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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?
http://xoscope.sourceforge.net...
Needs a or many sound card.
Have fun!
I can't call that English
http://www.instructables.com/t...
Take your pick.
An enigma, wrapped in a riddle, shrouded in bacon and cheese
We've been using the Saleae Logic 16 - https://www.saleae.com/logic16 at work.It goes from 2 channels at 100MHz up to 16 channels at 12.5MHz. We use them for debugging all the low speed stuff (serial ports, I2C, SD, etc.) - basically everything but the CPU memory interface.
Their upcoming "pro" version adds analog sampling, but it is not yet out.
This is one pocket scope for less than $100
This is another.
Here's one. http://www.instructables.com/i... There is more stuff in the comments, such as https://github.com/hitchcme/Gi... Don't know if they would fit your requirements, but something to look at.
As long as we're talking about cheap PC-based oscilloscopes, let's talk about the other important kind of cheap PC-based test equipment, the digital logic analyzer, such as this one.
Not everybody needs one of those old HP/Agilent behemoths (you know, the ones that ran Windows 2000), and in my experience they can be a pain in the ass to use, too. (Not to mention how damn heavy and huge their are.)
#naabhaprzrag, #sverubfr-000, #agi-fcbafberq, negvpyr[pynff*=' negvpyr-ary-'] { qvfcynl: abar !vzcbegnag; }
I own one of these. It will run you about $120 dollars not exactly making your price point but there are some cheaper options this guy makes. Check out: http://www.gabotronics.com/oscilloscopes
My local Craigslist has 9 oscilloscopes listed between $50 and $150.
Try the analog discovery from diligent(????)
Its 99$ for students, 2 channel 14 bit, 100 mhz sample speed, front end is less than this, 100 mhz 2 channel waveform generator and 16 channel digital stuff.
The buffers are 8k or less, but it seems to work okay...
If you are willing to bump your price range to around $150 (or $250 for the more advnaced) you could use http://www.bitscope.com/BitScope.
Check out their store http://my.bitscope.com/store/
Both are a bit above your price range. But the PicoScope 2200 is a nice entry level scope. Alternatively some assembly required with OpenADC.
bitscope --- get one!
That a pretty tough price range but the xminilab kit from atmel is a neat little setup.
but the analog bandwidth is only 200k if your willing to spend as much as 150 you can get the xminilab-b with Up to 2mhz plus signal generator and spectrum analyzer
what the fuck does the lack of a quality $50 oscilloscope have to do with "truth"?
you're right in a round-about way; "China and Walmart" got everyone used to paying almost nothing for a bunch of shiny shit, so when you actually have to pay $$ for something useful or quality it feels like an outrage for no directly-relevant reason.
"They were pure niggers." – Noam Chomsky
Take a look at http://www.digilentinc.com/Pro... $99 Student pricing
Not exactly what was asked for, since it only plots the output of Android device sensors, but the price is peanuts: SensorScope: https://play.google.com/store/...
I ask as if you can get away with a sound card based O-Scope that's a cheap way, and, you can also find software for spectrum analyzer use as well. Quite possibly, repurpose old PC hardware laying around the school, any laptop will do and would do nicely.
This could be combined with a auto shop for car audio stuff so now you have a blending of science with a hobby/fascination that is very common to high school students.
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.
National Instruments recently released their myRIO devices for education. http://sine.ni.com/nips/cds/view/p/lang/en/nid/211694 . They include 10 analog inputs (up to 500 ks/s aggregate), 6 analog outputs, and 40 digital IO. The myRIO's can also be used for FPGA programming, LabVIEW programming, etc... Also see http://www.ni.com/white-paper/14621/en/ .
*Edit - typo.... (damn, I noticed it as soon as I hit "submit") The iMSO cost *around* $300, not less...
File under 'M' for 'Manic ranting'
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.
When recommending test equipment, I tell them the same thing that I tell those needing a PC and ask for recommendations. I ask what are your requirements, and what are your wishlist.
Start with the essentials. Do you need Microsoft Office, why? Do you need to keep in a budget? If so how much and why? Can you spend extra for extras? If you can get the extra from an alternate for less, would it meet your requirements?
The PC scope. Define your requirements. Budget is item one listed. This severly limits your options. Is above audio REQUIRED? If not some simple audio interfaces can be used. On Linux there is an oscope program that works great with a sound card. Back to requirements, are you taking absolute voltage measurements? Do you require DC coupling? If so this is not an option that meets your requirements.
