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Cheap PC Oscilloscopes - Any Recommendations?
Missionary Man asks: "I'm an electronics teacher looking for a good (but reasonably cheap) PC based oscilloscope for classroom demonstration purposes. I've done a reasonable amount of research and come up with a few contenders. Ideally I'd like something with a bandwidth of up to 40MHz and 2 channels. Does anyone have any tales to tell regarding the use of any of these scopes (or any others I haven't found or mentioned) and can recommend a suitable device?"
"Here's the list of my findings so far:
- The DS2200C from USB Instruments will do 2 channels at 12 bit resolution, but only to 200KHz.
- The PCS100 from Velleman at QKits runs to 12MHz, but only 1 channel. It has a bigger brother, the PCS500, that has 2 channels and 50MHz bandwidth, but is a lot more expensive.
- Picotech do cheaper ones, like the ADC-40/42, but these only operate in the KHz ranges.
- Link Instruments sell the DSO-2102S that runs to 60MHz with 2 channels, but it's a bit out of my price range.
- Finally, I found the bitscope which seems to be just what I'm looking for, combining a 2 channel scope and an 8 channel logic analyzer for a reasonable price.
What does this mean?
I see them on case modding sites occasionally. As far as your use, I'm not sure how they would measure up. Knowing the thriftiness of many modders, you may be able to find a decent recommendation there.
Check this one out. . . I don't know the price because their price page is broken. . . It looks like everything you need in a PC Oscillioscope.
YOU'RE WINNER !
Another lame blog
I think my media player has an oscilloscope...
--Nick
Search google for bankruptcy auctions. I'm sure you can find what you're looking for. I work for a biotech that saved 75% of our initial budget by acquiring medical laboratory supplies from six other biotechs that went bankrupt in recent months. We did such a good job, our VC company gave us more than we asked for to buy the rest of what we needed.
The only thing necessary for Micro$oft to triumph is for a few good programmers to do nothing". North County Computers
Here's a good one, I think it's reasonably priced, too! :)
This is a little bit OT, but you can write off any purchases required for work, this includes education. Perhaps writing off that expensive oscilloscope would be equivalent to not writing off a less featured model.
Price page is here but it looks like it's around $900.
Here's the link to the price page
They cost a lot.
"Have you ever thought about just turning off the TV, sitting down with your kids, and hitting them?"
For cheap demo purposes, consider using the analog sound ports (line-in). I have had good success doing that for lower speed (44.1K).
I was looking for a PC based scope but couldn't find quite what I wanted.. I recently bought a used Tektronix 2215 for $50.
You can get to the price page by clicking the Shop link in the upper right. Looks like US $875.
I sometimes think back to my college days and really regret that I didn't focus more on the hardware side of computer engineering, primarily delving into the Computer Science land of algorithms and language design. In the last several years of my employment in the embedded space, I have come into contact with more hardware than you could shake a stick at, and without that grounding in hardware that I should have gotten in school I feel a little overwhelmed when faced with anything deeper than a block diagram.
I also wish that teachers like yourself didn't have to worry about providing materials like this within such a tight budget. It doesn't sound like this is just for this year's class, but something that can be used year after year. $300 for a material that can be used multiple times seems very cheap, especially considering the intrinsic value of the tool. Schools should be at liberty to spend what is necessary to bring the classes up to exceptional levels. Considering how the U.S. lags behind most other modern Western nations in Math and Science, such tight-fisting seems to be one significant factor in this drop off.
Good luck in finding the right tool.
I have been pwned because my
Two thoughts about your question:
- Do you really need 40MHz for educational purposes? Unless this is a device to be used in a college or higher education class , you can display sub-10KHz signals to teach a class how to use a scope.
- When I was at school, I learned how to use a real scope, with knobs and buttons and a not-so-perfect green screen, and I reckon it was way better to touch these dials and controls and have a direct feel for what they did on the screen than set some virtual thing and grab perfect-looking samples, to understand how things actually worked.
In short, any old regular scope that's well explained by the teacher is probably better than any interface+software setup that "isolate" the student from whatever electrical phenomenon he's trying to expose.
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
try this: http://www.softdsp.com/howtobuy.php
Some more info:s ds_more infos.htm
r oup/tan dm/news/31646
http://www.redacom.ch/messtechnik/softdsp/
This site lists the price as US $930.
http://www.techonline.com/community/tech_g
People that believe in their opinions don't post AC.
Here's the price page...
Remember that the oscilloscope bandwidth close to the frequency of the waveform being measured distorts that waveform. (In phase if the frequency being measured is a sine wave.) You need an oscilloscope bandwidth maybe 3 times the highest frequency being measured.
ICs often have very high potential bandwidths, and, when something goes wrong, even an audio IC can have sometimes have parasitic oscillations at extremely high frequencies. If you are working on a circuit, you need to be able to see those parasitic signals.
I don't like this fact, because it is expensive, but 100 MHz seems to be a good oscilloscope bandwidth. I bought a very old Tektronix scope to get the needed bandwidth at a reasonable price.
Comment removed based on user account deletion
OK, I know you asked about PC based scopes but if a plain old scope will do the job consider used.
A friend of mine bought a couple at a ham radio swap meet from a guy who buys surplus lots. IIRC they were dual-trace and something like 20MHz (he ended up getting one for me and for several other interested friends).
They were selling for ~$20 which means you could have a scope for every student in a class of 20 and still stay in your budget.
