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Ask Slashdot: PC-Based Oscilloscopes On a Microbudget?
New submitter fffdddooo (3692429) writes I know it's something that people used to ask every few years, but answers get old so quickly. I'm an electronics teacher, and I'm wondering if it's possible to find some oscilloscope (and why not spectrum analyser?) for recommending to my students, to be able to work at home. I'm thinking of something near $50-$70. Two or three years ago, I'm sure the answer was No, but nowadays?
The same reader points out two options spotted on Amazon: one that's "very cheap but Khz" (it's also a kit that requires assembly), and another that aims to be capable of 20MHz, 2-channel operation. What's out there, he'd like to know, that's not junk?
This is one pocket scope for less than $100
This is another.
My local Craigslist has 9 oscilloscopes listed between $50 and $150.
Yes, but "oscilloscope" != "logic analyzer". And the Logic 16 (I have one) is 5x the OP's stated price range.
I kinda feel like the OP asked where he could find a cheap, sporty little car, and you're telling him he should consider buying a fire truck.
This is something I was actually in the market for at one point and had researched as thoroughly as I could a few years back. The bad news as I discovered it was that anything that's cheap is junk, and anything that's not junk is not cheap. Although this was, as I said, a few years ago now, and it's possible that other alternatives have arisen since then.
One of the best things I found at the time which was modestly inexpensive was some hardware that plugged into an iPad or iPhone. The one that I found was a device called iMSO, and it has a bandwidth in the neighborhood of a few Mhz, which isn't too shabby for an analog oscilloscope that cost under $300.
File under 'M' for 'Manic ranting'
They have ethernet and USB - amazon.com
Also, ask these questions on eevblog forums. Slashdot is not great at hardware.
small review/discussion
ie., over half of the nitwits posting so far are recommending logic analyzers. Please stop. There are also cheap JTAG programming solutions, power supplies, etc. Don't start recommending wrenches when someone asks you for a screwdriver.
I have been using the Analog Discovery for an embedded systems class I recently completed. The regular price is $239 but the student edition is only $99. It’s small enough to fit in your pocket, but powerful enough to replace a stack of lab equipment. It is driven by the free WaveForms software and lets you build and test analog and digital circuits in virtually any environment, in or out of the lab. Here is the link:
http://www.digilentinc.com/Pro...
2-Channel Oscilloscope
2-Channel Waveform Generator
16-Channel Logic Analyzer
16-Channel Digital Pattern Generator
±5VDC Power Supplies
Spectrum Analyzer
Network Analyzer
Voltmeter
Digital I/O
Now supported by MATLAB / MATLAB student edition.
If you are an electronics teacher, you should know better. The PC-based scopes and the various "DSO Nano" clones are universally crap and none fits into your budget anyway.
Your students would be vastly better served by buying a used analog scope, those could be obtained on eBay and similar places for a song these days. A used Tektronix or Hameg scope will beat the pants off of any PC-based toy and, more importantly, the student will actually learn and understand how the instrument works and what is being measured, because there are no "magic buttons" to push.
If the student has a bit larger budget, then the Rigol DS1052E or the newer DS1074Z is a really hard to beat value. There are also Siglents or Attens for the budget conscious, but both brands tend to suffer from poor manufacturing quality and the price is not really much lower than the Rigols.
Forget spectrum analyzer - there is no decent one for less than $1000 on the market. Digital scopes can do FFT, that helps in a pinch, otherwise the student can always record the data from something like the Rigols above and do a proper spectrum analysis on the PC, e.g. using Matlab or some other tool.
50-70$ will give your students a good if not excellent used analog scope such as suggested from numerous members in here
Other than eBay, less obvious sources for getting a scope on the cheap would be your local HAM (radio amateur) club, there is always one in your city, look them up (they're really friendly and love new faces). Another way to get some cheap scopes, is to visit the various electronics repairshops, service dept. etc. Ask nicely, perhaps bring a free pizza to the overworked technicians, and who knows? Maybe you'll end up with a Scope for the price of a decent pizza slice. (I KID YOU NOT, I've heard friends of mine who have done this, and even gotten a free Spectrum Analyzer, albeit old...but working).
Yet another source is the various tech-schools out there, they have old surplus equipment too, one of my friends also got a serious stash of scopes from them, perfectly legal. You could even look up military surplus sales, they often sell truckloads of much better stuff, some people make a killing buying pallets of Scopes, analyzers, bench multimeters, solder stations and much more from the military auctions, and re-sell them for seriously high prices on eBay.
A few things you may want to know about old scopes though, is that they are FRAGILE. Scopes around 20mhz are useful for low-end digital experiments and standard old audio & CCTV repair and experimentation (enough to teach you!) A 100 mhz scope throws you into the digital era, you don't need much more than that. When you find one (beggars can't be choosers, but if you pay a little...) then you may want to check that all the knobs are okay (yes, you can lube them yourself, but check for broken plastic bits, if it breaks - stay away), Good strong CRT (no hefty burn-ins or weak display), also look for the famous LOST TRACE (this means loose parts inside, again...stay away unless you know what you're doing).
A couple of good scope probes can be as expensive as the instrument itself, you may actually want to purchase those from China, they're okay...and cheap. Test leads are the only thing I recommend people to purchase new, because they take the most beating.
What this world is coming to - is for you and me to decide.