How much scope is too much scope? - Page 1
Forum section: electronics / beginners

author: yada
author_rank: Frequent Contributor
timestamp: May 06, 2017, 05:45:25 pm
content: I'm trying to buy a scope and really have no idea if its going to suit my needs or if I'm looking at what it can do and seeing that this is ore so this is better. But really how much of that stuff would you use? Bandwidth and sampling rate etc. Do you really need 200 MHz if your just building transistor circuits and 555 timers, but what if you do RF stuff? I'm building a lot of simple* RF circuits and it would be nice to just plug in a scope and see if its oscillating. If I'm using transistors that go up to 1GHz how much scope do I need? Every time I'm about to buy a scope I see a new thread that shows a "better" scope for the money. This seems to be a huge question among beginners and many are afraid they wont know until after they just spent several hundred dollars and found they have features they will never use and things they cant do because the scope doesn't have that function. Do most modern scope come with signal generators? Do you even want that in your scope or is it better/ more practical to have a stand alone? There are sticky thread but most are so long that the relevant info is lost or they go off on tangents.

author: Cliff Matthews
author_rank: Unknown
timestamp: May 06, 2017, 05:59:50 pm
content: So you've seen the other threads. In some cases experience now means career success sooner, so why not just jump on a commodity scope (DS1054z?) and re-sell if it doesn't fit? The delay may cost even more.

author: Howardlong
author_rank: Super Contributor
timestamp: May 06, 2017, 06:06:08 pm
content: What is your budget?What do you mean by RF? Ready made modules or are you rolling your own? At what frequencies? What sort of modulation, is it analogue or digital?Irrespective, for RF, in general a scope is often not the go to tool of choice, but for HF and low VHF you can make do sometimes, it depends what you're tring to do.For RF, a comms test set is very often a far more useful tool, including signal generator, power meter and sometimes spectrum analysis and a few even tracking generators for filter measurement.

author: rstofer
author_rank: Super Contributor
timestamp: May 06, 2017, 06:56:47 pm
content: Two channels versus 4?Simple circuits can get by with 2 channels, uC projects might better use 4.You can't have enough bandwidth, no matter how high it is. But cost becomes a factor at some point.Bandwidth is more important if you use square waves. You need to display a bunch of harmonics that aren't necessary with sine waves.Do you really need to see very high frequencies or do you just want to see the spectrum analysis. Different tool...I would start with something simple like the DS1054Z or the new Siglent SDS1202X-E

author: retrolefty
author_rank: Super Contributor
timestamp: May 06, 2017, 07:20:45 pm
content: Like it or not, if you continue in your interest in electronics, your first scope purchase will not be your last scope purchased. Stop trying to optimize your decision, just go with something popular that is comfortable to your wallet and be done with it. For now...

author: yada
author_rank: Frequent Contributor
timestamp: May 06, 2017, 07:47:43 pm
content: Quote from: Cliff Matthews on May 06, 2017, 05:59:50 pmWhat does that even mean? Reselling something takes time and usually a loss especially when you turn something new into something used.My budget is about $400USD (since most things arnt in CAN on forums). The RF circuits are all under 1GHz for now. A signal generator would be good for testing stages in an RF circuit but can you use the same scope that's making the signal to measure the signal? I'm not really advanced enough to look for packets in a digital signal so I guess that doesn't matter. I also want to learn more with transistor circuits and I'm always curious to see what the signal is doing between components. I learn best by trial and error or building things then changing out random pieces or values. For instance in my motorbike turn signal circuit I totally removed what I thought was an absolutely necessary transistor's (collector?) resistor in one stage and the circuit still works. Everything I know says that it either shouldn't work or at least stop at that stage. I think a scope would tell me why this is. But don't et too hung up on the fact I'm experimenting with RF stuff. I might get hung up on something as I learn more and decide that I would rather build other circuits. That's what makes this difficult, people ask very specific question as to what you are doing at the moment instead of thinking about the range of things you would do with it. Just because I'm building a circuit now that might need a very specific function of a scope doesn't mean I want to invest and extra 100$ just to build that one circuit and have a piece of equipment I'll never use again.