~~~~~~~
"You are not remembered for doing what is expected of you." - Atul Chitnis
I also have an Ozi-Fox handheld that has a PC and/or palm-based interface. It only does 20mhz and is single trace, but they are fairly inexpensive (< $90.00 USD) -- you could buy multiple units for classroom use. The display on the unit itself is not great, but works well for quick-and-dirty work.
Good luck -- m
Roving Web-Teleoperated Robot
After all, a DSO is "just" a D/A, and the input of sound cards is the same.
Maybe the sample rate on sound cards is not high enough, but the specs on some of the latest SoundBlaster (creative labs) cards are impressive (106dB...).
If you really need a good scope, you'll likely have to spend money. But if you are a hobbiest who just needs to see basic waveforms, maybe there is some good, cheap software out there that takes advantage of commodity soundcard hardware?
This issue is a bit more complicated than you think.
It seems people on slashdot are a bit overeager to buy PC based devices that can't be used as a standalone device. So far that I've seen, the benefits are mostly just cost, at the expense of portability, usability and quality.
I'd just find a real scope on surplus somewhere.
I just have a 'scope on "loan" from a local EE guy. Just an analog one. Effectively it is mostly a gift, but there are times he wants an analog scope so he wanted the understanding that he can get it back on occasion. For most uses, a digital one does fine.
It is not difficult to find a veritable mount of cheap oscilloscopes on eBay. You say you only need it for demonstration purposes, so why do you need something shiny and new? It can even be argued that the older analog oscilloscopes are better than newer digital ones. As always, resort to eBay if you need something not so good, and fairly cheap. Chances are you can find it there.
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I found their price list page through the google cache...seems like their stuff is out of his price range, but here's the link anyhow:
SoftDSP Price List
If a 2 channel audio frequency scope is all you need, then Oscilloscope 2.5 for Windows might do the trick. It uses the inputs on a standard sound card to grab 2 channels at up to 20 kHz. Disclaimer: I've not used it and a bit of Googling may find better alternatives.
Its slow, but is free (assuming you have the sound card).
Two wrongs don't make a right, but three lefts do.
What do you mean with "40 MHz"? 40 million samples per secord (MSPS) or signals with 40 MHz?
Did you know, that for displaying an 40MHz signal you need a DigiScope with at least(!) 400MSPS? If you go below, you can only display the frequency, but not the waveform (and for just measuring frequencies there are cheaper devices).
Markus
... can download free/open-source plotter emulation software at http://www.qsl.net/ke5fx/misc/7470.zip. This may be helpful to you if you buy an older scope from eBay. It will let you grab screenshots, overlay them, print them, and save them in several formats including their original HP/GL-2 plotter language. You can see some typical screen captures at http://www.qsl.net/ke5fx/synth.html.
I use a Tek 2430A on my own bench. These are great scopes -- you can get 150 MHz bandwidth for about $400-$600. A National Instruments GPIB adapter to interface it to the PC will set you back another $100.
I'm trying to add support for as many instruments as I can to this package. Any interested parties should feel free to email me...
Dahlmann tightly grips the knife, which he may have no idea how to use, and steps out into the plain.
If my understand is correct, some of the guys from the GNU Radio Project have developed a USB based software radio device that works with in linux. It is called the Universal Software Radio Peripheral. I think the first prototypes have shipped. The cost is pretty close to your price range. You can see it in action running an oscope program here. And of course it can be extended to do many more exciting things.
Since no one who's replied has answered your question, instead choosing to talk about unrelated things, I have to say that I'd go with the Bitscope.
Visit #electronics (our electronics+open source channel) on irc.freenode.net if you want to discuss.
I've had enough abrasive sigs. Kittens are cute and fuzzy.
The bitscope only has a 40MS/s data aquisition rate. Assuming that that's for both channels - 20MS/s each, then your left with a nyquist of 10Mhz. And you really need to oversample a waveform a lot more than x2 to see what it looks like. The analog bandwidth of the bitscope is high, but the A/D conversion will result in a lot of aliasing. That said. Its a really impressive unit for $400.00. I didn't think you could find something nearly that fast for under $700. Not exactly what you're looking for.
The software for a scope is pretty important - but without the raw A/D speed and resolution you won't get very far.
Yes, that was supposed to be a joke. That is probably one of the highest-end oscilloscope anywhere in the world.
It's funny. Laugh.
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Ya left one out. Write/go to any local company doing e-tech type manufacturing or engineering. Ask if they'll donate their old obsolete eqpt that they've already written off. I've never been in an engineering lab yet that didn't have at least one dinosaur in it.
Cloned foods give the statement "We had that last week!" a whole new meaning.
You'd think that somone could and would post a link.
DRMO = Defense Reutilization Marketing Office
This is the military agency that sells surplus equipment to the public. They usually have stuff like what you need.
If you can find something that has a HPIB/GPIB bus connector (IEEE-488) then you can connect it to a PC and use program your own interface (the libraries are very simple and very well documented). We did this both in the Army and also at a commercial satellite communications company (ours was to interface with HP spectrum analyzers thru IEEE-488).
Pedro
----
The Insomniac Coder
Happy memories of my 2340A, but I dunno if I ... they ran so hot, and their
would recommend spending cash to buy one on
the used market
mean-time-to-failure reflected it. We had a few
dozen under our control (research lab + class lab),
and there would always be a few with little yellow
Post-Its on them waiting to be sent out for repair.