If working in audio frequencies, there are some excellent free spectrum analizers for free in Linux and not sure what is the options in Windows or Mac. For Linear Frequency and Log amplitude the JAAA program in most linux repositories whorks great. For Log frequency and Log amplitude, the companion JAPA program works great. I use it to ring monitors for band/PA. Audacity does a great job creating waveforms. I use it to create frequency sweeps for sound setup with the JAPA program. The sweep generation is a little obscure. Under Generate tab, it is the Chirp function. Set start frequency, end frequency, start amplitude and end amplitude, liner or log sweep, and duration of the "Chirp" to generate your signal.
For those with a good soundcard or external audio interface the generated sound is direct digital so any noise is not in the recording, but in the analog stream after the digital. Be sure to set the project frequency high, such as 96KHZ, in Audacity to prevent ailising in the upper frequencies. This is a better signal source than any CD recorded sweep due to the higher sample frequency than 44.1K of CD.
To recap, due to budget, shop for what is free or low cost. Your interface to the outside world will be your expense. There are low cost or no cost software that can enable better capture hardware. The above while nice did not meet the stated budget requirement. Retails for $299. So is the wishlist able to justify the higher cost?
The truth shall set you free!
Be aware that you plan to use a sound card in a way it was never intended to be used. So if you hope for anything beyond 10 MHz, you are probably out of luck. And at that range, you already get "real" oscilloscopes for about 100 bucks.
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
http://www.fpga4fun.com/Hands-...
I have a Hantek 6022BE and I'm please with it, but my needs were modest, just show a few waveforms to the kids at school
Nullius in verba
http://www.raspberrypi.org/bitscope-micro/
This seemed like something that while passed your price has oodles of potential for all kinds of teaching uses.
Look at Ebay, in some cases you may be lucky to find what you are looking for there. Don't hesitate to look at items from Agilent or Rhode&Schwartz.
Otherwise go for the reasonably priced items at sites like Conrad.
If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.
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.
Digilent's Analog Discovery is a good option if you can get the $99 student pricing.
2 Channels scope, 100 Msps, 2 channel function generator, 16 digital logic channels, 2 external triggers.
Software comes with a sdk.
"For every complex problem, there is a solution that is simple, neat, and wrong." - H.L. Mencken
Nobody needs to learn to drive any more. We can teleconference everywhere. If you need your body to be somewhere, just rent a taxi! It's all virtual these days.
As usual, there are cheaper gadgets you can buy if you are a student. Let me do some slashvertisement here. It is a little bit outside the budget, but it does something more than just oscilloscope:
www.digilentinc.com/analogdiscovery/
* Two channel oscilloscope, up to 5MHz bandwidth
* Two channel arbitrary function generator
* Stereo audio amplifier
* 16 channel digital logic analyzer, up to 100Msample/sec
* 16 channel pattern generator
Etc etc
The series of Seeed oscilloscopes are a bit clunky, but otherwise reasonable.
50-70$ 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.
Tim / fffdddooo (3692429), Not unlike the Digilent Analog Discovery product (2 channels, 5MHz analog BW), the Embedded Artists Labtool offers 2 channels @ 6MHz analog BW and a AWS generator. The cost is $139USD or $99EU. The URL is: http://www.embeddedartists.com... and it's available from distributors like Mouser.com I think Digilent is ahead with delivered courseware. I'm a community college professor at stcc.edu and I'm looking at the same ideas. One of the milestones for our beginner student is getting the whole time-domain mentality across to them (think ... DuMont Oscillagraph :-) ). Despite my dinosaur upbringing with big Tek 515's and 535's, I think our students could use these PC-peripheral style instruments with no loss of meaning.
In actual practice I think we could accomplish our goals with a 200KHz 'scope just as well. As I'm sure you're already aware, most frequency domain discussion nowadays can be effected using FFT software + a digital sampling oscilloscope. Obviously any truly RF stuff is going to require something beyond these low-cost instruments but, for around the same price as a textbook, they can have a scope and signal generator as a takeaway.
Best Wishes,
Coop
Hack A Day has a few options for DIY and sourcing used scopes. http://hackaday.com/?s=oscillo...
It all starts at 0
Here's a product review of a handful of small, inexpensive oscilloscopes. http://www.jameco.com/Jameco/w... They look kind of handy compared to my ancient HP.
