Hi everyone.
First of all, I just opend this new topic asking about oscilloscopes because all of the previous ones i've found are too old, is this ok?
Well, here I go. I'm looking for an oscilloscope. A cheap one but reliable enough, I mean, kind of a compromise between these two things. I'm not profesional and i want it to do my own homemade stuff. I did a search in ebay and Amazon and i found those two models (Hantek PC Based USB Digital Oscilloscope 6022BE and Mini DSO201 ARM Osciloscopio Oscilloscope Digital 2.8 ") What do you think about them? Are they trustworthy?
On the other hand I found a link right in this forum http://www.picotech.com/applications/oscilloscope_tutorial.html
that explains to you some criteria you have to take into account to choose an oscilloscope.
I want it to meassure a constant sine wave that (at least) theoretically does not change neither in time nor it's amplitude. I want to try several frecuencies (1MHz to 20MHZ at the most and probably also frecuencies in the range of Khz). And never more than one input signal at the same time.
I don't know if all of these things i just told are enough or not for you, but as i said in previuos posts, I'm a newone in this and i'm stil learning ;)
Otherwise if you have a second hand to sell or a spear one or knows a site where i can find cheap ones, everything will be welcome.
Thanks!!
Could you ask the Physics teacher at your local school if you could bring your project in to test on one of their oscilloscopes?
There are plenty of secondhand 100mhz scopes on Ebay. They might be borderline. You could buy one and sell it if it is not up to scratch.
For 80 dollars the Hantek will be about your best bet at this point. It even comes with probes, it seems! Of course you need to supply your own PC....
I don't have experience with that particular model but a friend recently gave me a Link 2102m DSO that is very nearly equivalent to the Hantek... and it cost 700 dollars when it was new in 1997. It works well and has nice software, but needed a parallel port to work. I have an old IBM ThinkPad 600e, with Win98, so that is perfect for me.
Your Hantek is USB and has a LabView version bundled with it.... nice.
Yes, you do need two channels at least, even if you think you don't at this time. A single-channel oscilloscope is like a single shoe. Sure, you can wear it and it will protect your foot. But walking any distance will be an utter pain in the butt.
There is nothing wrong with "old" scopes. If you had, say, four hundred dollars or more to spend on scope, an "old" analog scope for that money would be a far better instrument than a new 400 dollar digital scope. For under 100 dollars budget and a low bandwidth requirement, then go for the Hantek.
I got my Tecktronics 2013 from ebay a few years ago for $100.00. I had to buy new probes but it has all the manuals and works very well. I think it was a good deal.
Bill
Hi Paul-R. Your idea of asking about using the one from my local school is good, but I'd rather having my own oscilloscope so if I break something or set something else on fire ::) it will be just my own properties ;)
Yeah if i'm able to find a second hand one i'll be great.
Thanks
The teacher might take an interest and turn it into a school project. (You could mention the Bedini SG saga).
Also, sometimes they can have scopes which are VERY good. If there are several, you could get a very useful idea of what you need and what you want.
Thanks for your advise TinselKoala. If i don't find a better choice I'll go for the Hankel. I think i have to confirm if the manuals are with it befoer i buy as well as checking the minumun pc specs required. (and of course, probes too). An good old model sounds like a good option, but I don't know anything about them so if I find something that seems like a good choice I'll ask you guys before.
One last thing. Can you explain that thing about the two channels? Why do I need tow of them? (as i just said i dont know so much about it)
Thanks!!
Quote from: Paul-R on September 30, 2013, 10:32:21 AM
The teacher might take an interest and turn it into a school project. (You could mention the Bedini SG saga).
Also, sometimes they can have scopes which are VERY good. If there are several, you could get a very useful idea of what you need and what you want.
PAul R. Your idea sounds good. That could be a whole experiment project for students. I'll think about it.
Thanks!
Quote from: watari on September 30, 2013, 10:36:34 AM
One last thing. Can you explain that thing about the two channels? Why do I need two of them?
I think TK will suggest that you are likely to be wanting to compare two different points in your circuit at exactly the same time.
If you have a slow running project, like a pulsed motor, there is a software scope called Winscope where the probe plugs into your sound card. It is free.
Quote from: Paul-R on September 30, 2013, 10:49:52 AM
I think TK will suggest that you are likely to be wanting to compare two different points in your circuit at exactly the same time.
If you have a slow running project, like a pulsed motor, there is a software scope called Winscope where the probe plugs into your sound card. It is free.
What I want to do is to built a Hartley oscillator circuit, and I want to check if the real frecuecy of this circuit matches with the thorical one already calculated. It something very simple compare with most of the things I can find in forums abut electronics. So Will I need to channels for that anyway? I guested he meant to compare the signal of my circuit with a given "control" signal. Am I wrong?
Quote from: watari on September 30, 2013, 11:02:39 AM
What I want to do is to built a Hartley oscillator circuit, and I want to check if the real frecuecy of this circuit matches with the thorical one already calculated. It something very simple compare with most of the things I can find in forums abut electronics. So Will I need to channels for that anyway? I guested he meant to compare the signal of my circuit with a given "control" signal. Am I wrong?
Yes, for your one specific project you may just need to display a single waveform. And I frequently only need to look at a single waveform myself. I can also get to the store just fine by skipping down the block on one foot!
A scope is a major investment. Money, time, benchspace, learning to use it. And it is the "king" of test equipment. You will encounter many many cases when you want to see the effect of one signal (like a pulse generator output) on another signal (like the response of a RCL tank circuit) or you need to look at two output values like voltage and current simultaneously to determine a power curve. You will find two channels useful in your simple Hartley oscillator work as well. So don't even think about getting a single-channel scope as your primary instrument. It will be hard to find a decent single-channel scope anyway! (I have one, the Tektronix RM503..... it's a classic antique, a precision _low frequency_ oscilloscope that I use mostly for displaying Lissajous patterns in x-y mode).
Another issue is bandwidth. Your scope should have a bandwidth that is comfortably higher than the base frequency of the signals you will be measuring. The reason for this is so that you will see transients and proper waveshapes for signals other than sinusoidal, as they contain higher-frequency components. So if you intend to measure, say, signals in the 5 MHz range you probably need a 20 MHz scope for good accuracy.
The Hantek scope you posted at first will probably fill all your needs for some time, and at the price, under 100 dollars, it isn't too much to risk.
I am sure it comes with all the manuals you will need, and in fact you can download the manual here:
http://www.electronicaestudio.com/docs/Hantek6022BE_Manual.pdf (http://www.electronicaestudio.com/docs/Hantek6022BE_Manual.pdf)
The ad says it comes with probes and the software including a LabView version. The manual says you need Windows XP/Win7. I've had a look at the manual, it seems clear and complete.
I can't think of a reason why you shouldn't get the Hantek. I haven't seen any customer reviews, but Hantek is a known company and has a lot of products in the field. If your computer can handle its modest requirements.... then Go for it!
And have fun...
--TK
ETA: I found this:
https://www.youtube.com/watch?v=m1WVZf5cuQE
TinselKoala, I think you are right. I mean, you convinced me. I had my concerns and doubts because, as I told at the beginning, I'm kind of lost in this issue. I think you are right and this Hantek one is a good bet for my first oscilloscope. I'll go for it and I'll tell you all guys, how it is going.
BTW, thanks for the manual and the video.
http://www.ebay.com/itm/Hantek-6022BE-PC-Based-USB-Digital-Storag-Oscilloscope-2-Channels-20MHz-48MSa-s-/271265189899 (http://www.ebay.com/itm/Hantek-6022BE-PC-Based-USB-Digital-Storag-Oscilloscope-2-Channels-20MHz-48MSa-s-/271265189899)
Here is a Hantek scope on ebay for $68.50 USD. That sounds like a decent price. I doubt if my pc could handle it though.
