logic analyzer. Perhaps that's because I've never had one. Not even now that they're cheap.Yes 8+ signals on screen at once looks cool, but its very rarely something you *need* to see, if ever. I got the DS1074z in April to have at least one scope with 4 channels, but channels 3 and 4 are still virgin, huh.The only negative thing I can say about a 2232/2221A is that once you try a small one like that rigol you begin to notice how big a chunk of bench the 2232 requires. But you're about to discover that that tiny saelae takes up a lot of space as well because without a laptop it's useless.On the other hand the databooks now are .pdfs, and the .pdfs are a google search away, and we can't live without checking the email at every minute, and may want to do a quick check in LTSpice, or google something else, so a laptop on the bench is something you're going to want to have anyway.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 31, 2014, 09:58:57 am
content: Quote from: David Hess on July 31, 2014, 12:49:38 amThe SCR/preregulator/FET current limit board you mean, right? If so, yes, I still have a 2215 with the disease. It works if I bypass that and feed it directly from an external DC power supply. I haven't figured out yet the fix, but there are not any custom parts in there I think, everything are discrete easy to find parts, so I'm not too worried about it.The bezel switch assembly is that below the CRT, with the 5 save ref push buttons? Mine are fine, but I'll touch wood :-)

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 31, 2014, 10:13:41 am
content: Quote from: dustmason on July 30, 2014, 11:20:48 pmI've found that the "make offer" button in ebay is much much more useful than what I thought :-)

author: David Hess
author_rank: Super Contributor
timestamp: July 31, 2014, 01:12:03 pm
content: Quote from: GeorgeOfTheJungle on July 31, 2014, 09:58:57 amThe 2213 and 2215 are distinct from others of the 22xx series and are the only ones that used the SCR preregulator and FET current limiter. They have their own issues like generating too high a CRT filament voltage for which Tektronix issued a change notice but they seem to be pretty reliable.The 2213A through 2232 series (and the later 24xx oscilloscopes) have a universal input switching FET preregulator driving a saturable core inverter. Over at TekScopes@yahoogroups.com we have had a couple that defied diagnostics and repair despite the design being pretty straightforward but of course off-line regulators are inherently difficult to scrutinize because of safety issues. The bad ones tend to run for a while and then self destruct again without damaging the oscilloscope. I have not been able to get my hands on one to find out what is really going on.The 2201 through 2225 series have a different power supply design yet which which uses a 60 Hz transformer for step down and isolation before a low voltage buck preregulator and non-saturable core inverter and they seem to be more reliable. I would have expected them to have problems with their voltage driven inverter but apparently that has not been an issue. Maybe there are just fewer of them.QuoteI have a 2232 which needs a replacement bezel switch assembly. The silver traces on the flexible printed cable tend to fail after a while and the only oscilloscopes which used that part are the 2221A, 2224, and 2232.Some are repairable with conductive ink but it is difficult.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: July 31, 2014, 03:39:30 pm
content: Quote from: GeorgeOfTheJungle on July 31, 2014, 10:13:41 amQFMFT! I have also found that even it doesn't say make offer, a messaged offer often works as well.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 31, 2014, 10:55:37 pm
content: Quote from: David Hess on July 31, 2014, 01:12:03 pmDavid, interesting and very useful, thank you!