Anyone know of any good rugged oscilloscopes for e.g. use out in the field? Meeting area classification a bonus.
A number of labs like SLAC have a salvage department that collects old, but sometimes still functional equipment. If you are associated with an educational institution you might be able to get some of this stuff for free. It will be old but probably fine for some types or student experiments .
Smartscope, US$ 199, open source USB oscilloscope / logic analyzer / arbitrary waveform generator (and optionally Xilinx Spartan 6 FPGA dev kit) was recently kickstarted, it is expected to ship by August 1st. Supports Linux, Windows XP/7/8 (PC version), Mac OS, Android & (jailbroken) iOS.
Anyway, also buy a cheap 2nd hand analog oscilloscope (under $50), you will learn a lot from that.
Nothing is purely digital when it comes to actual hardware, it's just really fast analog.
If you're not too worried about the source having enough power to ruin anything, the hardware can consist of a resistor, a variable resistor (volume knob) and two wires. Just be sure to turn the knob all the way down to 1M ohm before connecting to an unknown source. Then slowly turn it up until you see a sufficient signal.
Check out the circuit-gear units. The new "mini" is just $99 http://www.syscompdesign.com/C... I have the previous generation unit. I've enjoyed it for just hacking around, and it's great for demos, since the computer it's hooked up to can be projected. The GUI software for it is open-source, so that's neat.
And the AC Electronic Snobs are out in full force.
Better yet, forget all that stuff and teach them to arrange clothing at a store like Abercrombie or to make a coffee at Starbuck's, because that's where all the jobs in the future will be: retail.
The price of scopes goes up rapidly with bandwidth. 20MHz is cheap. 100MHz is more expensive. 1GHz and up is very expensive. Tektronix sells a 33GHz scope starting at $30K. That's the first question you have to ask. For kids doing Arduino-level elecronics, 20MHz is fine. None of the I/O goes faster than that. (If you want to look at Ethernet or digital video signals, you need far more bandwith, more than you can afford. Fortunately, today that stuff mostly works.
(Back in the 1990s, I was trying to build a LIDAR unit for a robot. The parts aren't expensive. The problem is that, when it didn't work right, I needed a high-bandwidth scope I didn't have to find out why.)
I wanted to scope a signal that required about 1Mhz of resolution, but do it for $2 using a sound card that only goes to 20Khz. The $2 solution was a much slower crystal for the circuit under test.
Somewhat surprised no one has mentioned Xprotolab yet.
http://www.gabotronics.com/dev...
8 channel logic analyzer at 2MSPS (3.3V)
2 channel analog at 2MSPS, 200kHz analog bandwidth, -14 to +20V inputs
Small OLED display
1.6" x 1"
As an extra bonus prize, arbitrary waveform generator!!
$49
Never tried one personally-- tempted but I think my Tek would get jealous.
Be sure to get one supported by the excellent opensource sigrok library
The DSO Nano from Seeed Studio almost fits that bill. The specs aren't amazing, but at $89 with its own screen it's useful for education or light tasks. I keep one in my bag for emergency troubleshooting in the field.
They have a more capable version, too, for anyone who's interested.
If you want a vision of the future, imagine a youtube comments section scrolling - forever.
Instead of a spectrum analyzer, you can use an RTL-SDR dongle as described here. Sure it has a lot of limitations, but it only costs you 10$, and with the scanner software you can get a very wide bandwidth.
"It's too bad that stupidity isn't painful." - Anton LaVey
Dave from eevblog he does a lot of reviews of this type of hardware
http://www.eevblog.com/2010/05...
or check this search to see a lot of reviews of specific ones old and new
https://www.youtube.com/user/E...
no i'm not affiliated with EEVblog its not click bait its just the best reference material i know to help this in his decision
tl;dr
buy a used analog one they're often cheap or free
I have a DPScope and rather like it.
It's not a super advanced scope, and doesn't compare to standalone scopes like the Rigol DS1052E, but for someone on a budget who has fairly basic needs, it's worth a shot. It was developed by a guy who was annoyed at the drawbacks of other PC-based oscilloscopes and their software.
I use mine for testing homebuilt electronics, and it does well for that. I wouldn't use it for anything significantly more than that sort of stuff, though.
If you are a windows user, Christian Zeitnitz offers a PC based Soundcard Oscilloscope free for non-commercial use. It also has a frequency spectrum waterfall diagram, x-y plots. Easy to install and run. Fun to speak into your microphone to test it out.