Bill
Quote from: Pirate88179 on October 01, 2013, 07:59:04 PM
http://www.ebay.com/itm/Hantek-6022BE-PC-Based-USB-Digital-Storag-Oscilloscope-2-Channels-20MHz-48MSa-s-/271265189899 (http://www.ebay.com/itm/Hantek-6022BE-PC-Based-USB-Digital-Storag-Oscilloscope-2-Channels-20MHz-48MSa-s-/271265189899)
Here is a Hantek scope on ebay for $68.50 USD.
I notice that it is 20MHZ and 48 Million samples per sec.
How do we work out what specification is needed?
Hi everyone and (late) merry Christmas.
Eventually I got that Hantek 6022be oscilloscope for Christmas ;). Thanks for all of your advice, guys. I think it is a good acquisition. it is very easy to install and the use of its software is very intuitive, likely very simple but for me it is good enough so far, although it has things that are kind of improvable, as for example it shows a constant noise of a few mV.
Anyway, I've been playing with it and the circuit I built (a circuit that generates a signal of 1MHz based on a Hartley oscillator) and i realised about something quite curious.
When I use my Hantek oscilloscope in my plugged laptop, the Hantek oscilloscope's diode shows a patern like this: green-green-green-red (which I still don't know what it means and this is another thing I miss from its manual) displaying a 50 Hz signal (conected to my1MHz circuit). The first thing I thoughtis that I made a mistake building my circuit. But then I unplugged my laptop and the diode was all green (which I understand as nothing is going to explode) and the signal it displays is less stable and around 1MHz. (Mine! and although it is not very stable i'm proud of it!!)
So, is it possible that when my computer is plugged it establishes a short cut somehow with the current entering into my house which also is 50Hz frecuency?? Which is weird becasue it means I never can work plugged.
I attached to screen shots of those to situations
BTW, the wave I expected from my Hartley circut is a sine like one, but the previous one (plugged) has a weird shape to me and i don't know if for you guys it will mean something.
Thanks!!
I can't quite figure out what is going on there, but something sure doesn't seem right.
Can you show the screenshots that you get when you run the scope's "probe compensation adjustment" routine, done with and without the PC power supply plugged in? See the Manual, part 1.6, page 12.
http://www.electronicaestudio.com/docs/Hantek6022BE_Manual.pdf
You can also run the "function check", part 1.7, and the internal self calibration, 1.8, to make sure the scope itself is set up and working properly.
Thanks for your advise TinselKoala.
I already did all of the things you say, but I've done them again just to double (or triple) check. I post the screen shots I took this last time.
Probe compensation: first one is plugged and the second one unplugged
The fuctional check is ok. I've tried plugged and unplugged PC and using both probes. All of them displayed the same results. According with its User's guide it has to show a wave of 2V peak to peak and a frecuecy of 1KHz aprox., and tha's what I get so everything is all right, then. Also I tried once more to calibrate being my PC unplagged.
After all of this, the same situation I explained previously remains.
Maybe the explanation does not go further than the fact that it is a cheap oscilloscope and it has its own limitations. What do you thing after all of this?
Thanks!!
The calibration traces are showing that there isn't anything wrong with your scope, like a noisy AC power supply or something. I doubt if the "cheap oscilloscope limitations" have anything to do with this problem.
OK, let's figure this out.
In the post here
http://www.overunity.com/13842/best-oscilloscope-choice/msg381997/#msg381997 (http://www.overunity.com/13842/best-oscilloscope-choice/msg381997/#msg381997)
you are showing the traces at vastly different timebases, so I can't evaluate just what's happening.
But from your description it does sound like you are making a groundloop somehow.
Can you please post the schematic of your Hartley oscillator, including power supply, and show just where and how you are connecting the oscilloscope probes and ground references?
Ok, i decided to solve that oscilloscope problem for myself. This is everyones problem, for anything not changing one needs a multimeter, but the next thing one needs is an oscilloscope, to measure anything changing.
So i bought an old oscilloscope from ebay. This is a 2 channel 20mhz oscilloscope hitachi v-222, and i got it for $50 without shipping. 20mhz oscilloscopes are one of the cheapest, because they produced them the most, often cheaper than any older vintage oscilloscopes. This oscilloscope was made some time in 1980's. But such oscilloscope is not outdated, they produce and use very similar analog oscilloscopes today, and nothing essential is changed in the electronics there.
Hitachi oscilloscopes are somewhat smaller, it weighs 14 pounds or 6.5 kg, but there are even lighter ones, neither does it take much room at the corner of a table.
$50 is cheaper than most usb oscilloscope, pocket oscilloscopes or scopemeters. But such cheap ones are not more than toys, less than 5mhz real bandwidth, many other things worse. Some have only one channel and even no external triggering. But this one is a fully functional oscilloscope with full power, no need to worry about any bad shortcomings. Robust and decoupled from everything, thanks to good old transformer.
So i may shortly describe the experience i got, in buying such things. Its better to buy from sellers who have sold at least several thousand items, with a possibly higher rating. But what i considered the most important, was that there were evidence that the oscilloscope were tested. That there are pictures of test signals on the screen, and sometimes even some small faults found is rather positive than negative, because this confirms again that the item was tested. That the basic things work, this is important for two reasons. First one may not be good at repairing the oscilloscopes. But even when one can do it well, when the basic things work say after 30 years, then this confirms that it is not made of any bad series of components, and thus the electronics may work a 100 more years without repair.
When buying old oscilloscopes, what you mostly get, is only the oscilloscope itself, no probes, no power cord, no manual. But this is not a big problem, as one can get two probes for $8, the higher frequency the better, a standard computer power cord usually fits well as a power cord, and the service manuals of most of the more widespread old scopes can be downloaded from internet for free. So you get all the description, calibration instructions, and circuit diagrams.
So in what shape was my scope when it arrived? It switched on and showed two lines on the screen, so i sighed with easy, at least the power supply and the crt tube works, without these it can be unrepairable. So then i took some wires, as i have no probes yet, and connected the calibrator output (every scope has a calibrator which generates a 1khz 0.5v square signal) to the inputs of both channels. There was the first disappointment, the second channel didn't work at all.
But then, after i switched all the switches many times, absolutely everything started to work. I also tested it with an AC wall adapter output. The trigger level adjusted fine on both channels, and the trigger was completely stable. On the old scopes which have stayed unused for many years, the switches get oxidized or dirty, whatever happens because of not moving them. This is normal, after moving them many times they work well again, even no need for a contact cleaning spray. In case if that is necessary, it should be a proper one which both removes oxide and lubricates, but if really necessary, one can buy such for less than $5.
So now i have a fully working 2 channel 20mhz scope, works well and looks nice too. I see that the knobs are almost not worn at all, so likely it is not even used much. I guess most old scopes are not much used, only a small part of then had been used intensively. I'm very happy with that scope, i never regret buying it, it rather makes me feel good, and more human-like, kind of. And doesn't it look nice? :)
So i hope there was some use of what i wrote here, for anyone who also needs to buy ones first oscilloscope.
Ayeaye:
Good post. I am sure this will help a lot of folks. I already posted about mine from ebay for $100 and I am very happy with it. (Tektronix 2213) Mine is from the 80's also and is 20 MHz. I am sure yours will do what mine does just fine. $50 is a real deal.
