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Old 12-14-2017, 02:05 PM   #1
Dannyx
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Question First oscilloscope thoughts

Good day folks. While I'm definitely not a pro in electronics, there have been times when I really needed/WANTED a scope, either for hobby purposes or for professional use trying to repair something. I think we can all agree a scope is one of the most sought after tools in any electronics hobbyist arsenal, but it's also one of the most expensive and hard to get. Still, I wanted to take a crack at getting something half-decent, so I hit the auction sites, since there's no way I'd even afford a new one and...not being too sure what I should look out for, other than the price for now, I found this one which looks half decent for the price IMO (it's on a local auction site so don't worry about the language). Konig os 25 d. Ok, so it's a little worse for wear but it does work and LOOKS professional ENOUGH...looks like a german product, so perhaps someone can help us out here. The price...well it's not something I'd give away as a present, but not prohibitive either, esp for a scope - one of the most expensive things in this field. To give you an idea, it costs 500 of our RON (let's make it round) which is 127.35 USD or 107.98 EUR. I could probably negotiate a bit and go even lower, which I'm all too happy to do at this point since this is the best looking one I've come across that looks alright - DIGITAL ones...just forget about it...not unless I inherit something overnight

I'm not too vexed with scopes, so I don't know what I should be looking out for, other than the frequency. I'm sure there are lots of resources out there, but I'd like some thoughts on this particular one....true, I couldn't really find much about it, but hey...perhaps someone else did and gave it a crack. Cheers guys
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Old 12-14-2017, 02:24 PM   #2
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Default Re: First oscilloscope thoughts

25MHz - run away!
it's worth maybe 1€ per MHz

you should be able to get 100MHz+ from HP or HAMEG or another big name for that on ebay.

too bad your short on cash, Rigol is doing a christmas discount on the DS1054Z,
https://www.rigol.eu/products/digita...oscopes/1000z/

Last edited by stj; 12-14-2017 at 02:27 PM..
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Old 12-14-2017, 03:04 PM   #3
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Default Re: First oscilloscope thoughts

Quote:
Originally Posted by Dannyx View Post
Good day folks. While I'm definitely not a pro in electronics, there have been times when I really needed/WANTED a scope, either for hobby purposes or for professional use trying to repair something. I think we can all agree a scope is one of the most sought after tools in any electronics hobbyist arsenal, but it's also one of the most expensive and hard to get.

I'm not too vexed with scopes, so I don't know what I should be looking out for, other than the frequency. I'm sure there are lots of resources out there, but I'd like some thoughts on this particular one....true, I couldn't really find much about it, but hey...perhaps someone else did and gave it a crack. Cheers guys
Figure out how you expect to be using the 'scope. Troubleshooting power supplies requires a different set of capabilities than troubleshooting logic circuits.

My first 'scope was a Tek 465http://w140.com/tekwiki/wiki/465 Back then (35 years ago?), it was a delight to have. Nowadays, it would be woefully inadequate for many of the situations in which it would be needed.

In addition to auction sites, consider local firms (especially schools/universities) that may be disposing of surplus equipment on a somewhat regular basis (the local university has an auction every 2-4 weeks with a wide variety of lots from maintenance vehicles to furniture to PCs to electronic test equipment). The same is true of many businesses; it's more a problem of sorting out who you need to talk to in order to find out how the kit is disposed.

I passed up a TDS540 the other day (my car was full) as I've already got two DSO's.http://w140.com/tekwiki/wiki/TDS540

Also consider the probes. They can represent a considerable cost -- esp if you are looking for high end probes. I routinely grab any probes I come across and throw them in a bag I've set aside just for this purpose. You can never have too many!

Lastly, if you will be spending much time troubleshooting high-speed logic (or, even microprocessor systems), consider a logic analyzer, instead. There, you will be looking for number of channels above all else.
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Old 12-14-2017, 03:10 PM   #4
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Default Re: First oscilloscope thoughts

I thought it'd be sh!t, that's why I wanted to check with pros first....Rigol ? HP ? Keysight ? Perhaps in like 10 years or so
While not really SHORT on cash per-se (could technically afford a top of the range one at that) it would be a very dumb move to spunk that amount of $$$ for something I'd honestly have very basic and little use for.....hey MA ! MAAA ! Look at the pretty line bouncing around
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Old 12-14-2017, 03:19 PM   #5
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Default Re: First oscilloscope thoughts

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I thought it'd be sh!t, that's why I wanted to check with pros first....Rigol ? HP ? Keysight ? Perhaps in like 10 years or so
While not really SHORT on cash per-se (could technically afford a top of the range one at that) it would be a very dumb move to spunk that amount of $$$ for something I'd honestly have very basic and little use for.....hey MA ! MAAA ! Look at the pretty line bouncing around
Note that you can usually pre-think your debugging strategy to eliminate the need for many specialized tools. I troubleshoot TV's with a voltmeter ('scope takes up too much space). Most logic I troubleshoot with just a logic probe (logic analyzer takes up too much space). Software with debug stubs and careful repurposing of useful outputs (i.e., using an indicator lamp to tell me when the code gets to point X).

