Help choosing a scope, now or never. - Page 1
Forum section: electronics / testgear

author: Helder22
author_rank: Contributor
timestamp: October 01, 2014, 04:00:05 am
content: Hello all,Been lurking for a while now but now I really need help. Im going to be ordering a scope tomorrow after looking around for a long time.I am in a situation right now where I can buy the scope but in about 3 months I will not be able to buy anything expensive anymore because where I'm moving to the shipping and import duties are extremely high, and my income is going to drop drastically, so basically its now or never. No, moving was not my idea lol, but I have no choice. I'm already in the process of buying all the other things I think Ill need to set up a decent electronics lab: good multimeters, LCR meters, soldering stations, ESD mats, components, Panavises etc.I'm studying electronics now but I'm actually a machinist and am going to be setting up my own machine shop in the beginning of next year. Right now I'm going to be using the scope to help me learn, but it is my intention that any electronics equipment I get right now be used to supplement the machining services in the future, even if I have to hire someone more experienced to deal with the electronics side of the business for me.Since I do not know what the local market there will demand exactly (repairs, product development, etc.) I cannot say exactly how it will end up being used.I do not know if I should get the DS2072A, the MSO2072A, or the MSO2072A-S. I have about $1500 to spend immediately. My original plan was to get the DS2072A and a Rigol DP832 power supply right now, then, in a month or so, a signal/arbitrary waveform generator and maybe, if I had the cash, a logic analyzer of some kind.I read the manuals but I cannot tell, for example, if the logic analyzer built into the MSO2072A "shares the bandwidth" (not sure how to put this) with the scope. In other words, when using the Logic analyzer that's built into the scope, does that reduce the scopes bandwidth? If so, I think Id rather get a separate LA. And what about the waveform generator? Does that affect the usage of the scope itself?The price difference between the DS and the MSO is $400. Is there a LA out there for $400 that is better than the one that comes in the MSO2072A? How about an arbitrary waveform generator for the $350 price difference?I understand that its easier to answer questions like this when one knows exactly what they are going to be used for. However, in this case, by the time I finally find that out exactly I probably wont be able to get them anymore.

author: tggzzz
author_rank: Super Contributor
timestamp: October 01, 2014, 08:54:22 am
content: General principle #1: you have to make the correct decision, at the correct time. Is it really the correct time to make a decision?General principle #2: if you don't know what you want, get something very cheap and use that to learn what youreallywant and/or need. Alternatively, to repurpose Fred Brooks' famous statement "Plan to throw one away. You will anyhow".

author: Helder22
author_rank: Contributor
timestamp: October 01, 2014, 02:06:33 pm
content: Can't buy anything except junk after I move. It's take it with me now while I'm exempt from paying shipping and 100% duties + taxes or forget it.Im just gonna get the MSO version and the power supply now. Then I'll get an arbitrary waveform generator in a month or so.My General Principle is: If you're going to the desert, take lots of water. Don't wait till you get there first to discover how much water you should have taken.

author: eurofox
author_rank: Unknown
timestamp: October 01, 2014, 04:39:26 pm
content: Quote from: Helder22 on October 01, 2014, 02:06:33 pmYou are really moving to a "dark place"

author: Helder22
author_rank: Contributor
timestamp: October 01, 2014, 07:08:46 pm
content: Well, there's pretty pretty girls, good beer and sunshine, so it's not all bad.But getting stuff imported......