author: abraxa
author_rank: Frequent Contributor
timestamp: May 06, 2017, 07:57:48 pm
content: Quote from: retrolefty on May 06, 2017, 07:20:45 pmI somewhat agree. While I do think one should confirm that the scope that is currently popular has specs that are ok for one's own use cases, it does definitely make the decision easier. Having a scope - *any* scope really - at home to use will teach you what you like, what you don't like and what you miss in that particular one, making you all the more knowledgeable when it's time to get a better/newer one. Unless you're willing to drop $2000 or more on it, I'd just go with a basic model to practice with.Small note regarding 2 vs. 4 channels, btw: in A-B mode, you can create a makeshift differential probe using two channels if both signals are referencing a common ground. If you have a 2 ch scope, this A-B signal would be all you see. With a 4 ch scope, you can either add two other signals or another makeshift differential signal for comparison.

author: rx8pilot
author_rank: Super Contributor
timestamp: May 06, 2017, 08:06:47 pm
content: Focus on learning. Buy the most capable scope you have the cash for. You will almost certainly outgrow just about any entry level scope fairly quick. When you replace the first one - you will have far more knowledge of what is important to you.Like others have already said - don't fiddle around and waste time examine every pro and con of a $400 scope. Make a reasonable effort, come to terms with the reality that you will have regrets shortly after - and learn some electronics.A direct answer - too much scope is likely far outside of your budget.

author: rstofer
author_rank: Super Contributor
timestamp: May 06, 2017, 09:26:33 pm
content: Quote from: yada on May 06, 2017, 07:47:43 pmIt means that education is never free! Yes, you will sell for less than what you paid but the difference is 'education'. You learned a lot of stuff while using it (which has a value) and whatever residual value exists can then be applied to the next scope. The 'education' helps you select the next tool. You will know which features you care about.QuoteThen you aren't within a decade or two of buying a 1 GHz scope. Look around! Keysight, Tektronix, etc. Not that it applies but here is a 1 GHz Keysight for about $16,000.http://www.keysight.com/en/pdx-x202189-pn-MSOX3104T/mixed-signal-oscilloscope-1-ghz-4-analog-plus-16-digital-channels?nid=-32541.1150366&cc=US&lc=engFor $400, you are stuck with entry level scopes and one of the more often recommended is the Rigol DS1054Z. After the first firmware revision (hopefully), the Siglent SDS1202X-E will be a nice 2 channel 200 MHz scope. At the moment, the Rigol OWNS the low end market. There's a reason for that!QuoteThe scope internal signal generators are not very sophisticated. An RF signal generator isn't much of an expense ($179)http://www.newark.com/tenma/72-585/rf-signal-generator-frequency/dp/66F3578It also isn't as sophisticated as some of the high frequency arbitrary waveform generatorshttps://www.rigolna.com/products/rf-signal-generators/QuoteThere is no perfect scope when budget is finite. Even if you work on RF, you are seldom interested in the carrier, you want to see the modulation. Or you want to see the spectrum and a scope is the wrong tool.https://www.rigolna.com/products/spectrum-analyzers/I don't work on RF (although my logic circuits run at 50-100 MHz) but I do have one of the less expensive RF signal generators (above) to help align an AM-FM radio kit I bought for my grandson. I also have a nice Siglent arbitrary waveform generator but it only goes to 80 MHz and that is more than I will ever need.http://www.siglent.com/ENs/prodcut-detailxx.aspx?id=1134&tid=16&T=2Two different tools, two different areas of application.For your budget, you are pretty much constrained to the Rigol DS1054Z or that Siglent SDS1202X-E. I might hold off until the first firmware update on the Siglent but the Rigol is pretty well understood at this point. It isn't perfect but it is inexpensive.There are $300k scopes and I'll bet they work pretty well. I'll never see one or even drive by a building that has one!

author: Cliff Matthews
author_rank: Unknown
timestamp: May 06, 2017, 11:26:17 pm
content: Quote from: yada on May 06, 2017, 07:47:43 pmBy "commodity scope" I meant widely available (a market staple, common, an easy re-sell, all that..). It's not sugar, wheat, rubber, fuel oil, or cattle so yeah I was off a bithttp://whatis.techtarget.com/definition/commodity

author: rstofer
author_rank: Super Contributor
timestamp: May 06, 2017, 11:36:34 pm
content: Quote from: Cliff Matthews on May 06, 2017, 11:26:17 pmYou left out 'pork bellies'; my favorite on the early morning commodities report.