Note my comment re: your beep gizmo as to how you can set the frequency of the tone with a stopwatch instead of a 'scope!
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Old 12-14-2017, 03:34 PM   #6
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Default Re: First oscilloscope thoughts

Of course I never got stuck because I didn't have a scope - I've repaired quite a few things with just my meter (not like I have any other more advanced tool ATM) The biggest issue with meters is they can't measure high speed signals to see whether some stuff works or not.
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Old 12-15-2017, 01:34 PM   #7
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Default Re: First oscilloscope thoughts

Yes a scope makes looking at lvds signals and digital more informative. I got a Hantek DSO5072P Digital Oscilloscope 2Channels 70MHz upgraded to 100mz for $180. Seems to work good. But am no expert with scopes
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Old 12-15-2017, 01:58 PM   #8
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Default Re: First oscilloscope thoughts

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Yes a scope makes looking at lvds signals and digital more informative. I got a Hantek DSO5072P Digital Oscilloscope 2Channels 70MHz upgraded to 100mz for $180. Seems to work good. But am no expert with scopes
I saw a lot of Hanteks at reasonable prices here as well and I even considered investing in one at one point myself, but after a (albeit brief) research, they were not too impressive in terms of performance....still, maybe better than the one I saw and perhaps I was a bit superficial in my searches, but as you've said, I'm no expert either, so could still be perfectly fine for an amateur.
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Old 12-15-2017, 03:37 PM   #9
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Default Re: First oscilloscope thoughts

If you only need to capture frequencies up to 20 KHz (pretty low, I know ), you can use Visual Analyzer on a spare junk laptop. Visual Analyzer is basically an oscilloscope-like piece of software that uses your computer's microphone / line input jack to analyze audio signals. It has a window to show you the shape of the waveform and also a spectrum analyzer, along with a frequency meter. It's not very accurate or very useful for measuring voltage, and you will need to make your own probe from a spare audio cable (along with a few resistors if you want to measure more than 2-3 volts, in order to prevent damage to your audio inputs). But, for troubleshooting signals in the audible range, it's just fine. Moreover, when combined with programs like Audacity, you can capture the whole signal waveform into an audio file and then replay it as many times as you need for analysis.

Again, this is a very limited tool that can capture frequencies only up to 20 KHz or less (depending on how good your audio processor is) and also not very intuitive to use if you have never used a real oscilloscope. But for some basic circuits, it can be quite useful. I remember I used this for college when I needed to make a 120 Hz square-wave generator with a 50% duty cycle. Although my multimeter has frequency counter and duty cycle counter, it was nice to be able to see the waveform in real time.

Recently, I used it to capture the signal from a Nikko remote control transmitter for an RC car as I was trying to reverse-engineer the signal of the transmitter chip. Turns out, it was just a square-wave signal with varying pulse width.

Last edited by momaka; 12-15-2017 at 03:38 PM..
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Old 12-21-2017, 08:47 AM   #10
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Default Re: First oscilloscope thoughts

Actually, how about those Hanteks someone mentioned ? I considered one of those too at some point, but like I said, all that excitement quickly died when I read they're not that great and they're mostly intended for automotive applications, I knew that....they claim frequencies of 40Mhz, which is still a bit low I guess, but still better than nothing.
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Old 12-21-2017, 09:32 AM   #11
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Default Re: First oscilloscope thoughts

you are better off with an old analog 100MHz scope from ebay, if you cant jump to a Rigol.
IMO.
too bad your not closer - i could probably locate a 100MHz+ big-name analog scope for the kind of money you were going to pay.
infact there would be enough left over for a pair of new probes.
you probably also want to get a x100 probe - for psu repair.

maybe you should ask over at eevblog forums - a lot of guys there with loads of surplus stuff.
maybe someone local can do you a deal.