Thanks for sharing,
Bill
Thank you Pirate88179 :)
As much as i know, Tektronix 2213 is 60 MHz, but i may be wrong. Tektronix 2205 is 20 MHz, as much as i know. Anyway, Tektronix started to produce the scopes with that form and design, in the beginning of 1980's, then they started to make similar ones in Japan. This is a typical 1980's scope. What concerns using it, my scope is almost identical to these Tektronix's, the knobs do everything exactly the same, calibration is similar as well, the only difference is the location of the knobs. Inside it is a bit different, Tektronix has one big board, mine has two smaller boards one on another, one of these is upside down.
Many companies made very similar scopes, so one can buy any 2 channel 20 MHz or more scope by Hitachi, Iwatsu, Kikusui, Hameg, Philips, Elenco, Tenma, Leader, Trio, Kenwood, BK Precision, Beckman, i guess i named the most widespread ones of that type of scopes. Search like "Hitachi oscilloscope", and then the cheapest. A lot to search i know, but not so terribly lot. Tektronix one cannot find that way, there are too many plugins and accessories. Tektronix also used to be somewhat more expensive, but it is high quality and its manuals are very detail and good.
In my opinion, what concerns the cheap USB oscilloscopes, then their rise time is quite good, also they tolerate at least 300 volts input voltage the same as big scopes. The rise time doesn't mean an equivalent bandwidth with the analog scope with the same rise time though. Because the analog scopes can rise and fall much faster with less vertical distance. So it is considered that the bandwidth of the digital scope is its sample rate divided by 10, but because of two channels, it has to be divided by 20. Thus a typical 40 Ms/s cheap USB scope really has a bandwidth only 2 MHz, of an equivalent analog scope. Not 20 MHz as it is said, this 20 MHz may only be true, what concerns the rise time.
The cheap USB scopes also have not quite good electronics, with too much all kind of interference. They often have a faulty software. They don't work with every USB connection, like that in virtualbox. They are coupled to the computer's ground, which some may say is not a bad thing, then others may still want to use a floating scope. If they know what they are doing, that is. And they are inconvenient, have to be connected to the computer, software started, etc.
The USB scopes they consider "cheap scopes", and thus they make them as cheap scopes. That is, they don't care about the electronics quality, or the software quality. But when buying an old scope like mine, in spite its cheap, you get a scope which once wasn't cheap and was not made or designed as cheap. So when it is made to work, it is a good scope with high quality. A serious measuring equipment, not a toy by any means. Its really sad that they don't make good low end scopes any more. Once a beginner could get some cheap one channel 10 MHz analog scope (usually with an external triggering), which was slow and had a minimal functionality, but otherwise was a good and decent scope. But today, the beginner is supposed to use a cheap USB or pocket scope, which is a lot inferior to that 10 MHz analog scope.
Yep, I have a 2213a which is 60 MHz and I believe that the 2213 is the same. I paid 125 Canadian for mine from Active Surplus on Queen Street East in Toronto, lugged it home on the subway. It's a lot lighter than many old scopes so it wasn't too hard.
There is a difference in the input attenuator board, the 2213a has the same switches and attenuator/preamp board as the 2215 instead of the 2213. This caused me a little difficulty when I had to replace an input FET on one side... I had the Service Manual for the 2213 and when I opened up my scope it was different inside! But the 2215 Service Manual had the right information that I needed, including how to disassemble those complicated range switches.
The scope is excellent, I use it a lot for general purpose work since it is so easy to use, warms up fast and the delayed timebase and variable-holdoff trigger functions are great to have. Crisp and bright display too.
Yes, I made an error...the 2213 is 60 mghz. What the heck was i thinking?
Bill
Quote from: Pirate88179 on February 09, 2015, 07:46:25 PM
Yes, I made an error...the 2213 is 60 mghz. What the heck was i thinking?
Bill
You should have been thinking: That's like 40MHz free bandwidth! Can free bandwidth be turned into free energy?
Quote from: MarkE on February 09, 2015, 07:57:21 PM
You should have been thinking: That's like 40MHz free bandwidth! Can free bandwidth be turned into free energy?
I'll check with EMJ. If anyone can turn free bandwidth into free energy (in his mind anyway) he can.
Bill
Bill,
I didn't want to emphasize that you made a mistake, i'm so sorry. I wanted to say that you were right that both the Tektronix 2200 series and my scope were made in 1980's, and were 20 MHz and 60 MHz. Many other companies made similar ones. They all had the same design, a large rectangular crt tube, and knobs to the right of it, also were lighter than the previous ones (i guess all of them should be less than 15 pounds). The knobs on all of these do all the same things, and their electronics is similar as well.
I agree that Tektronix is the best, but one can also do with a cheaper one, which is one of these scopes like mine, made by other companies, similar to Tektronix 2200 series. There are disadvantages of course, like i can nowhere get the instructions how to disassemble the switches in my scope, when paid less one certainly gets less. Yet one can get a decent working scope. My screen is 6 inches, crisp and bright as well, and all is nice and stable. A completely useful scope.
They sell now one in ebay that is exactly mine, hitachi v-222, for $50. If you are in America, you may get it with $15 shipping, so all you pay is $65. It is not test signal though what it shows on the screen, so this one may or may not work, but it is certainly repairable. Mine was better, on the photo there were two sine signals on the screen, this showed that both the vertical system and the triggering works. And indeed it finally appeared to be a completely working scope, with no repair.
http://www.ebay.com/itm/Hitachi-Model-V-222-20MHz-2-Channel-Oscilloscope-/171677138055?pt=LH_DefaultDomain_0&hash=item27f8c13c87 (http://www.ebay.com/itm/Hitachi-Model-V-222-20MHz-2-Channel-Oscilloscope-/171677138055?pt=LH_DefaultDomain_0&hash=item27f8c13c87)
Old oscilloscopes are mostly sold without probes. It is possible to use wires instead, but wires don't give a good contact, cause interferences, and they cannot be pushed in too hard, to not damage the oscilloscope's connector. So i bought 100MHz oscilloscope probes from eBay for $8 with shipping. The following video is about unpacking and testing them, sorry for the mistakes which i made, please read the description.
https://archive.org/details/probes_201503 (https://archive.org/details/probes_201503)
I think i should exactify what i said about buying old analog oscilloscopes. As anyway i have responsibility. From the companies i said, it is said Trio and Kenwood oscilloscopes are not good, so avoid these. Others said not to be good, are Heathkit and Bell & Howell, so avoid these, in spite they often are the cheapest. What this guy from eevblog said to be good other than Tektronix, are Hitachi, GoldStar, Kikusui and Hameg. Also HP, but some say HP oscilloscopes are not so good. This guy knows what he says. He especially said that Hitachi is good, so prefer that, it's like the next best after Tektronix.
Some others who can be trusted, said that Iwatsu is good, also Leader. There is not so good information about the others, so see the reviews and learn more. BK Precision also seems to be appreciated, also some serious people seem to use Beckman and Philips. There was an excellent demonstration of a Tenma oscilloscope, and this oscilloscope performed just wonderfully, better than any other i have seen. But it was said, that such oscilloscopes, different from Tektronix, are not based on military standards. So when if buy Tektronix, you get a good thing, but then you pay twice more.
About the very old oscilloscopes, like these with vacuum tubes, the only ones they say can be used, are Eico and Telequipment. Like one can get an Eico 460 worth to buy from ebay in America, for $50 with shipping. These are only 4.5 MHz one channel, but one may find a use for them. One should consider with so old oscilloscopes though, that you most likely should replace just everything there, other than the crt tube and power supply transformer, so make sure these work. At that vacuum tubes don't seem to be a problem at all, as they seemingly can always be bought from ebay, so in spite of how it may seem, vacuum tubes are not really things to avoid. It is possible to get service manuals online, for almost all these. But it may cost to you more than buying a good 1980's 20 MHz two channel oscilloscope, so it is not exactly minimalism what concerns money, it may be minimalism just for the sake of it, or when you love restoring old oscilloscopes.