Being a recient High school graduate, I think a schoool even haveing a program that teaches about electronics is an improvement. Hell my chemistry class was all books, they couldn't even afford to buy the chemicals! If this isn't bad enough we also have the highest school tax in the state!
softdsp.com
I bought one two years ago (around 800$ canadian)
it's pretty good, does 200 MHz / (5 GigaSamplesPerSecond equiv., whatever that means), two channel, USB.
The software isn't great. I don't think there is a linux port... I'm lazy, haven't checked recently.
The actual device is really sweet. If I haven't blown it up in two years, it is pretty solid! (I'm a chemist, and I do things like attach 400V power supplies to it randomly, I'll feel bad if it dies. Or me.)
Good luck!
If you google for "Cheap PC Oscilloscopes" with the quote marks included all you get is a link to this article.
I see even classic Slashdot is now pretty much unusable on dial up anymore.
If you really want to give your students a head start, I'd suggest finding any cheap scope with a GPIB interface and get an educational copy of the LabView software
http://www.ni.com/academic/edu_dsct.htm
(you should double check that the educational version actually supports GPIB because I don't recall if it does).
There's a hell of a lot of corporations out there that use LabView for all their test equipment, so there's a good chance your students will run into it when they get jobs.
Schools should be at liberty to spend what is necessary to bring the classes up to exceptional levels.
I have two words for you: lowest bidder.
Spoon not. Fork, or fork not. There is no spoon.
Many people make them, and they are real oscopes on
a PCI card... but the ones I have used were GaGe...
http://www.gage-applied.com/
Should not be too pricey, and I think they have
educational discounts. They are the best option
I have seen to get a real oscope in a computer, and
the sampling rate and digitization will beat a sound card hands down.
Personally you have to be careful about many of the "PC" based scopes that are out there. They usually suffer from bad analog bandwidth and short memory depth. Also you have to pay particular attention to many of the voltage/impendance limits of "PC" scopes.
Personally taking a trip down to your local electronics swap meet is not a bad idea if you have one nearby. Hear in SiValley there are a few around on the weekends where you get some older Tek/HP *cough* Agilent scopes for pennies on the dollar. Sometimes they need some work but most people are honest about it.
-Ho
This looks like a decent hardware version of what you wanted, they say it takes a bit of time to warm up, but you can't beat the price. Oh and hardware o-scopes rule, but cost a ton. There are lots of other o-scopes for sale on ebay. It's one of the few tech areas that seems to have some regular bargains, that and old workstations from anyone other than SGI, who has more sex appeal than apple.
Degaussing scares the bad magnetism out of the monitor and fills it with good karma.
Look at the prices for the PCS500 that you put the link with... it's $535 CDN, which is approx $411 USD... right in your price range!!!
If you are planning on using this setup for educational purposes try getting in touch with National Instruments. They may be able to get you set up with a data aquisition card and copy of their LabVIEW software.
I was a TA for junior and senoir level mechanical engineering laboratory courses at a major university where students used this type of system for many applications and a minimal cost to the univesity. The LabVIEW software makes it very easy to design your own "virtual instruments" as well.
Why do you need 40 MHz?
There isn't anything you can do at 40 MHz on an o-scope that you can't do at 2 MHz that won't be sufficient as a demo for the kids.
http://ask.slashdot.org/article.pl?sid=01/12/07/19 1220&mode=thread
ciao
I remember some years back that radio shack had a serial (DB-9 interface) probe with oscilloscope PC software - for about $100.
I don't think that this would have the range that you wanted, but I am sure that this would have it's place.
By the way, did anyone here have one ?
http://www.iamsam.com
I looked at the Bitscope web site, and they claim a bandwidth of 100MHz but they sample at a maximum of 40MS/s. This doesn't even make sense by the lower limit of Nyquist, where you need to sample at twice the frequency. In this case, the bandwidth would be only 20MHz. Am I missing something?
I don't know if you are considering used or not, but if you are...
l
SurplusShed is a site where I've bought optics from time to time, but they carry some electronics also.
To quote the website:
http://www.surplusshed.com/pages/item/r1456.htm
This is a powerful 100 Mhz oscilloscope with 5 channels and 12 traces. It has a four way trigger off either channels 1, 2, 3, or ALT. Trigger lock for stable automatic triggering for complex signals such as video waveforms. Can display several Lissajous patterns at the same time. 5 mV to 5 V per division (1 mV with magnifier) and 2% accuracy. Sweep speeds are 20 ns to 500 ms. This is the scope that is being used in production, testing, R&D, and home shops because of its versatility and portability. Tested and in good working condition. Complete manual copy included. Only have a few."
Oops, forgot to grab the price, but it is around US $225
Anti-gravity? That was *my* little secret! But I never patented it! Boy, was *that* dumb!
That's what a hacker do - take some existing tech and use it in new ways. If you can live within the frequency range of sound (up to 96khz, for most cards) a sound card is an excellent tool for signal analysis. Plus: there's already many tools and libraries out there for audio manipulation - Heck! you could probably even write the software for you needs in Python!
The Bitscope is an excellent choice. 100Mhz, net enabled, also has a built-in function generator, deep capture, logic analyzier. Very cool.
Hi,
/
You can try using Labview and one of their DAC cards. Labview comes with a bunch of oscilloscopes already pre-made, it will also do fourier transforms for you as well. I don't know the bandwidth off the top of my head, but I don't understand why you would need something with a huge bandwidth...