Only suitable audio speed signals like XOScope. I.e., 20-20000Hz from 44.1kHz sampling and 16-bit resolution. And without external hardware voltage dividers/protection the usual warnings about blowing up your soundcard if you feed in voltage outside of ±0.7V into it.
From their website:
"Baudline is a time-frequency browser designed for scientific visualization of the spectral domain. Signal analysis is performed by Fourier, correlation, and raster transforms that create colorful spectrograms with vibrant detail. Conduct test and measurement experiments with the built in function generator, or play back audio files with a multitude of effects and filters. The baudline signal analyzer combines fast digital signal processing, versatile high speed displays, and continuous capture tools for hunting down and studying elusive signal characteristics."
I have used it also as an oscilloscope (waveform wiindow). Runs on linux and osx.
Official website.
Research universities have tons of old junk that they would love to get rid of for very little cost.
A used Tektronix or Hameg scope will beat the pants off of any PC-based toy
Looking on eBay, a s/h HAMEG will start at 5 times the budget specified in the original question. Even more once shipping charges are added. So while you may be correct: that a "proper" 'scope will beat one of the PC scopes, your solution fails due to completely missing the price constraints.
And if you want to provision equipment for a whole class of students, finding s/h gear piecemeal on the internet is not a practical solution, since it doesn't scale beyond one or two "lucky" buyers.
politicians are like babies' nappies: they should both be changed regularly and for the same reasons
Here's a 100 mega samples per sec digital scope that can be built for $92.70. It's based on a floating point gate array.
http://www.fpga4fun.com/Hands-...
The parts for it can be purchased here.
http://www.knjn.com/
I know this might be out of your budget but have you looked at the MSO-19? http://linkinstruments.com/mso... I designed this as the training tool for my high school FIRST Tech Challenge team the Landroids. They used it to develop various custom Arduino & AtTiny based sensor array for their award winning robots http://youtu.be/zRwOx2D7WCw . I packed enough features in the scope so the students can tackle FPGA based projects when the need arises. It was selected by NASA as the only oscilloscope on the ISS. And the best part is that it is designed and manufactured in NJ/PA to demonstrate that affordable manufacturing can still exist in the USA.
There's this new thing called "Ebay"
http://www.ebay.com/sch/i.html...
In all seriousness though, for what you are looking for they are about $70
I went with a used bench-top model myself because the analog display looks cool and I don't really need all the features. I'm just a hobbyist and not in need of what your students will be doing.
Ive a lot of time for the usbee - analog and logic analysis and basic decoding of serial protocols too. I also love the fact it can do long term signal capture / recording too. Yes you can buy chinese knock offs but really, have some decency and support small companies making Cool Shit.
For my own money i have an old cathode tek and an old lcd 60mhz tekscope that i bought on fleabay thats damn handy. Also keep an eye out for cheap old fluke scopemeters too...
Emerson Electric provide CT Scope for free. For years. Just register to download it.
http://www.emersonindustrial.com/en-en/controltechniques/products/software/commissioning/ctscope/Pages/default.aspx
Good Luck.
You think this distinction is relevant to 99.9% of what the OP wants to do? Or what most people want to do?
You gonna bust out the 100GHz sampling scope to look at a 555 because you want to measure neutrinos?
You're nuts.
A scope is vast overkill for most hobby-level electronics today. We are on the shoulders of giants, why are you worried about shoes?
They have a new product for under 150.
http://www.bitscope.com/produc...
But I've been very happy with my Bitscope 10 + assortment of probes (if you can spring for that). Does everything, s/w is a bit 00's (features), but rock solid and has an API for writing your own software. If you can spring the extra 150, you can just get a real scope+analyzer vs high latency toy. Have used them on both Windows and Linux, no issues.
I haven't tried this yet but it sounds promising for low level debugging.
http://www.picaxe.com/Hardware/Add-on-Modules/PCB-scope/
Bitscope Micro - USB , 40MS/s, USD95 in quantities of 10 or more.
Fairly decent set of software tools for it (including a basic FFT spectrum analyser and a protocol decoder that can do UART / SPI / Canbus.) Software runs on windows/linux and Raspberry Pi - You can download the software and tinker with a few bitscopes that are online to get a feel for it.
Specs here
You are in a twisty maze of processor lines, all alike.
There is a lot of hype here.