My oscilloscope still works fine. Except when i don't use it for some time, the potentiometers and switches somewhat play, until i move them back and forth a bit, then they work fine again. But that's normal.
Why some oscilloscopes are not so good, like some analog oscilloscopes or pocket or usb oscilloscopes. Because their circuits, such as amplifies and triggering, are so primitive. Things become more complicated when measuring changing things, Like the amplifies themselves contain capacitances and whatever, which cause distortion and interference. So what can be wrong. Everything can be wrong you can imagine. The can be unstable, like show different values at different times, with no way to fix it. They may distort the signal. The may cause interference, like additional oscillations in your signal. They may make the signal to be unstable and change fast, when it really doesn't. Because of instability of the signal or a primitive triggering system, they often may not be able to trigger. At that things may be fine, when you just measure a 60 Hz sine signal, but you see problems when you go to any higher frequency or hae a more complex signal. At that, it may not be fine even then. Like some Heathkit oscilloscopes show some sharp angle at the bottom of the most perfect sine signal. More than that, some even show you always a sine signal, no matter what the shape of your signal is.
So consider, this need for quality, is not for having a very high precision measuring equipment. So one should consider these requirements, just to have an instrument which you really can use for measurements. Not a thing which shows funny things on a screen, which may also look like nice, but that really cannot be used for anything useful. Especially when you are using it for things like overunity, one should be especially careful, as measurement is everything there.
When buying an oscilloscope, as i said, the best when on its picture there is a signal on the screen, especially when you don't feel being able to repair an oscilloscope. But this eevblog guy said, it's enough when they say that it is working. Then the very minimum is, that it's said that it powers on, and something appears on the screen, like a dot. Less than that, don't even consider buying, unless you need some spare parts from that particular scope. Because when the power supply transformer or the crt tube doesn't work, then this scope cannot be even repaired. Don't rely on sellers saying that this scope was just not tested, or they cannot or have no means to test it, this doesn't assure you anything, and it's also often questionable, that they pretend to be so stupid that they cannot test an oscilloscope anyhow. Don't rely on statements like, the oscilloscope is in good condition, this may mean anything, like it looks nice, but its crt tube doesn't work. Look for clearly saying that it works, because when it works, there is no reason that prevents the seller from clearly saying so.
About auctions, it is better to buy items from ebay, that you can buy at once. Because auctions are often a anipulation in ebay. Consider most of the bids mostly come in the very end of the auction. The buyer can also in some cases choose not to sell to the highest bid, so he can use his sock puppet or a good friend or business partner, just to pump the price up. What concerns old oscilloscopes though, auctions can sometimes be considered. Like there are auctions where they couldn't sell the oscilloscope at all, and sometimes it's an oscilloscope worth to buy, which one can get cheaply. It is possible to see in ebay, what items were actually sold, and with what price. So when you see an oscilloscope in an auction worth to buy, and before the very end of the auction there were no bids at all, you may consider buying it, you may get a bargain. But avoid the hazard, that is, maybe i can get it cheaply, think seriously about the reasons before going for anything.
I also found a new method of using oscilloscope. Like, often you have to calculate a power, and all you have are oscilloscope images, like of the voltage and current. Then what you can do, is to draw these graphs in gschem. Gschem has a very simple output file, just a text file for vector graphics. And from that file, like use python to calculate the bower based on two graphs of the oscilloscope signals.
What concerns my oscilloscope, i didn't have to do any repair. All i did, was a minimal calibration based on the oscilloscope's calibration signal, and even that was almost correct. The biggest problem was the cleaning. I used a strong cleaning agent for painted surfaces, no it doesn't damage plastic parts neither make them less shining, but you may first try out at some less visible place. Plus some graffiti removal pads maybe. I got it nicely clean, even the yellow on the light plastic parts, goes away with this. The only problem, the paint seems to be somewhat oxidized, as it is darker than it originally was. Some paint polisher may improve that, but i did not risk that, to damage the paint anyhow. It is also no problem to paint the metal case, it can be easily taken apart so that only the sheet metal remains. But this is not necessarily a good thing to do, as the original paint is a great value.
The metal parts i cleaned only with a tooth paste, maybe a lack of my imagination, but it was enough, makes them nicely shining, removing dirt and also oxide. The moving parts of the handler needed oiling, for which i used vaseline. The knobs are sometimes somewhat bent, as they hit them with heavy objects or then like to put the oscilloscope to stand on its knobs, doing that carelessly. A knob has a long rod, that is fixed at one end with a screw or something. It can be taken out and bent straight. I have one knob bent slightly, which is almost not noticeable, and causes no problems. But i did not risk to make it straight because this is a somewhat risky, as the rod has to be perfectly straight. I could make my scope nice and decent looking, all i think is necessary. I wrote this just to give you some idea of what it takes. Nothing much, it's mostly just cleaning. Unless there is some knob missing or such, and you have to replace it with some 3D printed one, or something. But in this selfless overunity effort, using an oscilloscope with some knobs missing, is i think a sign of pride.
Oscilloscopes, these things show us the nature. Not what we used to see nature is, but nevertheless it's nature, the ways we may not used to think about it. Beautiful as it always is.
Hope this was useful for some. And hope that it makes you not to hesitate to buy an old oscilloscope. The risk is not so great as you think, if you think everything well through, i think in 90% of the cases you will get a good working oscilloscope. And you will discover what a fun dealing with such old oscilloscopes, really gives you.
Ebay has some good values for the money.
Here is a Sinometer brand for under $200 with free shipping.
.
Quote from: FatBird on January 13, 2016, 02:01:09 PM
Ebay has some good values for the money.
Here is a Sinometer brand for under $200 with free shipping. .
Your having a larff it's got nothing on it, i wouldn't wast your money! you can get a Regol DS 1054z for £250 and look at the diffidence !
https://www.rigol-uk.co.uk/Rigol-DS1054Z-Digital-Oscilloscope-p/ds1054z.htm#.VpbSBlIVvcshttps://www.rigol-uk.co.uk/Rigol-DS1054Z-Digital-Oscilloscope-p/ds1054z.htm#.VpbSBlIVvcs
Quote from: FatBird on January 13, 2016, 02:01:09 PM
Ebay has some good values for the money.
Here is a Sinometer brand for under $200 with free shipping.
$200 with shipping, good value for money? I'm talking about old oscilloscopes one can buy from $50 with shipping, to $100. Good, completely working oscilloscopes, one can use for anything.
But you have $200 to spend? Great, then buy this one http://www.ebay.com/itm/Tektronix-Tek-465-Oscilloscope-with-Factory-Installed-DM43-Multimeter-/281903775425?hash=item41a2c63ec1:g:wQIAAOSwZG9Wjx2s Tektronix 465, 2 channel 100 MHz, refurbished, calibrated, tested, has probes, excellent scope. The same TinselKoala had, if i'm not mistaken, ask him, he can tell you plenty of things about it. And all for $186 with shipping if you are in America. That is, it depends on where you are in America, but if you are in America, you can certainly get it for less than $200 with shipping. If you are in Europe, you should find scopes sold in Europe, as these things are heavy and their shipping costs a lot. But i don't know where you are, so i brought that as an example. Now compare that to this 10 MHz single channel Sinometer, these things cannot be compared, simply cannot be. This Tektronix is so good that i cannot even dream to have a so good scope, yet i'm satisfied with the one i have, it is a good scope and works well.