I've almost done an electrical engineering degree, and we've never had to use a scope to measure something that would exceed the normal bandwidth of an oscilloscope! Surely to teach electronics you wouldn't need something that big either. :
Labview is a powerful too in the right hands, and could be useful for many things beyond a simple oscilloscope!
I have no experience or contact with oscilloscopes, so would someone please inform me why they cost so damned much, even used (and up to friggin $20K, new!). Yeah, thanks.
The parent comment is exactly correct. You need 10 times the bandwidth if you want to see the waveform.
I said 3 times because, in my experience, that is the minimum at which I can extract any useful information. (Mostly you are looking for parasitic oscillations.)
I bought a DSO-2100 from Link Instruments and have been very pleased with it. Probably one of the best investments I've ever made.
I have an Optascope 81M USB scope from
http://www.optascope.com
I recommend it highly. Nice software and really works well for me. Also only $189.00!
Specs are:
1 Ms/S Maximum Sample Rate (500Ks/s 2 channels)
200 KHz Bandwidth
20Vpp Max Input for CH1 & CH2
8 Bit Vertical Resolution
2 Channel
External Trigger Source
Trigger on Rising or Falling Edge at Any Voltage
Variable Trigger Voltage on DSO channels
10%, 50% and 90% Horizontal Trigger Position
Auto or Normal trigger modes
USB interface
If the signals are relatively low use your sound card!
44khz 16 bit precision.
This was covered a few years ago; no surprise that most people forgot. The answers are mostly the same; still a good read though: http://ask.slashdot.org/article.pl?sid=01/12/07/19 1220&mode=thread
-----
Trogdor the Burninator!
You can get a new Tektronix 1002 (two channels, 60 MHz) scope for $995 without any educational discount. If I were in the market for a scope, I'd try to find one of those used. They're small, reliable, and inexpensive for their abilities. $400 is a probably low, but I wouldn't be too surprised to find one for $600. To me, learning to use the controls on a standard scope is worth quite a bit. (An extra $200? You be the judge.)
Good point. I know my last client was a wireless equipment manufacturer and when they went from 900MHz for 802.11 to 2.4 Ghz for 802.11b their old equipment was worthless because it mostly topped out at 1GHz. The old equipment was sold off to employees but they probably would have been just as happy to give it to an educational institution if they had been asked.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
Cthugha, baby!
Check out the HandyScope 3
http://www.tiepie.nl/
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item =2597976348&category=45005&sspagename=STRK%3AMEBBI %3AIT&rd=1
Tectronix 2245A 100 Mhz, dual chan.
It's a good scope.
I'm sure there's deals to be had on used Tektronix "Lunchbox LCD" scopes (the TDS3000 series), especially now that the enhanced TDS3000b series is out.
My 4-channel, 100MHz TDS-3014 cost me about $4k back in 2000 when they were the latest and greatest... seems like the 2 channel version was about $2500 then. You could probably find a used TDS-3012 for about your price range.
--Rob
There are a quite a few used Tektronix 465 scopes going for about $200. Check newsgroups, eBay and go to some Hamfests.
Wansu, th' chinese sailor
The most common source for these type of PC-card "instruments" is National Instruments.
If you are teaching about electronics, you would be better off buying a used Tek 475 (or similar) analog scope, you can get a very good one for $300-400. They can learn about the actual circutry, timing, measurement error, etc. without
getting heavily into sampling theory and digitial
signal processing.
If you want the students to learn "the new way" of
electronic instruments, check with National Instruments about used/traded in cards, and software; they may have an educational discount.
There are also some "poor man's" type of scopes made of surplus parts, old TV's, etc.. that you can find in the back pages of Nuts& volts magazine; I don't recommend these if you want the students to learn what they will use in the future, in real-world engineering applications.
Finally, there are mixed-mode instruments that are analog with analog storage, analog with digital storage, analog with digital readouts added, various standard instruments with serial or GPIB interfaces, and s/w from the mfr or 3d party for
control and analysis.
See if you can find on some engineer's shelf a catalog/book from Tek or HP, say, from the 1980s
or 90's, this is about the vintage that will work and be in your price range.
If you were considering PC-based scopes just to get the cost down, perhaps you might consider an actual used oscilloscope. There are many used ones for sale on eBay, and there appear to be some that would more than fit your criteria. For example, this one.
Try here for $25 for 4 chan stripchart
http://www.dataq.com/
Check out the PCI/PXI/AT/USB/PCMCIA-5102 from National Instruments. I think they're about $1200 or so and 20 MHz 2-channel 8-bit, a little more than you wanted to pay but it's good stuff.
Sounds like your kinda thing. Although I personally
am allergic to the name HC Protec because the first
scope I bought was theirs and it started to fall
apart about a year after we bought it.
For serious work, Tek or Agilent are still what
I would buy. For two days a year teaching duty,
the above will do.
they have a inexpensive 200$ pc based scope. Uses USB 2.0.
designed mostly for learning.
Modern circuits are not so well controlled as someone might guess. To have 20 kHz output with little phase distortion, it is necessary to pass more than 200 kHz.
But that's not the issue. ICs allow the design of circuits with bandwidths that are literally physically impossible with discrete components. The fundamental bandwidth limitations of the transistors used in the IC may be 200 MHz or more, or even 1.5 gigahertz. Any small problem can cause a circuit to oscillate at 50 MHz, even if the IC is supposedly limited to far less than this.