author: Mark_O
author_rank: Frequent Contributor
timestamp: October 01, 2014, 07:50:50 pm
content: Quote from: Helder22 on October 01, 2014, 04:00:05 amNot a bad plan.QuoteNo, the LA does not reduce the scope's performance, either bandwidth or sampling rate. And the signal generator doesn't affect the scope usage. Though having it built into the scope does (negatively) affect the usability of the sig-gen (slower, and more cumbersome, due to the shared UI and Gen control buried in menus).Quote"Better" is subjective, and also highly dependent on a variety of factors, that are impossible to assess in your situation. Everyone always wants to get "the best", even if they don't know what that is.The answer to both questions is Yes, for some combination of needs. And No for others.The MSO-part is the tougher question. If you wind up using it mostly as a protocol analyzer, there are better PA's available. And as a LA, the triggering can be done better on alternative devices. Though the memory depth on the 2072 will mitigate the weaker triggering, to some degree. OTOH, none of the alternatives, though better in certain respects, will give you correlated analog and digital traces. That can be worth a lot.The sig-gne part is easier... unless youneedit to be integrated, either for minimal bench space or portability, you're better off with a separate generator. In some ways, much better off. However, always having the sig-gen with your scope, wherever it goes, and taking no bench space can be big wins, in some situations.QuoteI think that's probably the best you can do, given the limited knowledge of your future needs. You might also spend that time pondering if you really need an arb-gen, or would be perfectly fine with a function gen. I know that arb-gen's are "the thing to have" these days, but many folks have no real need for anything beyond sine, square, pulse, ramp, noise, etc. that non-arbs can provide just fine. While there are real-world legitimate needs that make arb-gens a must for some people, a lot of other arb-gen purchasers may wind upnevergeneratinganyarbitrary waveform.

author: G0HZU
author_rank: Super Contributor
timestamp: October 01, 2014, 08:31:05 pm
content: Because you are new to electronics, my advice would be to invest the bulk of your budget in the machine shop side of the business. Surely you can buy some tools that will generate a high return on your money and use this to offset higher duty on any future scope purchase?For learning electronics I would suggest you set a budget of $200 and try and find a 'free' analogue scope, a basic signal/function generator for maybe $60 and a few cheap H/H DMMs and spend the rest of the $200 on a cheap soldering iron and various small tools and project/hobby boards from ebay (eg arduino).Buy a few 'broken things' to use as a parts source.

author: David Hess
author_rank: Super Contributor
timestamp: October 01, 2014, 08:51:24 pm
content: I would take a careful look at the differences between the less expensive 4 channel MSO1074Z and the 2 channel MSO2072A which apparently has better protocol decoding capabilities. 4 channels would be high on my list of considerations if I was going to be stuck with one oscilloscope.

author: rhost
author_rank: Newbie
timestamp: October 01, 2014, 09:35:28 pm
content: If i were just starting out learning and wanted new equipment, I would buy a Rigol DS1054Z ($400), the Saleae Logic 8 ($200), a cheap chinese dual or triple output power supply off of ebay ($150 or so), and a couple $50-$100 multimeters. One of the first projects i would do is to make a simple signal generator. I would save the rest of my money for components. All together, you could have everything you needed for under $1000 USD. You will learn a lot on the entry level equipment. Once your machine shop is off the ground and are generating income, then i would look into upgrading once you start bumping into the upper end of the various device capabilities.

author: katzohki
author_rank: Frequent Contributor
timestamp: October 01, 2014, 09:47:56 pm
content: You're not even sure what you need, but you're ready to spend $1500 on it? Wow. OK, so an oscilloscope is a good bet of something you'll need / want. LA, depends on what you are doing. If I were you I'd take the $1500 and buy surplus. Lots of surplus. You can get 2 or 3 full working test setups for that kind of money if you buy surplus. Sure, maybe you'll have to put up with older CRT-based oscilloscopes, but they won't give you information that is wrong.

author: Helder22
author_rank: Contributor
timestamp: October 01, 2014, 10:17:54 pm
content: Thanks for all the advice guys. I went ahead and got the MSO and the power supply for now.I understand what you guys are saying about me just being a beginner. But remember, I'm not buying these tools just to help with my learning process, hopefully. And I can always hire a good electronics guy to work with me if I need to. That's the plan, actually.I can not buy much more for the machine shop or I would be investing more on that for sure. But metal working machinery is very heavy. I'm already taking a Tormach PCNC 1100 cnc mill with 4rth axis, a large lathe, welding equipment, plasma cutter, compressor, band-saws, not to mention tons of other bits and bobs that go with all this stuff. The weight is becoming an issue already. All of the equipment and all of my furniture has to fit in one container and there is a weight limit. Electronics stuff weighs very little comparatively speaking, and takes up much less space.Plus, electronics is just plain FUN!