author: danadak
author_rank: Super Contributor
timestamp: May 07, 2017, 12:32:14 am
content: If you are doing a lot of RF work much of it is not about timing, moreon simple basics, like amplitude, phase, spectral content.Tek made a real time analog scope, 7104, still see in used sales.It takes plugins, everything from digitizers to curve tracer to spectrumanalyzer to high G hi CMR diff amp. Be careful, not all 7000 seriesplugins will work with 7104, just most. It is real time 1 Ghz with a7A29 plugin.Note some plugins getting scarce hence get a little pricey. but to start witha basic time base and vert plugin and mainframe you can get them roughly$ 200 to $ 400.7000 series also have sampling plugins that will get you to 10 Ghz.http://www.barrytech.com/tektronix/tek7000/tek7000scopes.htmlRegards, Dana.

author: KE5FX
author_rank: Super Contributor
timestamp: May 07, 2017, 12:38:46 am
content: Did the probes cost more than the scope? No? Then it's not too much scope.

author: Brumby
author_rank: Unknown
timestamp: May 07, 2017, 01:23:16 am
content: The term "commodity" is used here to describe something that is commonplace. It is neither special nor substandard - but something that performs adequately enough at an affordable price that it has been taken up by a great number of people.This popularity attests to the item as being quite adequate for a great number of users which will cover a fairly significant range of usage. As such, such a unit represents a reasonable probability of meeting anyone's entry level needs, especially when that person is learning what it is in an item that will be important to them.In a nutshell - if you don't know what you need in a scope, go with one that gets recommended. You aren'treallygoing to know what features you will need until you start using one.Quote from: yada on May 06, 2017, 07:47:43 pmDon't even worry about this. Chances are you will want to hang onto it as a second scope. Even if you do sell it, be philosophical. It will have given you knowledge and experience - as has been said, consider any loss as the cost of education.As for capabilities, you might be surprised at what you can do. It just takes time to learn and being challenged is a great way to hone your skills.Here's an example:Quote from: rstofer on May 06, 2017, 09:26:33 pmMany years ago I had a RC toy that wasn't functioning - and it fell to me to troubleshoot. The first thing I wanted to check was the transmitter which operated at 27.xxxMHz. I only had a 15MHz scope, but I thought I should still getsomethingon the screen. So I set it up and, sure enough, I was able to see the signal. The carrier was just a shaded area, but the modulation (PPM) was clearly visible. Operating the controls showed the modulation change as expected.Understanding what the specifications mean in practice is what counts. What's on paper is just a reference point.

author: rstofer
author_rank: Super Contributor
timestamp: May 07, 2017, 01:33:52 am
content: Quote from: KE5FX on May 07, 2017, 12:38:46 amThey might if they are differential probes! Those things are pricey!

author: rx8pilot
author_rank: Super Contributor
timestamp: May 07, 2017, 01:40:20 am
content: Quote from: rstofer on May 07, 2017, 01:33:52 amThe diff probe I just got was 14x the cost of my first scope. Making payments and crying myself to sleep every night.

author: David Hess
author_rank: Super Contributor
timestamp: May 07, 2017, 02:19:28 am
content: Look for an entry level inexpensive lower bandwidth oscilloscope. It will do 90% or more of what you need, give you the experience to know what to look for in your next oscilloscope, and still be useful after you have a better oscilloscope. There are only a couple of must have features:1. Get something which has standard 1 megohm BNC inputs. Anything else is either specialized or a toy.2. If a digital storage oscilloscope, make sure it has peak detection. Ignore Rigol models older than their DS1000Z series because they lie about having peak detection.3. 50MHz to 100MHz is acceptable for general use. Easily probing above 100MHz is questionable anyway.4. Instead of thinking in terms of bandwidth, think in terms of rise and fall time. 100MHz of bandwidth yields 3.5 nanoseconds which is suitable for common logic families.