All you need for oscillation is gain and some positive feedback. In the real world, circuits try all possible combinations almost instantaneously, and begin oscillating for reasons the designer never foresaw. For example, maybe there is capacitive coupling through the IC packaging, and the output circuit alone is oscillating.
This is only a slight exaggeration: There are 4 steps toward making a new electronic device: 1) Build the circuit. 2) Supply power for the first time. 3) Apply an oscilloscope probe and begin discovering all the reasons the circuit is oscillating when it shouldn't. 4) Then discover all the other reasons the circuit isn't working correctly, if any.
I was never a person who thought that killing people and destroying their property was a good way to resolve social problems, but at one time it was my job to repair the automatic flight control systems of fighter-interceptors in the U.S. Air Force's Air Defense Command.
These aircraft required 250 hours of maintenance per hour of flight. (Aircraft meant to be sold to other nations, also, required 15 hours of maintenance per hour of flight. I've followed the development of weapons systems ever since, and my opinion of what is actually delivered is that it is often fraud, or close to fraud. United States taxpayers: Your assigned duty is to find the money to pay, and to avoid thinking.)
Anyhow, during training flights it was required to pull several g's. Sometimes at high accelerations the electronics would go completely crazy, and all inertial reference would be lost. The only fix for this at the time was to land, regain stability, and take off again. The aircraft that had this problem were therefore not much use for any situation actually requiring defense. Worse, the problem seemed to have nothing to do with any particular aircraft, but seemed random.
One day while trying to make a faulty system work on my bench test mockup, I discovered the reason. Some of the amplifiers that controlled the gyros had high frequency parasitic oscillations at perhaps 100 times the normal frequency of operation. You couldn't see the oscillations with normal equipment because the frequency was too high. I had borrowed an oscilloscope from some co-workers who worked on faster electronics.
The design of the amplifiers was acceptable, but many of the amplifiers had bad solder joints. Those with bad solder joints would oscillate; oscillating amplifiers would amplify at the required low frequency, but had a much smaller dynamic range than amplifiers that were not oscillating. (Yes, that bad solder joints could cause this doesn't make much logical sense, but most parasitic oscillations don't make much logical sense.)
The amplifiers had other defects that caused them to have a high failure rate. Every time an amplifier was pulled from an aircraft for a conventional repair, an amplifier was drawn from stock and put in the waiting aircraft so that the aircraft would be immediately operational. That was the reason the instability problems kept moving from aircraft to aircraft.
I drew a circuit diagram of my test setup, wrote an article about the problem, had a photographer take photos of the test setup, took screen photos of the parasitic oscillations, and sent everything to those who review such things. This had several effects. Someone at Air Defense Command headquarters wrote a letter praising my work. When everyone was reviewed for p
Depending on what you're trying to teach, an analog 'scope might be a fine way to go. However, if I could have only one 'scope to teach with it would be digital. ie. I think you're right to want a pc based 'scope.
Digitize a waveform - bring it into Matlab or Scilab or even Excel (ok OpenOffice). Apply an FFT. Look at all the neat frequencies. Analyze the output of a modem - 'Holy trellis Batman' or "Gee look at the nice constellation" for QAM.
With an analog 'scope you are stuck in the boring old time domain.
You kids and your fancy new transistorized scopes'
My 1968 Tek 453 took ~two hours to warm up, and when a tube died we had to walk twenty miles in the snow just to get a new one!
So modulate in hardware and demod to baseband in software.
With a simple analog multipler (for example, the Analog Devices AD834) and e.g. a 5 KHz oscillator, you can AM a band-limited (say, DC-500 Hz) signal, put it in your sound card, then do the demod in software (another multiplication will work).
This will cost you, in total, about $5 (you can get free samples of the AD834 and you'll need some resistors, some caps, a couple op-amps, and some wire) and will give you DC-500Hz through your modulator or 20Hz-24KHz without it. Not too shabby, especially compared with $500.
By the way, if you're going to spend $500ish anyway, why not pick up a Tektronix 2445 or 2465 on EBay? The 2465 has 350MHz bandwidth and is, IMHO, one of the nicest all-around scopes out there.
You might want to check out the boards put out by Interface, a Japanese company. Specifically, their PAZ-3161 board supports up to 40 MHz sampling rate (one channel; 20 MHz if you sample both channels). Not only does this company make excellent boards (my lab has several), they provide both Windows and Linux drivers for the boards.
I've done some preliminary work on writing signal-analyzer software for their PCI-3525 board, which I would be happy to share (it's not close to being fully-functional yet, but we've got a student who may be using these boards, so that might change soon). I'm also happy to try to adapt this code to more general use. With these boards and existing code, your task might be much easier than you originally thought. Also, their sales engineers are very willing to help solve problems. I don't know the prices on their boards (ours were donated), but they are excellent devices.
On stereophonic equipment, the monaural sound obtained through multiple channels will enhance your listening pleasure.
That's a great story. I wish I had some mod points left. I think that hearing things like that makes me almost wish I had gone into ee instead of cs. On the other hand, considering my worse-than-usual grades in my analog electronics class, maybe it wasn't such a bad idea to go into software. :-)
Did you mount a military-grade, variable-focus MASER on an unlicensed artificial intelligence?
In my day we used to build our own from old television sets. We called them silly scopes (kids).
You have to make a few adjustments if you do this. but save the big capacitors, I hear you can use 'em to train your pets. (Anyone know how many farads one should use on a medium sized dog that won't stop barking?)