But this Sinometer. 10 MHz, one channel. Ok, you don't need more than 10 MHz, Ok, you can do with one channel, as it has an external sync. But this frequency is not only about range, it is about quality. These scopes are known to give different readings at different times, they are also likely unstable, and have plenty of interferences. Some people say, they can only be used to see wave forms, and it it is a question how reliably they do even that. So you want to buy that for $200, just to find that this is true? And nothing can be done about it, this is caused by its primitive circuit. You will find that it's just useless for anything. And after a year ago it will make a buff of smoke, and seizes to work beyond repair, as some people have said. They make many similar scopes, but they are all the same, likely made in the same factory in China, only the case differs a bit. They are known to be the most primitive, and made carelessly. They are low quality not only what concerns the electronics, but their physical parts often break as well.
Yes they are small, and resemble some old oscilloscopes with vacuum tubes, though they have no vacuum tubes. This also includes a tiny screen, which is not good at all, but overall yes, they look lovely. But all the negative about them still makes that worthless. And small, an oscilloscope doesn't take so much room, you can manage to put one at the corner of your desk. And, like having a Tektronix oscilloscope on your desk, this looks great, impressive for everyone who sees it. Everyone has computers, but not many have oscilloscopes.
But this thing, it is minimal, right. But i don't understand such minimalism. If you are minimalist in that way, you should rather buy an old Eico 460, you can get one for $50 with shipping http://www.ebay.com/itm/Vintage-Eico-Model-460-Wide-Band-Oscilloscope-Electronics-Repair-Tester-/231807804023?hash=item35f8d26277:g:aUwAAOSwJkJWkCDs It is 4.5 MHz, one channel, and has triggering and external sync. And make it to serve you well. That one you can actually use, in spite old, it is a usable oscilloscope. Different from that Sinometer, do all you can to keep away from that scope.
I'm sorry for this Tektronix 465 i referred to. I selected "buy it now" in ebay, and also only looked at oscilloscopes with "buy it now". So it had to be "buy it now" when i found it, it is very unlikely that i didn't notice the auction. I don't know what it is, but something is wrong there. That oscilloscope is most likely good, but the seller may screw up the price, using weird tricks. So, sorry again and be careful.
EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
Relationship between: - Frequency of circuit under test and Mhz, sample rate of scope needed
EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
.
Understanding this is vital. Can someone explain how to arrive at the required Mhz and sample rate needed to examine frequencies under test?
(Slow running motors should be able to use the Winscope software, with probes going into the soundcard)
1. No, I don't have a Tek 465, but they are fine scopes, if a bit complicated for a beginner. If you buy one make sure it's working 100 percent. They may have problems with switches and pots, due to age, but these are usually easily fixed by exercise and cleaning. Ask the seller, make sure you can return it if not working properly.
2. Don't buy a single-channel scope. These are special purpose items and are not as useful as a two-channel instrument. You will often want to look at the relationship between two (or more) signals and there is no way to do this if you only have one channel available.
3. Stay away from very old scopes like that Eico. They will probably need to have most or all of their electrolytic capacitors replaced in order to work properly. Unless you are a collector or just like fixing old stuff, it's not worth it for someone who wants an instrument that is actually useful on the bench.
4. The general rule about bandwidth is 5 times the fundamental frequency of the signal you want to examine. So a 100 MHz scope will "honestly" tell you what's going on in a 20 MHz signal, as far as risetime and amplitude is concerned. Of course you can use the scope for higher frequencies, but it won't show you the true amplitude of the signal nor will it accurately report rise times or other fast transient phenomena. This is true whether the scope is analog or digital. But DSOs have another thing to worry about: Aliasing. They can show you a completely different waveshape than what you are feeding into it, depending on sample rate. This is one thing you don't have to worry about with an analog scope.
5. While (almost) any scope is better than no scope at all, I would recommend staying away from "sound card" scopes or USB scopes that use your computer as display and control. Sound-card scopes have very low bandwidth and are clumsy to use. USB scopes can be good, but the good ones are as expensive as a low-end bench DSO. The cheap ones like the 20 MHz 60-dollar Hantek... well, I suppose they are better than no scope at all, and they do come with a set of probes that would cost about 20 dollars just on their own.
My advice: for between 100 and 200 dollars, look for a simple analog scope like the Tektronix 2213a or 2215a or similar 60-100Mhz bandwidth 2-channel unit. For 200-400 dollars --- save up and get something like a Siglent 1000 series or a Rigol DS1054z. If you absolutely must have a scope right now and you can't afford more than 100 dollars for the foreseeable future, consider a USB scope like the 20MHz Hantek, but beware....
And have fun! The oscilloscope is the King of Test Equipment and no electronics experimenter's workbench is complete without one.
That's a handy rule of thumb, TK. x5.
What about sample rate? How does that fit in (apart from some sort of "the more the merrier" yardstick?)
back in the late 80's, early 90's they developed processors that clocked in the Ghz range,
and along with them came scopes that could read the signals.
of course, just like most of the "real technology" of our world, we don't get to play with them for about 50 yrs after development, and while that time is approaching, they are still tens of thousands of dollars, and out of reach of the average person.
By the time we can get them, our computers will be running on synthetic diamond processors clocking in the TerraHertz, and most people wont see THOSE scopes till the year ~2058
(THz O-scopes were fully functional by 2008, using two different technologies)
TK gives good advice on the low-range scopes, I've owned a few, but most of what I care to play with these days is far beyond the reach of an affordable scope.
really kewl stuff happens at wavelengths approaching the atomic resonance scale :)
All i know about how the bandwidth of an analog oscilloscope is defined, is that it is the frequency where there sine signal is reduced to 70% of its original. Higher than that frequency, and almost nothing comes through. And this is only about sine wave, any harmonics you want to see, must also be within that bandwidth.
What concerns the USB oscilloscopes, then i rather prefer to have a glorious decent old scope, with all the funny things on it, than this small cheap box containing some questionable electronics, and you can get it for the same price or cheaper. Also that eevblog guy doesn't quite agree with TinselKoala about these cheap USB scopes, and i trust that guy, he really knows what he says. They should start to make some cheap analog scopes for the beginners again, as they once did, but they don't, and this Sinometer is just an accident.
What concerns the Eico, i meant, who is truly a minimalist and wants to have a minimal scope, should rather consider buying that old Eico, than that Sinometer. Yes i know one may end up replacing almost all components there, but when one is such a minimalist that can go to buying that Sinometer scope, just to have a minimal scope, then much better would be to buy that Eico. Because there will be an equal trouble of doing anything at all with both of them, but when one repairs Eico, then at least one would have a useful scope, though only minimal. But this will never happen with that Sinometer scope, even when one is very good at electronics, one likely cannot make it anyhow useful, because of the flaw of just everything in it. Who doesn't want to repair a scope at all, as i said, should buy a working scope, but pay somewhat more, though not much. As i did, and i got a scope which i didn't have to repair at all, and it works well until this day.
Old Tektronix scopes tend to be expensive in ebay, and much more tricky to buy, because they are the most sought after. This is why i talked about other alternatives of old scopes, which one can get much more cheaply from ebay, but that are still good working oscilloscopes, all what a beginner may need. Like this LG (GoldStar?) oscilloscope, $110 with free shipping, it has a test signal on the screen, and it is evidently working http://www.ebay.com/itm/LG-Dual-Channel-Oscilloscope-Model-OS-5020-20mhz-/331680874379?hash=item4d39b87f8b:g:mUUAAOSwo6lWHUId . But it is likely a good oscilloscope. This was "buy it now" when i posted this, when now the seller again changes to auction, be careful and notice that and better avoid buying it, but please don't blame me then.
Old scopes should not be wasted, they should be added to the armory of overunity researchers :)
Ok, this is a video about that Sinometer 10 MHz scope https://www.youtube.com/watch?v=EutGR4xbs48 . I'm certain that this is exactly the same, as they sell these cheap scopes under many different names, but all of them are exactly the same.