Check out xprotolab (http://www.gabotronics.com/development-boards/xmega-xprotolab.htm) from Gabotronics. Not too fast or too easy to use but it is very capable and Gabo provides very good support. It is self-contained (small oled screen) but can also send info to PC over USB.
Also, the "arduino" teensy 3.1 could be used to make a USB-based scope for ca. $20 (plus some additional parts) and can have a lot of other cool uses too. Check it out: http://www.pjrc.com/teensy/tee... and http://forum.pjrc.com/threads/....
Troll AC is fail. Logic analyzer's whole job is to show SPECIFIC waveforms. The wave being square doesn't change this.
In other words...
You know nothing, AC.
You need to look around more.
$300 gets you a quite usable Chinese dual input DSO with true 1gs.
Things have come a long way..
OOOOO so snobbish of you, Sir Hipster. The guy asked for the best cheap ass car and you told him to fuck off and buy a Ferrari. DSO Nanos work fine, especially for a student.
He's correct:
20 MHz oscilloscope at AliExpress, $61.99 delivered. USB, use a computer for the display.
60 MHz oscilloscope at AliExpress, $308.00 delivered. Complete with display.
China has improved.
Try a Rigol.
Back in what has to qualify as the computer stone age, a high school Biology teacher I worked with got a bunch of A/D converters and wired them to his networked C-64s, I wrote the software myself. We were measuring the acceleration of gravity (okay, not a Biology experiment, but he saw it in a magazine and wanted to try it himself) and graphing student's heartbeats and so on - in 1986. So really, the oscilloscope part is trivial. Might even be able to use the existing A/D and DSP from the sound card, if you can figure out how to feed your signal to the Mic. input. (Yes, 1986 - the school board wanted him to upgrade to PC XTs, he preferred to use what he had. When they saw what we did with those old C-64s, all they could do was scratch their heads.)
Perhaps I should have mentioned that at the time I was looking for an analog oscilloscope.
File under 'M' for 'Manic ranting'
It is all junk. Having mounted a serious attempt to design and build an oscilloscope, I realized I was not saving a ton of money by doing it myself, even assuming my time is free. The majority of the cost of modern oscilloscopes is, surprise! the hardware. They're selling enough that the relatively small margin they do make pays for R&D (though I would assume that phase amounted to copying some reference designs...).
Well, except for software lockouts. Fuck software lockouts.
as others have said, soundcard-based scopes would be the simplest and easiest (if the work you'll be doing will fall within the bandwidth)
A set of probes will help - this set has some protection circuitry built in: http://www.virtins.com/P601PC-...
For extra insurance, use a cheap USB sound-card instead of the line-in on your laptop... much easier to replace the USB one when (not if) you blow the input.
I use this in my classes — the myDAQ from National Instruments (DAQ=digital acquisition).
It's USB plug-and-play, with a few basics like oscilloscope (200 kS/s, 16-bit), DSA (digital signal analyzer), signal generator, and Bode analyzer built-in, through use of it's "ELVISmx Instrument Launcher." Better yet is that it comes with a non-expiring copy of LabView.
It has:
* DMM ports (digital multimeter)
* 8 digital I/O
* A/D audio I/O, +/-2 V
* A/D I/O, +/- 10V
* Power supply +/- 15 V
* Counter
Cost it $180, for example through www.studica.com.
If you are a student and working in the analog range, there are some great software audio RTA spectrum analizers out there. With an aftermarket analog interface, 16 bit stereo 96KHZ sample rates are supported for low quanitization error and allising at the high end.
My super cheap interface cost me $15, supports 16 bit stereo for wide dynamic range (lower noise floor by far over my internal sound card) and 44.1 or 48KHZ sample rates. With free Audacity to generate sweep tones, and JAPA RTA software, I can sweep filters, phase lock loop filters, speakers, rooms, etc for well within budget. With cheap, but up to spec sound interfaces, they can be used for student and semi pro work.
Not a slashvertisement, but the innexpensive interface I am using is one of the Behringer U-Control series. With Audacity as my function generator for Sine, Triangle, Square, or sawtooth, I can sweep linear or log over any reasonable audio frequency range I need. With JAPA on Linux patched with Jack, and input from the interface, I have over 100 DB of dynamic range on most frequencies in the 20-20K range. Any cheap 8 bit scope card simply does not have the resolution for this. Use what works best, even if it is cheaper.