I also own their K8016 function generator. The two were made to work together (for Bode plots, among other things) and I find that they work quite well. The only trouble I had was noise on the scope due to an inadequate power supply. It was rated 9V @ 1A, but actually dropped to 7V at that current. The scope draws 1A easily. I built a better PSU for it and now it is fine.
For that money, you can maybe do better but the Vellemans fit my needs nicely.
Russ W. Knize
Between $875 and $950. I fiddled around with the URL and found the page. http://www.softdsp.com/howtobuy.php
Well, the bitscope and similar ilk should do fine for a teacher's (canned) demo/dog & pony role, but thay have some real limitations that must be considered.
First, is the limited range of input signals for the analog inputs, and how rugged the inputs are. Can you safely input a large signal without damage? Can you control the bandwidth of signals/triggers to provide stable/good displays? Another is the rate of screen refresh under dynamic/live conditions.
Troubleshooting can turn into a big time-eater as you struggle to figure out what's wrong. Is it broken? Miss-wired? Settings wrong?
These are areas where basic analog 'scopes along the lines of Tektronix 223x family really shine. eBay is your friend! A Tek 2236A is an excellent model, I have one and love it. If you must have digital capture, then a 2230/2232 will probably do fine, and can be found for not too much more.
Regardless of the chosen gear, probes are another part of the system to consider.
Keep in mind that a good set of probes can be a substantial investment if the equipment doesn't come with any. There is no better probes than Tek in my experience. It's those little things like the tip clips and miscellaneous goodies that take the hassle out of probing signals. Tek probes/accessories are very expensive ($100+ for basic probe kit), but they excel.
All of the cheap after-market probes I've used are horrid in the probe goodies department.
Oh, don't knock the bazillion knob & button 'scopes. I find them far easier to use than the soft key/menu based gear. Just reach over and push/twist the desired control. Instant response and direct feedback as you adjust the controls to see what you want.
For durability, don't knock that old lab gear. It's built like a tank and can take a lot of use/abuse.
You won't have to worry too much about the kids playing around and blowing the gear up if they are given the chance to explore for themselves.
You ARE going to be a GOOD teacher and let the kids explore on their own with some hands-on experience once in a while, aren't you?
Otherwise, you might as well buy an "educational" video and sit in the back cleaning your nails while the tape plays and the kids throw spit-wads between isles.
"I agree with the parent post about a sound card being a nice classroom demonstration scope. For higher mhz, you can pick up a real scope from Ebay for much cheaper than a PC card solution."
I think this is the better solution IMHO. Plus a lot of Oscopes can be hooked to a computer for processing of the output, and control.
You could have your students build a fairly good PC based O-Scope with eight 5-Mhz sample-and-hold A/D converters, a 40Mhz clock, a small bank of SRAM, and some glue logic to blast all the data back to the PC. Maybe get together with the Computer Science professors, and have their students write the PC software. Then your school would only have to shell out for the parts, and the project itself would teach your students a lot about how real-world design works. Tech
NI has some great PC based scopes for a range of prices. Check them out at ni.com
Do you have a source for your sig? A google search only turns up your posts on /.
Since there is obviously not a single well known place for selling electronic test equipment, does anyone know where the most popular place for buying and selling would be? (Not necessarily for finding the cheapest ones.) I have several older power supplies, dmms, etc., but I haven't sold them because I do not think I would be able to get much on Ebay or anywhere else I know of where people would actually look for them.
Any ideas?
Does anyone know of a good PC oscilloscope with Mac support?
(since we're already talking about PC oscilloscopes)
Sounds to me like the question is from a high school teacher. I seriously doubt spending any more on a scope would be worthwhile, since I'd bet it's primarily going to be used to show students wavy lines, or maybe as a glorified multimeter (he's only buying one, so it's not like the students will be using it regularly). I wish the poster gave a few examples of the types of projects his class works on.
That said, I wish schools would stop blowing their entire budgets on computer labs. I hate to see a school paying for a computer that isn't at least two years old when the money could be going to text books that aren't twenty years old and falling apart.
It would be really nice to see high school electronics courses teaching students how to properly work a scope, but you'd need enough for an entire class. It's amazing how many engineering students get 2 years into a computer/electrical engineering program and don't know how to use a scope to read important parameters from a circuit.
For high bandwidth it needs to react quickly. But that is hard to get without self-induced oscillations.
For high sensitivity it needs large amplification. But that is hard to get without amplifying noise as well.
It needs both accuracy and precision. Indeed most scopes are calibrated against a precision standard that is tracable back to the Federal Government's standards reference (the so called "tracable certificate of NIST calibration")
Remember that an oscilloscope needs to be much more accurate than anything it's used to design/test. Best analogy: Would you want somebody grinding eyeglass lenses for you to have 20/20 vision or somebody with cateracts?
--Rob
Gameboy oscilloscope
If you have a $300-400 budget, you should look into buying a real oscilloscope and scrap the PC based idea. Outpost has a 30MHz scope with dual channel inputs for $369.
If you need a digital scope (unlikely for what you described doing), then the cost rises sharply.
For the amount of money you're specifying, you can easily pick up a much better built and far more versatile O-scope in the form of an older Tektronix instrument.
In fact, that price range will easily get you a 475 or 475A, good to 200 or 250MHz, respectively. It will also put you well within reach of a nice Tektronix 7000 series benchtop 'scope, like a 7704 or even a 7904.