200 Hz, a frequency which should not cause any problems, and it doesn't seem to even trigger. He touched the trigger adjustment knob, but apparently found that it cannot trigger. Why they chose 200 Hz when they could choose any frequency, may well be that on higher frequencies the signal is just horrible. And even with that 200 Hz, other people say, the amplitude it shows is different every time you measure.
Why does the intensity of the signal on that Sinometer vary so much? The image below is during showing that 200 Hz sine signal, this is all that is visible on the screen at a time.
I don't know what this thing is, but it is not oscilloscope the way i used to know oscilloscope is. It seems to be some piece of scrap electronics, just named oscilloscope, so that people would buy it.
I could once even buy that oscilloscope, that is some of the types of it, which i'm sure they are all exactly the same. I hesitated between that, and that Hitachi oscilloscope. I'm so glad that i decided to buy that old Hitachi oscilloscope, as now i have a normal working scope.
That it is 20 MHz and two channels, makes me a bit sad, as i'm minimalist. But i had nothing to choose from, because i didn't want to go to replacing all parts of a vacuum tube oscilloscope, also Heathkit and Bell & Howell they say are not good and reliable, so there was nothing else to choose. Also at the time i didn't feel to be able to repair oscilloscopes in any way. And the cheapest dso or usb oscilloscopes were not cheaper, and i didn't find them to be any usable oscilloscopes either.
So i, kind of, found that the 20 Mhz 2 channel oscilloscope is not that bad. These were the oscilloscopes they made the most, so there is the greatest supply and the price is the cheapest. So i guess one has to satisfy with a 20 Mhz 2 channel scope, unless one succeeds to find any less powerful oscilloscope, that is also working, which is a matter of a kind of rare chance. And an oscilloscope which is not Heathkit, Bell & Howell, Trio or Kenwood don't know more old oscilloscopes that they definitely recommend not to buy, but there may well be more.
So realistically, the choice is either some 20 MHz or more two channel oscilloscope from 1980's or 1990's, or then an old Eico or Telequipment oscilloscope with vacuum tubes, with replacing most of the parts inside. The latter is the right choice for a true minimalist, who also can do some electronics, well, not a rocket science is necessary for that. Provided that doing that also gives fun. Why i say Eico or Telequipment, because, other old oscilloscopes with vacuum tubes are not said to be usable. You may find out more, and maybe there are some that are, but most are Heathkit tha certainly are not. Also with such old vacuum tube oscilloscopes there is a high risk that there are no regulators or anything, so you get some rather arbitrary readings, which is not true for Eico or Telequipment, they are often very simplistic. One may say, there are also old Tektronix scopes with vacuum tubes. There are, but Tektronix oscilloscopes with vacuum tubes tend to be huge, with a large number of vacuum tubes. Thus these are not really realistic options.
What concerns this sinometer oscilloscope, dso oscilloscopes, usb oscilloscopes and all sorts of other scrap, or oscilloscopes made of an old crt tv-s, then one more option is to make the circuit yourself. This option though is the most difficult of them all, as a really usable oscilloscope's circuit is not simple at all, it is very complicated. It is also not stardard, and depends on the particular crt tube, components or whatever you use. So this is for people who know electronics very well, thus it is not any option for beginners.
But i think, unfortunately very likely you would have to satisfy with a 20 Mhz 2 channel analog scope, and not anything less. As bad as it may sound.
What concerns auctions, i say, never go to auctions, buy only these that are "buy it now", most items are such and there is plenty to choose from. But if you still decide to go to the auction, then. The most reasonable is to go to auction when until a few hours before the end of the auction, there are still no bids. But when you still decide to participate in an auction otherwise, then. Start bidding only a few hours before the end of the auction. Find out the price of the similar items, and decide the reasonable price with which it makes sense to buy that item. Then bid only to that price and never higher, suppress the hazard to bid a bit more. Because, the seller or his business partner, may be your opposite bidder. If that's so, and the auction ends, that opposite bidder will not agree to buy the item, and the item is yours with the reasonable price, you bid it to. Also other bidders may refuse to buy the item, when they bid too high, and again the item is yours. But again, never go to auctions, this is an unnecessary waste of time and effort, too risky at well. Good sellers also rarely sell items on auctions, they don't play any games and waste their time to that, their only business is selling their goods.
One more thing, the price of shipping. Some think, what matters is the price of the item, and the price of shipping is some inevitable expense, in addition to that. But you should know that you pay the price of shipping to the seller, and thus it can be that the seller gets an additional income by setting the item's price low, but the shipping price high. You cannot see the real shipping price anywhere, even when you receive the item. You may deduce it from the shipping price of a similar items by the same shipping service, but even there are several options. It doesn't really matter for the seller, which way it is. Thus always consider the price together with the price for shipping. Find out the reasonable prices for shipping for similar items, and think twice when the shipping price is much higher than that. Use the cheapest shipping options, don't choose the more expensive ones, they don't guarantee that your item arrives in better condition. Don't choose fast shipping as the time is almost never that critical, and it is a real waste of money.
Hope that was anyhow useful for anyone.
As you see on that Eico 460 that they sell in ebay, different from that below, the horizontal selector is on external, which means that it is in x-y mode, and there can only be a dot on the screen when no probes are connected.
It is difficult, as i'm not any expert in oscilloscopes, yet i have to explain. So i try, have to try. By what people said, and based on what i read from its manual, Eico sems to be a so-called repetitive sweep oscilloscope, and so likely are most vacuum tube oscilloscopes. Repetitive sweep oscilloscopes are older types of oscilloscopes, which were there before triggered sweep oscilloscopes. Instead of triggering, these oscilloscopes seem to change the frequency of the sweep, to frequency which is the closest harmonics to the frequency of the measured signal. This means that they cannot be used to measure any time characteristics of the signal, because the sweep frequency varies and is not really known. Neither does it enable to measure the phase difference of two signals, in spite that it has an external sync. For that reason Eico likely is not a reasonable choice, it is not an oscilloscope in what we used to know oscilloscope is.
Eico 460 also has a non-standard input resistance, so the standard probes cannot be used, they should either be modified, or one should make ones own probes. There is the schematics of the probes though. It also can be used only with 120 V mains power, that is in America, it has no means to switch to 250 V. In spite that said, it is a useful oscilloscope that works well for certain purpose. Like it was widely used for tv repair.
Thus the only oscilloscopes worth to consider with vacuum tubes that i can say, are Telequipment oscilloscopes, like the s51b below, from 1970. This oscilloscope has triggering, that is, it is a triggered sweep oscilloscope like all the modern oscilloscopes. It also has an external triggering. Telequipment was a branch of Tektronix, making not as good oscilloscopes as Tektronix, yet for that reason all its oscilloscopes seem to have triggering. This may be a reasonable alternative to that Sinometer, if one is a true minimalist, but likely after some repair. It can be used with both 120 V and 250 V mains power. An example of it sold in ebay http://www.ebay.com/itm/Vintage-Telequipment-Oscilloscope-S-51B-/111207579502?hash=item19e47cff6e:g:a5wAAOxyLN9SeBSJ , this one costs $72 with shipping to America. It has at least a dot on the screen, so it is at least repairable. But if repairing old oscilloscopes doesn't interest you, an old 20 MHz 2 channel oscilloscope is still better for you.
At that this Leader oscilloscope is said to be "tested for all functions" (does it mean that it's working?) and it's only $69 with shipping to America, so less than this vacuum tubes oscilloscope, and it's 20 MHz and two channels [search ebay for Leader 1021, and the cheapest, the url makes all the text here too wide] . It is a scope from 1980's likely though, so likely doesn't satisfy true minimalists, but what concerns price, it may not make sense to buy less powerful oscilloscopes.