author: G0HZU
author_rank: Super Contributor
timestamp: October 02, 2014, 12:11:41 am
content: Well you now have a much better scope than I have (at home) and you have a PSU that cost probably three times the amount I have ever spent on a PSUI'm an electronics design engineer that has been in the business for >25yrs and I have a fairly decent electronics workroom at home. But so far I haven't been able to justifty the purchase of a scope as good/expensive as that Rigol or an expensive ATE/programmable PSU like the DP832

author: alex.forencich
author_rank: Frequent Contributor
timestamp: October 02, 2014, 12:37:57 am
content: Well, that's a bit of a tough situation - don't really know what you need, not much time to figure it out, and not much space to stuff it in. It's hard to go wrong with a decent DSO, though. Newer equipment will certainly be more compact than the older stuff, but it can be costly. If you plan on working with digital stuff and think you might need very long record lengths, the Saleae devices are very nice; they are not particularly expensive and have a bit more functionality than the MSO's built in logic analyzer, presuming you don't need to look at time-correlated signals. As far as the function generator goes, I would take a look at the Hantek HDG2002B. The frequency limit is software enforced, and is a thread around here on what you can do about that.Just out of curiosity, where are you located now and where are you moving to?

author: Helder22
author_rank: Contributor
timestamp: October 02, 2014, 12:40:27 am
content: G0HZUOf course you can justify it. You want it, it's your money and you've worked hard to earn it. Why is it socially acceptable for people to spend 20 or 30 times that amount on a nice car when a cheaper one would get them to work just as easily? People buy TVs for that kind of money and it's fine. Or gaming PCs. It seems that the more people want something that isn't perfectly mainstream the more guilty they feel about it and the more they feel the need to justify the expense.But, like you said (inferred, actually), you have better scopes at work. This equipment isn't going to be at home. Hopefully, it will all be at work too.

author: Helder22
author_rank: Contributor
timestamp: October 02, 2014, 12:59:51 am
content: Alex,I'm in Grenada (the little island in the Caribbean) right now. Been here for about a year and a half now. Importation duty here is high but luckily I'm exempt. Before that I was in California working as a machinist in the engineering department at the Lawrence Berkeley National Labs. Next I'll be moving to Brazil, but unfortunately not to one of the major industrial cities, so I fear a pure and simple machine shop might not have enough business to survive, that's why I'm playing it safe and adding electronics to the mix.

author: G0HZU
author_rank: Super Contributor
timestamp: October 02, 2014, 01:09:08 am
content: QuoteI guess we are all different but experience has taught me not to buy 'me' stuff unless I need the performance because usually the performance comes with baggage. i.e. higher purchase cost, extra power consumption, bigger size, more fan noise, more complicated and fussy user interface.Even at work I will usually shun the modern and powerful MDO scopes in favour of a crude old Tek TDS2012/2022 because it can still do useful work and it is quieter and smaller and uses much less power. So I can have it right next to the thing I am working on and it doesn't bug me with fan noise and it won't add much heat to the room during summer etc.In terms of the move to Brazil, you may find that there is business to be had in oldschool comms/radio servicing. But that's just a guess. If it is true then you might be wise to buy some basic (surplus, not new!) RF test gear.25 years ago Brazil was CB and ham radio crazy and you may find that this gear is still in use in remote areas. Same for taxi radios and easy to repair PMR gear?

author: Mark_O
author_rank: Frequent Contributor
timestamp: October 02, 2014, 03:00:25 am
content: Quote from: G0HZU on October 02, 2014, 12:11:41 amI wouldn't be surprised to find a correlation between those with the most knowledge being able to get more out of lesser gear, and those with no knowledge at all buying the fanciest. After all, they have no clue what they might need to do with it, so they need to be ready for anything. Even if they never do use some/most of it.There's a certain logic there, since it's less expensive to overbuy up front, than underbuy, discard, and rebuy. Better to have too much, than not enough. Especially with high-end gear becoming significantly more affordable.