No matter what you may hear, the PC was never designed to be an O-scope, and no amount of external hardware, I believe, will ever turn it into anything that can compare, in terms of value for the $$ and quality of construction, with early Tektronix hardware.
I believe it's also EXTREMELY important to teach would-be technicians and engineers that the PC is not the be-all and end-all of test gear. Never has been, never will be. Oh, it can be useful as an instrument CONTROLLER in automated test setups, yes, but it was never intended to replace the functionality of actual made-for-purpose test equipment.
Give your students a real education. Get a real oscilloscope.
Bruce Lane, KC7GR,
Blue Feather Technologies
Try looking at some Acqiris digitizers. I like these better than the National Instruments and the Gage scopes.
http://www.softdsp.com/howtobuy.php &
http://www.softdsp.com/sds200_download.php
They even do not check their web as the link is still local!!
Yes, theoretically, a rise time of 1/5 that of the fastest signal. However, usually at the upper bandwidth limit, there is phase distortion and amplitude reduction. So, it seems to me that the rule of thumb might hold true. I seem to remember that some fast rise times are achieved by providing resonance near the upper bandwidth limit, or some other synthetic method, so that there is overshoot. I don't remember much about this. It that possibly an explanation for the different estimates?
That's why I'm glad that my school only offers an Electrical Engineering with Computer Option major. Basically, we focus most of our time on hardware design, then our last two years we split off and focus more on either digital or analog, and possibly expand our programming knowledge. It's really a good program, and as much as I hate the amount of work I have to put in it, I love the things I am learning.
You've probably stopped reading by now, but just in case...
I use a PCS500 and am very pleased with it. Whilst people have made good points about the relative value of analogue scopes, don't underestimate the usefulness of it being PC-based. The single shot digital storage capability combined with easy printout is really nice to have. The data logger facility is likely to be useful too. I use mine primarily for working on valve audio amps, so I'm a big fan of the true RMS measurement and FFT mode.
On the downside: it's a shame they don't include a pair of probes in the box, and it would be nice if they updated the design to use USB instead of the parallel port. Also, with the timebase set for low frequencies, it can take an annoyingly long time to refresh the display. I suspect if fills a large buffer with measurements before updating the image, and at low sample rates that means long delays. Switching to data logger mode is often the easiest solution as this updates the display incrementally.
Regards,
James.
No doubt about it, analog scopes are great in most situations (even superior). However, in some situations a digital storage scope can be extremely helpful. Standalone digital scopes tend to be very expensive. So, if storage is an important feature to the poster, then PC based scopes might actually be the best option. If storage isn't that big of a deal, then analog would probably be a better option.
----
All of whose base are belong to the what-now?
Get a standalone digital scope on ebay. I got a 400 MHz HP (Agilent) for about $450. They have cheaper digital scopes for cheaper.
This is nice and cheap, dunno if it'd be good enough for you.
I found several serious software bugs. I can't remember them all now. It has an AC voltmeter function, the spec page claims 1% accuracy. It worked ok up to about 10KHz and above that the reading were completly wrong. The hardware is just a fast ADC so the PC software did the task of adding up the area of the voltage versus time graph.
A picotech support person reproduced the problems I found and promised to send a new version of the software. Months later after a few reminders they finally emailed me some software, the same buggy software I'd already been supplied with the unit.
I have seen portable LCD dual channel oscope with 1G sample/s for less than $900. So it might be the 'price' is unreachable.
Maybe the thought of using a GameBoy for anything serious tickles your funny bone but I followed the link. It is quite serious and useful.
Our high school physics lab had at least an oscilliscope between three people (classes of 20), and they were used intermittantly from age 14 up to teach basic concepts.
What about the optascope? This unit has open specs,open source support, and a reasonable price.
www.optascope.com
I've never used one, but it looks like a good option. (for lower bandwidth applications)
Thank you, good story! Makes me remember why I read /.
TINA is a circuit analysis program, and TINALab II is a superb PC-based lab with oscilloscope, multimeter, etc. functionality. They work together like charm, but can be used separately as well. www.tina.com
here
Just wondering, if the purpose is just a cheap O-scope, or if it being PC-based is the point. If all that is needed is a cheap, high-quality O-scope, I'd check Fair Radio Sales, http://www.fairradio.com/oscill.htm
// 30pF. Frequency response: 0Hz to 50MHz (+/- 3dB). Max. input voltage : 100V (AC + DC). Input coupling: DC, AC and GND. Supply voltage: 9-10Vdc / 1000mA. Includes: PCS500 unit, 2 test leads, PC parallel cable, practical manual, CD with software. #PCS500, New, $497.00
They have an awesome selection of surplus electronics and test equipment. The URL I listed has listed on that page, a Tektronix 7603N11S Checked, for $400 USD. If PC-based is what you have to have, down the same page:
PCS500 is a digital storage oscilloscope that uses a computer to display waveforms. All standard oscilloscope functions are available through the supplied Windows program. All normal oscilloscope funtions can be selected with the mouse. Optically isolated connections are made through the computers parallel port. The oscilloscope and transient recorder have two independent channels with a sampling frequency up to 1GHz. Any waveform displayed on the screen can be stored for later use. Timebase: 20ns to 100ms per division. trigger source: CH1, CH2, EXT or free run. sampling frequency - real-time: 1.25KHz to 50MHz, repetitive: 1GHz. Spectrum analyzer frequency range: 0...1.2KHz to 25MHz. Transient recorder: time scale: 20ms/div to 2000s/div. max. recording time: 9.4hours/screen. 2 channels, 1 external trigger input. Input impedance: 1Mohm
Granted, it's Windows-based, but there it is. I love Fair Radio..great people, super deals..learned of them from my Amateur Radio days.