The truth shall set you free!
http://expeyes.in/ is what you are looking. Very very powerful and cheap. Compleate open source hardware and software design.
I simulate your mom on my dick every night
Low-frequency solutions are no substitute for what an actual oscilloscope can do, but when you're trying to learn electronics, being able to see what the circuit is doing at all is far better than just guessing what it is doing. Multimeters have a use despite their 1 Hz sample rate, and a measly 20 kHz sample rate is going to be much more useful than that.
That said, just as soon as you can replace them with anything else, you'll decide that sound cards suck.
My present favorite solution is to use an FT245RL (a $5 USB chip that implements a simple parallel FIFO buffer, with drivers for Linux and FreeBSD already in your kernel) along with an AT89S52 (a $1 re-programmable microcontroller with 32 I/O pins, though I usually end up dedicating 15 of them to the programming interface and communication with the FT245RL, leaving only 17 for general-purpose use) and just write little programs for the microcontroller to read/write whatever data I want and transfer it to/from the PC. I even built my own programmer for the AT89S52 using the same two chips and a Perl script. (Naturally, the AT89S52 used in the programmer was programmed via other means -- I used a parallel port.) This generally allows me to do anything digital that I want to do. (Obviously my wants aren't that great.)
For analog, I attach a MCP3301 ($3 12-bit ADC w/ SPI interface) to the FT245RL & AT89S52 combo, which allows reading everything from DC up to 100 kS/s. At $3 a chip, adding multiple channels is inexpensive as well, and I've used up to eight simultaneously, driving them all with the same control signals and just reading the resulting eight data bits in parallel. While this is barely better than audio frequencies, the major advantages are that there is no DC filtering, and that you actually know what input voltages correspond to the values you read from the ADC. Sound cards are really only meant to record frequencies and relative amplitudes.
Of course, at this point you're up to about $25 to $50 depending on how much stuff you had to buy and how much stuff you already had, and you've invested a hell of a lot of your time. Time is quite valuable. Spend enough of it and you might as well have picked up a second job and just earned the money to buy that oscilloscope. ...but if you are a student, putting these chips together is kind of something you should be learning how to do. The big time-waster for me was the software, as I wrote an assembler, a script to drive the programmer, software to run in the microcontrollers, and any software needed on the PC to record and display data.
So a sound card is a rather attractive solution to people who don't already have an oscilloscope and can't justify the expense of one. The needed components are minimal, and the software already exists. Sure, sound cards can't measure DC, but you probably have a multimeter that can, and anything not DC, like a 0.1 Hz square wave, is still going to be visible as little spikes which at least lets you know something is going on, which is better than not knowing. Only very low frequency sine waves aren't going to be visible at all, but they're not that common, and in fact are rather hard to generate.
I think this is the best bet. One can get a REAL oscilloscope that's used for a very reasonable price. Sure, it may have a floppy drive instead of thumb drive for exporting images, or no export at all, but for student use and demonstrations that should be fine. I'd check ebay too, or a local electronics warehouse type store.
The best option for students needing cheap and versatile measuring equipment. would be the Red Pitaya.
I have found that the Red Pitaya analog side is a bit weak. The digital side makes for an interesting platform, but IMO the whole package does not achieve the instrument-grade quality I had hoped. Significant spurs and wandering sample rates mean you can really only expect to use it at very low frequencies (think 100 kHz, max). A nice soundcard can be made to do the same thing for a far lower cost.
https://itunes.apple.com/nl/app/spectrumview/id472662922?mt=8
Take a look at the sigrok project. We have rather a lot of experience with low cost lab gear.
For a long time the best option for a standalone scope has been the Das Oszi scopes, sold under the brand names Hantek, Protek and Voltcraft. As a bonus, a guy name tinhead has reverse engineered the schematics. Hopefully we'll have it supported in sigrok very soon.
There's also the SmartScope for ~$180.
Quite a bit over the OP's budget at $189 but perhaps worth a mention, nice little thingy with open source software:
http://www.syscompdesign.com/CircuitGear_p_8.html
oh, and apparently a mini for $99:
http://www.syscompdesign.com/CircuitGear-Mini_p_29.html
For ~$199 with the oscilloscope front end, I like the DSLogic because it has a very deep on-board buffer - 32 MiB - which is actually critical in a cheap USB 2.0 device.