Hope this helped to make things more clear.
the 2 best ways ive found to get a quality scope at an affordable price is:
1) take the time to go to Estate Sales until you luck out.,
and
2) the U.S. Education spares no expense on getting the good stuff.
when a school upgrades their equipment theres usually 30-50 scopes that get sold out the back door.
ive gotten a few this way over the years.
Quote from: sm0ky2 on January 23, 2016, 12:43:12 AM
2) the U.S. Education spares no expense on getting the good stuff.
when a school upgrades their equipment theres usually 30-50 scopes that get sold out the back door.
ive gotten a few this way over the years.
Surplus, yes, they sell old oscilloscopes in official auctions or something. These are mostly ones from 1980's, at least 20 MHz and two channels. Positive about that, is that they sell them cheaply, because they sell many of them, and thus really have no time to test whether they work or not. These scopes often end up in ebay, and the sellers also don't test them very thoroughly, as they sell many of them. So when seeing that the oscilloscope is one of such, there is a good chance to get an oscilloscope cheaply, which is better than its price may indicate. What shows that they may be some of these, is when they sell several oscilloscopes of the same type at once. I think my oscilloscope may also be one of these, as the seller in ebay sold two oscilloscopes of exactly the same type. And the other things, such oscilloscopes are sold quickly, thus they mostly are not cleaned at all, so another indication is that the oscilloscope is not made shiningly clean. Finding that it is one of these oscilloscopes, increases the trust that the seller doesn't try to cheat you with a scope that is worst than shown.
So indeed, the best option is to get some 20 MHz 2 channel oscilloscopes from 1980's. This may also be the cheapest option, because there is the biggest supply of these. I have always thought that, i told about the less powerful ones only for these who are true minimalists, and like to restore very old oscilloscopes. As this is a fun which many people cannot resist ;)
I don't think it is worth spending a lot and buying a new scope as a first one because we learn so much with the first one bought. When we know what we NEED, by looking at blurred and indistinct scope shots, then spend the cash and get the right one.
Some warn against the Heathkit and Bell & Howell oscilloscopes. They especially warn against Heathkit and Bell & Howell school oscilloscopes, and old Heathkit oscilloscopes with vacuum tubes. But i found a video https://www.youtube.com/watch?v=hoAmzsz_bJY which shows that a Heathkit IO-4205 oscilloscope works perfectly. This is a 5 MHz two channel oscilloscope made in 1980's, it is solid state, has triggering and modern probes fit to it, by schematics it can be used both with 120 V and 240 V mains power. Heathkit IO-4105 is a one channel version of it, but it has an external triggering. If true, this may be the cheapest reasonable option, because these oscilloscopes are the cheapest in ebay. Like there is one Heathkit IO-4105, that costs $53 with free shipping to America http://www.ebay.com/itm/Heathkit-Oscilloscope-10-4105-Working-Unit-Ships-FREE-/281908425196?hash=item41a30d31ec:g:mEsAAOSwJkJWlpeo , this one has though only a dot on the screen, but is said to be "in good overall working condition".
Some what they call school oscilloscopes, are Heathkit IO-4540, which is also named Bell & Howell I0D-4540. Heathkit and Bell & Howell oscilloscopes often seem to be completely identical, often with the exact same numbers. These look like completely identical to Heathkit IO-4105, but they are warned against and thus may not be the same inside. I found only one video in youtube about such oscilloscope, and it showed what was said to be its own calibration signal. This supposed to be sine, but it was a kind of distorted, weirdly angular. Maybe the oscilloscope's calibration signal was bad, maybe the distortion was caused by the oscilloscope, but whatever the case, it indicates a low quality of the oscilloscope. So for these reasons these oscilloscopes likely should be better avoided, in spite that they cost less in ebay than Heathkit IO-4105.
Perhaps this is all i could say about buying old oscilloscopes, from the little knowledge that i have. Hope it was anyhow useful for anyone.
And now... RM503 and the Four Oscillators present: Lissajous for You #2 (Best of)
http://www.youtube.com/watch?v=q55-CTCd2k4
Quote from: TinselKoala on January 26, 2016, 12:04:32 AM
And now... RM503 and the Four Oscillators present: Lissajous for You #2 (Best of)
http://www.youtube.com/watch?v=q55-CTCd2k4
Beautiful
Yes these Lissajous were really beautiful. This was an old tektronix with vacuum tubes, i guess, some of these are very precise instruments.
From my little knowledge, i try to explain how these old repetitive sweep oscilloscopes work, also called recurrent sweep oscilloscopes. Because these who may think about buying such old oscilloscope, should have some idea of what they get.
They made recurrent sweep oscilloscopes already in the 1940's and maybe even before. These made in 1940's look almost exactly like Eico 460, though they sold Eico 460 until 1976 or such.
These oscilloscopes were generally made before the triggering oscilloscopes. All i know about how they work, they say they feed a small amount of the input signal, to the horizontal sweep oscillator. I don't get a clear idea of how it works from that, but i understand that this somehow enables to synchronize the horizontal sweep oscillator, with the external signal, so the horizontal sweep frequency becomes some harmonic of the input signal frequency.
I noticed that recursive sweep oscilloscopes have a scale on the horizontal scale fine tuning knob, which triggering oscilloscopes almost never have. So i guess, you change the horizontal frequency, until luckily the signal on the screen stops for a moment. Then from that scale you can calculate frequency, though it is likely not very precise. Or some maybe enabled to find a Lissajous pattern with the external signal. Or you find frequency with an external function generator and a Lissajous pattern, if you luckily have one.
Then you switch to internal synchronization, turn the horizontal frequency knob again, and luckily can get the signal to stay still on the screen. Then, knowing the frequency before, it is possible to calculate the times. From the oscilloscope's settings at that time, it is not possible to find frequency, because the frequency is unknown, and depends on the frequency of the signal. Some simpler oscilloscopes, i understand, had a very slight internal synchronization, so no switch to switch it off, but they synchronized at the frequency very near the signal's frequency, so with some rough approximation, it was also possible to find the frequency.
It is also possible to synchronize with the external signal, like Eico 460 can do that. This is why on these scopes, the input is called external sync, not external triggering. And on this sinometer oscilloscope, it is also ominously called external sync. That way it should be possible to compare two signals, when the frequency of the external sync is known. Because it should synchronize always the same way then, the synchronization only depends on the external sync, and not on the input signal. Thus it should also be possible to measure a phase difference. Or that can be done with Lissajous, which is difficult or impossible though, when the shape of the signals is too complex.
Thus it may be possible to measure time characteristics with the recurrent sweep oscilloscopes, but this is much more difficult, inconvenient and much more imprecise, compared to the triggering oscilloscopes. If precise measurements of time characteristics are necessary, then these oscilloscopes may be useless for the task. The recurrent sweep oscilloscopes, when they were good, were very good for certain tasks, but not for others. This is why they were sold a long after the triggering oscilloscopes were widespread, as a "maintenance class" oscilloscopes.
This sinometer oscilloscope also may be a recurrent sweep oscilloscope, not a triggering oscilloscope. So this may be an additional pain, in addition to ways how it is a scrap otherwise. I'm telling this because i know that it is difficult to convince some to not to buy that sinometer oscilloscope, as it looks so appealing. This oscilloscope is an example of the new wave of chinese scrap products which start to enter the market. Be cautious about these, as they often are not what they look, or are believed to be. I mean, some of the cheap things they make, are still useful, but at one point they may become useless, or likely will, considering how the things develop further, and more "innovations" are added.