Progressivism (aka US 'Liberalism'): Ideas so good they need a police/surveillance-state to enforce.
But for the price you want, even a good DSP based data logger from National Instruments may prove elusive. But if you're skilled with MatLAB IEEE488.1 HPIB or GBIB card control library, you may be able to find an older but decent scope with the ports (this is old school technology, beware of the time costs...).
Personally, I never mix digital logic with analog problems, although there are notable exceptions like those new mixed systems-on-a-chip
A nice project perhaps would use rtLinux or the rtLAB live CD to do the "Real Time" data capture from a 12bit high speed PCI data capture card from National Instruments. Should be able to do the system's bus speed with two low res. channels (any RTLinux C philanthropists out there that could write a GUI ?)
Note this too, most current A/D converters generally use a ramp/trigger or V to F converter model that limits bit-depth at higher frequencies. I think there are other options...
Votes for a GNU style open hardware Scope? I'm interested...
I came across Dynon Instruments the other day. They seem to have a solid product (although it's not available yet). It's got a scope, an arbitrary waveform generator, a programmable power supply and a few other things. Looks interesting...
You're completely missing the point, which is that he used the phrase "tight-fisting" [giggle giggle].
national.com - a/d eval borad comes with wave vision java based gui
ADC08200EVAL $249.00 Out Of Stock ADC08200 Evaluation Board
http://www.national.com/appinfo/adc/files/12D04
Don't reinvent the wheel, its already patented
What should be installed in a laptop that physics teacher carries around? well, almost anything could be simulated by a program. For example radio receiver. Fractal creation.
Any free package to start?
John's comment (Tek 2400 series):= 98603&cid= 8413630
http://ask.slashdot.org/comments.pl?sid
If you need to digitize it (GPIB), do it AFTER the scope has captured it.
gewg_
A new pc-based scope with these functions, at US$495:
u res.html
- Digital Storage Oscilloscope (DSO) 2-channels 80Msamples/sec
- Logic Analyzer (LA) 16-channels
- Arbitrary Waveform Generator (AWG)
- User Programmable Power Supply (UPPS) +/- 10V
- Programmable Clock Output (1kHz - 150MHz)
http://www.dynoninstruments.com/docs/elab-080feat
9/11 Eyewitnesses to Explosive WTC Demolition 1 of 2
Yeah, but these are retail pricing. If you're using the scopes for the classroom (and especially if you're purchasing them with a school PO), they should be willing to give you a really nice discount. Back when 1GB drives (the full-height 5.25inch 1Gig drives) were around $3,000, we were regularly getting them at 1/3 the retail price. That sort of discount would put this thing in the requestor's price range.
Death and taxes may be inevitable, but even those can sometimes be negotiated.
Free Software: Like love, it grows best when given away.
Heh. I'm in high school, and I'm taking my third semester of electronics courses (digital, microprocessor [wiring Motorola 6802's from scratch -- classy], and audio); everyone has a scope at their workstation, and using them to analyze and debug our circuits is fundamental to the course. It's a great class.
Hi, Cliff. I saw your request for suggestions on low-cost PC o'scopes for classroom instruction. I'd suggest you check out the following link. It's not for a PC o'scope per se, but for a complete lab set for teaching electronics and RF for a small class that includes demo circuit boards, multimeters, and yes, even a PC o'scope. The whole kit is available from the American Radio Relay League as part of their Education and Technology Program. I'm not positive, but I believe the kits are free to qualifying schools. The kit was designed to supplement a curriculum available free to anyone. http://www.arrl.org/news/stories/2004/02/12/3/?nc= 1
Try this link:
http://www.aplab.com/tmi/3660d.htm
This isn't a PC based scope; its a 60 MHZ DSO that I bought for the equivalent of $380 little less than a year back during an inventory clearance sale. I've used it extensively during field trips, and have found the unit to be extremely rugged. Doesn't offer as many features as Tek or other better known brands, but for the price its worth buying. Comes with an optional "Ultrascope" software package for importing the waveforms onto your PC and doing some analysis.
Heh. Actually, you kinda sound like a 10 year old yourself; either that or you're just *really* immature for your age. Oh, and CHRIST probably doesn't read /., so stop complaining to Him here.
That is amazing. I took the first circuits class when I was trying to get a minor in EE (Major was Comp Sci) and we had a lab portion where we used scopes right away. I don't see how you could be learning anything in EE without touching a scope for 2 years. You did say just 'Engineering', perhaps you were talking about the Civil Engineers.
I did the same stuff in highschool, very cool. It should be standard highschool stuff, it will serve you well. It's surprising how few schools have qualified teachers who can create the programs and teach the material.
My school didn't specialize in technology though... it was just big enough to keep a strange instructor and support the program. After the instructor retired, the course disappeared.
nt
A witty saying proves you are wittier than the next guy.
Missionary Man,
If you're looking for something specifically for the classroom, there is this great device sold by JDR that appears to come with a set of integrated labs for students to do. It is NSF (Nat'l Sci. Foundation) sponsored, and you may get a discount if you become a beta college/university partner.
http://mission-technology.com/
Hope this helps!