Last edited by stj; 12-21-2017 at 09:33 AM..
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Old 12-21-2017, 10:58 AM   #12
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Default Re: First oscilloscope thoughts

I HAVE seen analog scopes locally, but they're either too old to be useful anymore (although beggars can't be choosers I suppose) or too expensive or are defective. I haven't even used a scope before, so I'm not entirely sure I'd be able to fix one and even then, they're STILL not very cheap despite being broken.

I figured my best option is to just wait and save my cash (something like "scope fund" ) until I can afford to spend some decent cash on a good scope rather than spend less than that (though still not little) on a mediocre thing. Who knows, I might even strike a good deal somewhere Just today I saw something "interesting" for the equivalent of around 250$, which is...much, at least for me, your average working-class Joe, but in the long run, I WOULD be willing to spend it, especially since I seem to run into the issue more and more. For instance, for the past few days I've been messing around with a junk TV which has no backlight and I have no way of telling if the boost converter IC is even working...a scope would make that a breeze.

I gave ebay a shot a while ago for some other tool, but what kills it is the shipping, since scopes are big and heavy and nobody in the right mind would be willing to offer free shipping for one (which would essentially mean paying the shipping for you)....
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Old 12-21-2017, 12:19 PM   #13
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Default Re: First oscilloscope thoughts

do you have the equivalent of car-boot sales there?
where people sell loads of stuff in a field or car-park?

if yes - keep an eye on them!!
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Old 12-21-2017, 12:44 PM   #14
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Default Re: First oscilloscope thoughts

We have something similar...it's more like a flea market where people gather to sell all sorts of stuff/junk, from cars to clothes and electronics. There are no rules and no hierarchy. ANYTHING goes. Only problem is that the chances of finding a functional device here are rather slim, much less so something so professional and "niche" as a scope. I've never personally been to one of these "swap meets", but my father frequents the hell out of it and he mostly reports junk being sold. Many people don't even know what they're selling, which I guess could be the perfect opportunity to break it big, but like I said: VERY unlikely to find something useful and functional here, though I WILL tell my pop to be on the lookout for anything that looks like a scope
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Old 12-21-2017, 01:04 PM   #15
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Default Re: First oscilloscope thoughts

that's it, you sometimes get people selling stuff they dont understand - workshop clearout or dead relative type situation.

good place for games consoles, retro stuff or test gear - if you keep your eyes open.
i got a 3-trace 100MHz japanese scope for £25 at one once!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
same seller had components in factory packaging,
paid £3 for a box with 5000 low voltdrop 250ma diodes in it!!
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Old 12-21-2017, 01:05 PM   #16
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Default Re: First oscilloscope thoughts

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I've never personally been to one of these "swap meets", but my father frequents the hell out of it and he mostly reports junk being sold. Many people don't even know what they're selling, which I guess could be the perfect opportunity to break it big, but like I said: VERY unlikely to find something useful and functional here, though I WILL tell my pop to be on the lookout for anything that looks like a scope
There's a guy, here, who buys things that we know are defective -- but "look" good (cosmetically). As there is no practical way for a potential buyer to test the item at the swap meet (lack of power, signal, etc.), the buyer buys it on faith. Then, gets home to discover he's bought someone else's TRASH.

For most buyers, this is a losing proposition (they don't have the skills to be able to repair even simple problems).

Check local universities and businesses. Many have formal procedures in place for disposing of surplus equipment. Often, it boils down to simply knowing their process and the name of the proper contact person.
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Old 12-21-2017, 01:20 PM   #17
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Default Re: First oscilloscope thoughts

Digital Logic Analyzer - FREE
ElmüSoft is a freeware app that uses a parallel port to manage TTL logic for up to 17 channels. If necessary you can install a cheap parallel port in your computer to suit. Use level shifting to manage non-TTL signals.

I have used this for several projects, 3-4 channels up to about 50MHz on a P4 machine.. It takes some practice and experience to get good results, but certainly worth a try. And you can't beat the price.

Diagrams and explanations here:
https://www.codeproject.com/Articles...Logic-Analyzer
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Old 12-21-2017, 01:24 PM   #18
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Default Re: First oscilloscope thoughts

Try this to help you find a good value scope.
https://www.youtube.com/watch?v=lZfbo-2sd1A
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Old 12-21-2017, 04:11 PM   #19
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Default Re: First oscilloscope thoughts

about boot sales,
round here a lot of regular sellers now have an invertor to prove stuff works.
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Old 12-22-2017, 01:35 AM   #20
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Default Re: First oscilloscope thoughts

How bad is the jitter on the parallel port logic analyzer?
I've never *really* needed a logic analyzer yet though there where times where it would have been nice.
Tempted to try it, or at least somehow get a Linux version going for the heck of it...
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