Determining frequency using the RM503 precision low-frequency oscilloscope:
http://www.youtube.com/watch?v=teXXF0a_WoI
Displaying a stored waveform from an analog oscilloscope:
http://www.youtube.com/watch?v=HcHg5gGB5xk
;)
Quote from: TinselKoala on February 02, 2016, 04:32:40 AM
Displaying a stored waveform from an analog oscilloscope:
http://www.youtube.com/watch?v=HcHg5gGB5xk
;)
Yeah that's clever, but... I figured out something else. It is possible to use gschem, to draw waveform, and as it is a vector graphics editor, then its file is easy to use for all kind of calculations, like with using python. That way it is possible to easily calculate power, from the waveforms of voltage and current. Power is still V * I, but all is about calculating the average power.
And, pretty sure there is software, that is capable of transforming a picture into a vector form. Or calculations can be done directly from a bitmap form as well, but better if it were a bit normalized, like lines made to a single pixel. But all that is a too high tech for me, i stick to gschem, and do it manually. ;)
Back in the "good old days" we would tape some tracing paper on the scope screen, transfer the scopetrace with a pencil, then cut out the waveform areas carefully with scissors and then weigh them on an analytical balance. This method can be surprisingly accurate if you do a little calibration testing beforehand.
This is not an easy task, to take an image, and transform it into curve, which then can be used for calculations. I tried to find a software which transforms an image into such curve, i couldn't find. I tried to transform the picture in gimp, the difference of gaussians, etc, give an outline of the trace, two lines, but none are one pixel thick, and it is impossible to eliminate all the background dots. Thus such image cannot be used for calculations. So still it has to be done manually. Like load the image to gimp, then create a transparent layer, and draw to it one pixel dots. Then save that layer as xpm, which then can be converted to a table of numbers, and then some curve fitting program can be applied to it. There are many these. This method can provide very accurate results, and very nice graphs, but it's quite a work.
So i still stick to this manual drawing with gschem, mostly quite rough approximation is enough. Or when one wants to do it better, one may do it with inkscape or such, where i think too it is possible to add a transparent layer, and save it hopefully in some very simple vector graphics format, which then can be used for calculations, or then as a data for curve fitting.
Now does anyone understand what i'm talking about?
Quote from: ayeaye on February 03, 2016, 09:49:44 AM
This is not an easy task, to take an image, and transform it into curve, which then can be used for calculations. I tried to find a software which transforms an image into such curve, i couldn't find. I tried to transform the picture in gimp, the difference of gaussians, etc, give an outline of the trace, two lines, but none are one pixel thick, and it is impossible to eliminate all the background dots. Thus such image cannot be used for calculations. So still it has to be done manually. Like load the image to gimp, then create a transparent layer, and draw to it one pixel dots. Then save that layer as xpm, which then can be converted to a table of numbers, and then some curve fitting program can be applied to it. There are many these. This method can provide very accurate results, and very nice graphs, but it's quite a work.
So i still stick to this manual drawing with gschem, mostly quite rough approximation is enough. Or when one wants to do it better, one may do it with inkscape or such, where i think too it is possible to add a transparent layer, and save it hopefully in some very simple vector graphics format, which then can be used for calculations, or then as a data for curve fitting.
Now does anyone understand what i'm talking about?
I certainly do. Back in the "Ainslie" day, I demonstrated how to do this process manually from a good photo of an oscilloscope trace. It is very tedious, takes about 4 hours to process a single image that way. But the results are accurate enough to be able to make valid conclusions.
I also used another technique to determine areas under a curve using pixel counting.
Now, of course, thanks to the generous donations of some forum members, I have an oscilloscope that does this math integration automatically for me.
I got this scope (UNI-T UTD2102CM):
https://www.reichelt.de/Oszilloskope-Spektrumanalyser/UTD-2102-CM/3/index.html?ACTION=3&GROUPID=4044&ARTICLE=123971 (https://www.reichelt.de/Oszilloskope-Spektrumanalyser/UTD-2102-CM/3/index.html?ACTION=3&GROUPID=4044&ARTICLE=123971)
Is this a good scope?
I would appreciate comments from the experts.
I bought it mainly because it was easily available in my part of the world. The price measured against it's capabilities was reasonable. And it is totally modern and can also be connected to the PC via USB. So, it is a fully functional stand alone scope or it can be handled like a PC-scope with a program running on a PC.
It can also store images on a USB-stick. Funny enough, the capacity of the USB-stick should not be more than 8 GB, otherwise the scope behaves strangely when trying to store an image file on it. It seems to be the supported file system.
One can argue, that the knobs and keys are not as rugged as on highly priced scopes (e.g. from TEKTRONIX).
When I looked (about three years ago), a very good scope would have costed EUR 1500.-- and more.
And yes, it is a very steep learning curve to use a scope properly. But the modern digital scopes are more forgiving than the older analogue ones. Specially the storage capabilities are very helpful. Also the mathematical functions help a lot.
The scope becomes outdated if looking at fast computing equipment. Even microprocessors are running now beyond 1 GHz. One needs 32 channel logic analysers or mixed signal scopes (12 GHz sampling rate) to see what is happening on a 3 GHz bus:
https://en.wikipedia.org/wiki/Logic_analyzer (https://en.wikipedia.org/wiki/Logic_analyzer)
Greetings, Conrad
Quote from: TinselKoala on February 03, 2016, 02:17:40 AM
Back in the "good old days" we would tape some tracing paper on the scope screen, transfer the scopetrace with a pencil, then cut out the waveform areas carefully with scissors and then weigh them on an analytical balance. This method can be surprisingly accurate if you do a little calibration testing beforehand.
Its a bit Barney Rubble, TK. Try a planimeter. Somewhere, there is a DIY planimeter page.
I had a 200Mhz Tektronix 475 about 20 years ago I left back in Aus. Looking to buy a scope and the 475's seem to be selling ~ $300 US on ebay without probes and that seems reasonable . Is anyone still using these, there seems to be a lot of them on the market but I didn't want to buy something that fails 2 weeks later, overheats, knobs break etc. Anything to look out for when buying one, any models, years to stay away from. Was thinking a 475 (200MHz, 2mV/div) or 475A (250MHz, 5mV/div).
The thread about how to measure power with analog oscilloscope is now there http://overunity.com/16911/measuring-power-with-analog-oscilloscope/#.WAFXS7Np_iY . For using analog oscilloscope for overunity experiments, it is absolutely essential to use some method to measure power with these oscilloscopes, no matter what are the shapes of the signals. One may say that doing it in any other way than pixel counting, is "not professional" or whatever, but the same transforms of the picture of the oscilloscope screen have to be done also for pixel counting. So if one thinks that it necessarily has to be done by pixel counting, then please add to that thread the details of how to do it by pixel counting.
Just to give some idea, the cheapest dso oscilloscopes, microcontrollers as oscilloscopes, or sound card as an oscilloscope, can be used for frequencies less than 10 khz maybe, but more than that, and the cheapest option i think is an old analog oscilloscope. But higher frequencies are desirable, as they provide more induction, and this likely matters for overunity. But these sound card and cheapest dso oscilloscopes. Some advanced electronics guys certainly say that they are just toys and rubbish. Because in their mind oscilloscope is an instrument that should provide precise results in all cases and all frequencies. Right of course, and thinking so, the cheap dso oscilloscopes, sound card oscilloscopes, etc, don't qualify.
But for these who wants to do it the cheapest, the thinking is different, and they can still be used. The best when using these cheapest devices, i can figure, is to use them when the results can be compared with the results measured with a more advanced instruments. Then it can be estimated how well these devices fit for the purpose. Thus they can be used for example for replicating experiments. In some cases they may replicate the results, and a similar measurements, well enough.