author: tggzzz
author_rank: Super Contributor
timestamp: May 07, 2017, 08:46:51 am
content: Amazingly, all of the advice in this thread is sane. I'll re-emphasise it with a couple of extra points.Your first question shouldn't be "what do I need?", it should be "how do I find out what I need?". Good ways of doing that is to either get a very cheapworkingold analogue scope, or to use one in a local school/college/hackspace/makerspace, or at a local radio amateur society etc. There's a relevant saying about writing software: "plan to throw one away; you will anyhow".Don't blow all your budget on one tool; you will need a range (PSU, sig gen, multimeter, soldering iron, etc) and don't forget the cost of accessories (probes, RF leads, etc).You can't just "use a probe" to "look at" RF signals. Probes aren't "bits of wire"; they have their own "parasitic" inductance capacitance and resistance that will affect the circuit when attached. Consider, for example, that a bog-standard *10 probe with a 6" ground lead has a self resonance at about 100MHz (15pF+150nH in the ground lead). FFI seehttps://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/Look at my .sig, and realise that the gliding aphorism has a direct analogue (ho ho) in electronics.

author: rstofer
author_rank: Super Contributor
timestamp: May 07, 2017, 11:05:40 pm
content: Quote from: tggzzz on May 07, 2017, 08:46:51 amI thought it was something like "You write the best Fortran code AFTER you drop the box of cards!"

author: KL27x
author_rank: Super Contributor
timestamp: May 07, 2017, 11:12:56 pm
content: Personally, my most used tools are the easiest to use/read.E.g., I have more expensive and more accurate DMM, but the one I use the most is a 25.00 pen meter, and it has nothing to do with the specs.For scope, the main reasoning I used to justify an upgrade from a 50MHz Owon to a 70MHz Hantek was to get 4 channels. But the real improvement was the GUI/menu layout and the contrast of the screen, which is simply fantastic. If the hantek was harder to use/read, it would be in storage unless/until I needed 4 channels, and the Owon would still be living on the bech.I have in my own opinion/field/specialization/interest come to the opinion that anything between 50 and 200MHz bandwidth is pretty much useless. I don't know why Rigol users hack their scopes to get a noisy, useless bandwidth increase. It's like hacking a 1/2 mil caliper to display (useless random) numbers beyond half a mil. But even more useless (to me) due to that area of bandwidth being pretty much nothing to note.

author: tautech
author_rank: Super Contributor
timestamp: May 08, 2017, 12:30:06 am
content: Quote from: rstofer on May 07, 2017, 01:33:52 amNot like good current probes.

author: David Hess
author_rank: Super Contributor
timestamp: May 08, 2017, 02:06:02 am
content: Quote from: KE5FX on May 07, 2017, 12:38:46 amThat is one of the reasons I argue for 50 to 100 MHz being a good bandwidth for beginners or 200MHz at most. 100 to 200 MHz high impedance passive probes are inexpensive and probing is relatively easy without getting into too much trouble. Above that, probe tip adapters are needed to minimize ground lead length and expensive low impedance or active probes are needed to minimize loading.Quote from: tautech on May 08, 2017, 12:30:06 amWhen I got myLavoie LA-265Aat a garage sale for $50, it came with aP6021current probe. Does that count?

author: mtdoc
author_rank: Super Contributor
timestamp: May 08, 2017, 02:20:36 am
content: Quote from: David Hess on May 08, 2017, 02:06:02 amThe p6021s are AC only and can be found for about $100 on eBay , so $50 with a scope is a good deal. But good DC capable probes cost alotmore. Even the older Tekprobe interface A6302s go for $250 or more. I've been looking for a functional one for less than $200 with no luck.

author: tautech
author_rank: Super Contributor
timestamp: May 08, 2017, 02:42:30 am
content: Quote from: David Hess on May 08, 2017, 02:06:02 amWhen a mate picked up a P6022 for $20 here in NZ I could've cried.The 2 P6021's I got from eBay cost me a bit more than $100 US each but to replace new they're $3k+ ea.

author: David Hess
author_rank: Super Contributor
timestamp: May 08, 2017, 03:08:41 am
content: Quote from: mtdoc on May 08, 2017, 02:20:36 amNew even back then, the P6021 was about $1000. The current price for a new P6021A is about $1700.