I'm thinking about getting an oscilloscope as my next tool purchase but I don't really know what I should be looking for or what the options are. Ideally I'd prefer something that was stand alone, but I expect a device that hooks up to a PC for the display would be cheaper and offer more functionality. Right now my projects are reasonably simple but I'd prefer to buy a tool that I wont outgrow too quickly.
Thanks for all the answers so far, that's a lot of information to look at!
You don't mention exactly what work you do, but a good digital storage oscilloscope (DSO) will last you a while (and I guarantee it won't go out of date for a while). Sure, you can grab a secondhand Tektronix analog oscilloscope, but my storage scope has saved my frustration bacon more than once.
I have a Rigol DS1052E (a good review from a proper electronics engineer is here) which is a 50 MHz 1 GSa/s scope direct from the factory; they are about AU$675 on eBay. In my opinion, they are the best high-end hobbyist scopes on the market; considering what you get for the price I wouldn't trade mine for anything.
Since no-one has mentioned it yet, I'll post the link to the afrotechmods guide on purchasing an oscilloscope thinga-ma-jiggy.
http://www.afrotechmods.com/groovy/oscilloscope_tutorial/oscilloscope_tutorial.htm
first video on that page is the discussion about what kind you should buy etc.
I never had any luck finding a good used 'scope on eBay or Craigslist; there are tons out there, but they're typically missing probes or documentation. I ended up buying an MSO-19 from Link Instruments for about $250. It's a computer-based USB single-channel digital storage oscilloscope and 7-channel logic analyzer. It works well on Windows XP running in VMWare Fusion on my MacBook Pro running Snow Leopard. I have not found any USB-based 'scope with OS X-native software. I find the fact that it's a single-channel scope to be a limitation: it'd be really nice to compare a raw signal to one that's been processed in some way (through an RC filter or op-amp), but it's proven to be extremely useful.
Parallax has two oscilloscopes, the $250 PropScope, and $140 USB Oscilloscope. I don't have any experience with either of these. They do appear to both be 2-channel scopes, but neither seem to have any kind of logic analyzer.
Just get a used one on eBay. It's much cheaper than a PC scope. My family got me an old "Lizen" 20 MHz scope, which works well enough for what I do. I suspect it was under $50.
There's also this thing for $89, if it meets your requirements: http://www.seeedstudio.com/depot/micro-digital-storage-oscilloscopedso-nano-p-512.html
I have a BitScope, because I saw one for cheap on eBay, but I rarely use it.
Do you need the analog oscilloscope features, or are you planning to use it more for digital logic analysis? There are some decent PC-based logic analyzers that you can get for very cheap considering their capabilities, if you don't mind forgoing the ability to do analog signal analysis.
As far as actual analog-capable PC-based oscilloscopes, this is the only one I know of that has decent capabilities at a reasonable price: Link Instruments MSO-19. It actually combines 1 channel oscilloscope with an 8-bit digital logic analyzer, so you're getting a good set of features. Supposedly it can sample the oscilloscope at 2GHz, and the digital logic analyzer channels at 200MHz. It's mentioned by another poster above, for $250.
If you just want a digital logic analyzer, the best low priced one I've found is the Zeroplus Logic Cube LAP-C 16032 with a 32kbit/channel buffer, 16 digital channels, and can sample up to 100MHz, it's only $120.
Owon standalone oscilloscopes are pretty cheap (25MHz less than $200 if ordered from the manufacturer) and quite good for their price. http://www.owon.com.cn/eng/pdsSeries.asp
There's an article in the January edition of Elektor Magazine about building your own multi channel Logic Analyzer based on ATM18 board that they sell(?). This in turn is based on an earlier article about building your own Storage Oscilloscope using the same board. Depending on your requirements, either of these might be suitable as a stop gap until you settle on a final one.
You appear to have about a week to get to WHSmith's before the next issue comes out, alternatively you can pay about £1.10 to download the article about the Logic Analyser here or the Storage Oscilloscope here (you need to buy Elektor credits from the left hand menu). The board it's based on appears to be here.
I've got a dual trace PC based one made by Parallax. It has very limited capabilities because it's limited to the speed of the USB bus while taking samples. This makes it easy to use when you have a laptop or desktop PC handy, but also makes it useless when working on any higher speed signals. In all I only spent about a hundred $ on mine and it has served my prototype and hobby needs quite well. It just isn't any good for radio or microwave work.
Hey! I'm glad to have discovered a place like this. I am a beginning enthusiast, and was searching for the exact same thing--a decent little scope with a price I can handle. I too searched the eBay and Craigslist sites for hours. The scopes there all seem risky, since only one of hundreds of sellers offered a guarantee, and due to the (already mentioned) fact that many are offered incomplete. I found something GREAT tonight, though. There's a pro hobbyist selling "project" scopes for under $100 new! The site even offers FREE probes for those who purchase the fully assembled or kit versions. Info concerning the "DPScope" can be found here: http://www.pdamusician.com/dpscope/index.html The obvious compromise of this design is also its meager max bandwidth of 1.3Mhz. I'm new at this, too, so some of you experienced ones can check the spec's on the same site. One of my many books listed a 20-25Mhz maximum as the perfect starting point for a hobbyist, with two channels (dual-trace) as a must-have, and "storage" as a great help, but not a necessity. The said book is about two decades old, though! Happy hunting :--)
You need to clarify the difference between bandwidth and sample rate. For example, the PropScope is 25 million samples per second. It will barely be able to accurately digitize a 5 MHz square wave.
The Rigol is an awesome deal if you can get the hack going (see the mega thread on www.eevblog.com). I have a DS1102E that didn't need the hack, and it's a good scope.
The Link MSO19 you will outgrow very quickly. It has a single analog channel and cannot measure signals much below 50 mV
The best scope for me right now is the QA100 because it has logic analyzer built in. It has 100Msps sample rate, 25 MHz bandwidth, and 12 or 16 logic channels (can't remember). And $350. The Rigol scopes don't have any logic channels in the base unit. You can add them, but the scope price isn't very good anymore. In fact, it's outright expense.
http://www.quantasylum.com/content/Products/QA100.aspx
The QA100 also has protocol decoding. I can't imagine any engineer today not needing even a simple logic analyzer with protocol decoding at some point.
Consider a PC-based USB oscilloscopes from Pico Tech (UK). They are great scopes that have a really intuitive software and has all the functions of a much more expensive DSO. Very portable, most models fit in your hand! For example, their entry-level scope is a 100 Megasample/sec device that has all the electronics in the probe! They call it a "pen scope", and is priced at $200, but don't lets its simple looks deceive you! Since the PC software is the same for all devices, you get advanced triggers, waveform decoding for serial protocols, FFT, masks and whatnot, even with the entry level scope. You can even add custom/math channels to do advanced processing. All captured waveforms can be saved as files for later analysis/viewing.
Its clear that they have not limited/cut-down the features of their entry-level range, unlike most of the other manufacturers that make you pay more for "advanced" features which are really quite useful when you need them.
Most engineers recommended bench-top scopes, but I think they are old fashioned and reinvent features that can (lately) be done on the PC. This is their entry level series, of which I am already a super-satisfied customer. (I have the pen scope and another).
No complaints from my Rigol DS1102E. Feels like an Agilent I used to use in college, in a much smaller footprint. More info here if interested: Rigol DS1102E on Amazon for the 100MHz model, or you can get the 50MHz and mod it as mentioned above to save a little.