This is because, when the USB 2.0 spec added 480Mbit/s Hi-Speed, they upped the speed from 12 Mbit/s and forgot to also require usb root hubs to add DMA within the PC to take the data away.
And so whatever your OS is, it'll just never reliably handle keeping the data moving. The existing USB fifo chips that support HiSpeed have woefully underequiped buffers to maintain flow should the PC "go to lunch" for more than a few 10's of microseconds.
This is why Hi Speed is 48MiB/s on paper, and usually only reliably sustains maybe 20 MB/s. The saleae suffers particularly from this - it's only got 2kB of buffer, guess how long that lasts?
Good USB 2.0 HiSpeed devices will have at least 8MiB of addition buffer to cover for the ~millisec gaps the PC OS will add. This means at least an FPGA plus a DRAM chip - exactly what the DSLogic has.
Most cheap USB 2.0 oscilloscopes omit the extra buffer, and consequently keep dropping out: The saleae will give and error message saying "sorry, but it appears your PC can't keep up with this sample rate". They are right, it is actually the PC's fault - but only because in order to get back to the USB transfer within the ~30 us window is a bit optimistic, unless the whole OS is written with that in mind as the firstmost priority, and getting even rtlinux to do this is actually near impossible - the jitter is usually closer to 100 us.
USB 3.0 doesn't have this problem, (it has DMA!) but all the devices that support it will probably be above your price range - nearest I can think of is the BladeRF, but it only supports from 27 MHz to 6 GHz, and it's really aimed at SDR more so than reliable oscilloscope capture.
(Forget cheap SDR "digital tv" dongles: they only really do ~ 10 MB/s over USB 2.0, and they very often drop packets. The radio coding for digital tv simply allows for the occasional data loss that results, so they mostly work for their intended purpose anyway.)
Forget anything firewire - it has DMA, but it's protocol, while efficient, is far too complicated, and cheap chips that can talk it just don't exist, even for the "slower" old 400 Mbps standard.
You may also want to try the Lab-Nation SmartScope, at $179, but it's only got 2MiB of buffer. The plus for it is that it has really good iOS/Android integration, but that short buffer will limit you.
There's also a new 10 GHz BW oscilloscope on there which is just starting up - but it doesn't appear to have any buffer at all, instead requiring many partial captures of a repetitive signal to form a clear picture. This may be ok, depending on what you're doing, but it's no good for capturing real world "once off" signals. Ok for debugging really high speed serial links though.
If slow sample rates (~100kHz) are useful, check out Xprotolab's handhelds!
Pretty much, yeah. What do you want me to say? Market-driven universities churn out the EE grads like industrial cookies on a conveyor belt.
What market, you ask? The government loan market of course.
http://www.gabotronics.com/development-boards/xmega-xprotolab.htm
If you dig around on their site, you can see they have multiple variations. All inexpensive. All pretty full featured.
How expensive does a decent-to-good quality 'scope need to be? In other words, what's in there and what sort of price tag can you expect for even just the bag of parts and why? Taking this further, how about an open source design, with various construction options according to local part availability?
OP might be interested in this Kickstarter from a short time ago:
https://www.kickstarter.com/projects/dreamsourcelab/dslogic-multifunction-instruments-for-everyone
Here is a link to an instrument (CGR-101) that I purchased a few years ago. The equipment is manufactured in Toronto. http://www.syscompdesign.com/I... The software is open source and can be used with Linux, Windows or Mac. I have found this product to be extremely useful and versatile. All of the required components will fit in a laptop case.
I've seen a lot of old, but still very good, analog scopes sold on eBay for a tiny fraction of what a new modern scope with the same specs would cost.
They might be heavy and hot, but they are very repairable if they ever break.
I'd be surprised if you couldn't find a nice 40 MHz scope for $50 to $100 (depending on extra's and cosmetic state) or a really nice 100 MHz Tectronics with several add-ons for about $250.
I used this Oscilloscope based on an Arduino and ATMega328 running with a 16MHz crystal. It's more of a toy/demo scope, not even great for audio frequencies and for lower scales you probably want to add an instrumentation amp front end. The thing I like about it is that it reuses/upcycles all of those pocket NTSC (or PAL) analog TVs obsoleted by the FCC a couple of years ago.
I generally recommend against USB test instruments because of their shortcomings but for a USB based oscilloscope, I would at least get one which supports network analysis which may be particularly useful for students:
http://www.syscompdesign.com/C...
http://www.syscompdesign.com/C...