author: LabSpokane
author_rank: Super Contributor
timestamp: October 02, 2014, 04:31:45 am
content: Quote from: Mark_O on October 02, 2014, 03:00:25 amI did the same Helder22 and "overbought" because the economics were there. Over the long haul, it's simply cheaper. Particularly with the 5 year warranties that are being offered.In Brazil, it's nearly 100% cellular for taxis etc. I've not seen a cb aside from the handhelds in factories.But with a 5% unemployment rate, there is always opportunity for the skilled. The Olympics in Rio have really put a crunch on for skilled workers. Wind power is still huge there, and I'm sure there's specialized machine work to be had due to the local content requirements. If you want to make money, find a business outside of Brazil who wants to sell in Brazil and that you can help with manufacturing local content.And as far as importation goes, do what all the Brazilians do and make shopping trips to Florida. If it fits in a suitcase, you're golden. It was honor system customs right up until the World Cup. And then they were only x-Ray-ing for weapons.Where in Brazil are you going? And how the heck do you *have* to go?

author: Helder22
author_rank: Contributor
timestamp: October 02, 2014, 01:52:21 pm
content: A guy has to go home at some point. To make a long story short, been away for a long time but it's time to settle down.Oh, and it's Brasilia where I'm going to btw.

author: David Hess
author_rank: Super Contributor
timestamp: October 02, 2014, 02:10:20 pm
content: Quote from: Mark_O on October 02, 2014, 03:00:25 amI am sure of the correlation and the reason for it; knowledge reveals alternatives and experience reveals what works and what does not work. In addition, lesser gear also tends to be less complicated and less obfuscated leading to more reliable results if only because of better understanding.

author: 1xrtt
author_rank: Regular Contributor
timestamp: October 02, 2014, 02:24:08 pm
content: Quote from: Helder22 on October 01, 2014, 07:08:46 pmGirls, beer, sunshine... and ridiculously expensive shipping and import fees. Sounds like home to me...Quote from: Helder22 on October 02, 2014, 12:59:51 amBingo!!

author: Helder22
author_rank: Contributor
timestamp: October 02, 2014, 02:44:13 pm
content: So you know what I'm talking about right? Get the stuff now, or cry about it later lol!

author: eurofox
author_rank: Unknown
timestamp: October 02, 2014, 03:01:47 pm
content: Quote from: Helder22 on October 02, 2014, 02:44:13 pmMaybe you will get so rich with your new business and have 3 girls on you lap and plenty of beer that you will not care about the outrageous duty's

author: 1xrtt
author_rank: Regular Contributor
timestamp: October 02, 2014, 04:12:45 pm
content: Quote from: Helder22 on October 02, 2014, 02:44:13 pmYes I do. I also agree with the "bring lots of water to desert" strategy, but the downside is that you will overspend, inevitably.The upside is that you may resell the equipment later on. Given that imported stuff is always double the price locally, you may even recoup all your spending. YMMV.Labspokane mentioned about Florida trips. That's what most of us do. If you have a friend in US, you can have your shoppings shipped to him/her and collect on a future trip.Anyway, welcome and good luck in your new life at Brasilia.One last comment: If you did not do already, check with the consulate if you can bring everything as personal belongings. The tax exemption for luggage is USD 500, but when you are moving in permanently, you may have a larger allowance for special items. Check the Migrante section of:http://www.receita.fazenda.gov.br/aduana/viajantes/ViajanteSituacaoEspecial.htm.(In portuguese, I could not find an english version)

author: Helder22
author_rank: Contributor
timestamp: October 02, 2014, 04:45:30 pm
content: No need to check. My wife works for Itamarati. Why do you think I move around do much lol.And I speak Portuguese. I'm brazilian!Valeu meu amigo!

author: David Hess
author_rank: Super Contributor
timestamp: October 02, 2014, 07:14:09 pm
content: Quote from: Helder22 on October 01, 2014, 02:06:33 pmI take it having a confederate that you trust outside of your destination who can forward items to you will not work?Another thing I would consider is reliability and serviceability. It might be worthwhile to double up on items which are critical and unserviceable in case one fails.

author: Helder22
author_rank: Contributor
timestamp: October 03, 2014, 01:18:25 am
content: I already am doubling up (or tripling up) on some things like multimeters, but a scope for example, is too expensive for me to have more than one of.And yes, I have plenty of friends in the U.S. who would send me anything I needed. Still would have to pay the shipping and duty though.But I think that I'm taking all of the major stuff already. I can always import the little things later when I need them.By the way, thanks for all the help guys!