WTB: Oscilloscope

[tsteele93]

Argh, went to get a link and my iPad wiped all my text. Ok, try again...

Your scope looks very good, but I was hoping to spend closer to $300. My problem is that I don't know which bells and whistles are important.

I've noticed that many of them don't come with probes and cables, I'm sure those aren't cheap!

I am mainly looking to be able to measure ripple on drivers and I am also trying to fix a pair of Yamaha YST-SW800 subwoofers. I just ran through the first one and found a shorted power transistor, but the service manual calls for an o-scope for the next round of testing so I would like to be able to do something like that as well.

I honestly don't know how important calibration is on these scopes. I know it is important for them to be accurate, but I don't know how likely they are to drift from accurate and how often they are far enough off to matter. I guess what I am trying to say is, "if you buy an uncalibrated unit, is it likely to be way off and useless - or are they pretty bulletproof and likely to be fine?"

I found this one but I don't know anything about the Tek models to know what is a good one and which ones to avoid. The only things that seem obvious to me is more MHz seems like a good thing and more channels is clearly going to,cost more but I don't know why I would need four channels. Also, storage is going to cost more, but again I don't know what that actually means to me in the real world.

Thanks for any tips.

Here is the other one that looked good...

Tektronix 465 Oscilloscope - Late Model - Calibrated | eBay

 

[grenadier]

It's really a crapshoot. I've come across scopes which had a timebases 1ms off and ones that have had a 50mV attenuation, (that's .5V when set to 10x). I've also come across ones which were in all areas, completely perfect. As far as tek scopes go, they're all good. I stay away from the CRT ones though; they need to be re-calibrated often and the interfaces are generally a pain in the ass. Plus they're clunky. Analog CRT scopes are... a thing of the past to say the least.


For most things 2 channels is good. Four only becomes useful when working on a full bridge of some sort.


Storage is what lets you capture transient waveforms; things that should not be there, but appear randomly. Say a bridge explodes when you turn the amp on; a storage scope would let you see the pulse responsible.


Features I'd consider important are...

Autoset. It's the miracle button.
Dual timebase.
Automatic measurements. Have fun calculating RMS without it!
Storage and Averaging.
Triggered sweep (obviously!)

 

[tsteele93]

Triggered sweep (obviously!)

LOL! I have no idea what that is or why it is important! You can see why I am still aiming for basic!

Ok, I'm reading...

Wikipedia. Is the best thing ever. Anyone, in the world, can write anything they want about any subject. So you know you are getting the best possible information.

 

[tsteele93]

Another question... What about PC based oscilloscopes?

Pico oscilloscope range - compare oscilloscope specifications and prices

PicoScope handheld oscilloscope: a scope, spectrum analyzer and meter all in a handheld instrument

These look really interesting but I don't know if they are any good or not.

 

[bobhaha]

PC based are good if you like inaccurate data.

This has got mixed reviews...

OWON Portable Digital Oscilloscope 25MHz PDS5022S 60 Days Exchange or Money Back | eBay

Mostly good reviews, but its littered with fanboys complaining about it. For me, I think its worth the buy.... but I'm no expert.

-Adrian

 

[tsteele93]

Is 25Mhz enough? I don't know why, but I was under the impression that 25Mhz is borderline for anything but audio. Maybe I got bad info or misunderstood something?

 

[Sigurthr]

25MHz means maximum signal that can be cleanly displayed would be 2.5MHz which is below most radio / RF bands so it would be good for audio and most power electronics (IGBTs don't like very fast speeds) but would be useless for any highspeed data or digital or common RF work.

60MHz is the commonly accepted "minimum" these days, it used to be 20MHz back in the 80s. Generally people reccommend if you're going to outlay the cash for one, get it >100MHz.

 

[grenadier]

25MHz means maximum signal that can be cleanly displayed would be 2.5MHz which is below most radio / RF bands so it would be good for audio and most power electronics (IGBTs don't like very fast speeds) but would be useless for any highspeed data or digital or common RF work.

60MHz is the commonly accepted "minimum" these days, it used to be 20MHz back in the 80s. Generally people reccommend if you're going to outlay the cash for one, get it >100MHz.

On an analog scope, yes, but on a tek DSO 60MHz means 60MHz.

 

[532 with Envy]

It has been suggested to me that I get an oscilloscope if I want to continue in electronics, but I have had many of the same questions that are being asked here.

I just found this on fleebay and also a review of the product. Perhaps someone with more experience could say something. Personally I would like a new product so I don't have to worry about learning to fix it.

http://www.ebay.com/itm/261014119419?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649#ht_5236wt_1396

 

[grenadier]

I agree with bobhaha, PC based scopes are crap.


@tsteele, Triggered sweep is what keeps the waveform stable on the scope. Howard Vollum invented it, then founded a company called tektronix to produce his scopes. Before then, the waveform drifted across the screen.

OWON is like Rigol; an eastern company trying to make a dent in the american market. Both are okay, but generally the UI's suck. Kind of like using a 'dumbphone' compared to an android.

The one you linked is only 500MSa/sec. That means it samples at 500Mhz, which would give you 50 samples on a 10MHz wave. Or 10 on a 50MHz wave. Tek usually does 1GSa/sec, which is twice as good. Using the 'average' function can artificially increase the bandwidth though, and you'll see a better representation of the wav

 

[tsteele93]

I'm guessing that arduino based is a waste of time as well...

AVR DSO150 Digital Storage Oscilloscope mini +USB cable | eBay

Are there any OWON or Rigol scopes that are decent? I'd love to get a nice Tek, but I would also like to have enough money left over to buy things to test.

I guess the big question is what do you need vs what would you like to have?

That picture you posted of the 60Mhz Tek made me drool, but I can only imagine what it costs...

 

[grenadier]

I'm guessing that arduino based is a waste of time as well...

AVR DSO150 Digital Storage Oscilloscope mini +USB cable | eBay

Are there any OWON or Rigol scopes that are decent? I'd love to get a nice Tek, but I would also like to have enough money left over to buy things to test.

I guess the big question is what do you need vs what would you like to have?

That picture you posted of the 60Mhz Tek made me drool, but I can only imagine what it costs...

That 60MHz one is the one I'm selling in my other thread. If you want something to drool over, check out this baby. mso4104 - Google Search

There are decent rigol scopes, but they're about the same price as a used tek.

For me, price doesn't so much matter so long as it's a quality product. I've burnt through many extech/craftsman/elcheapo DMMs that I bit the bullet and spent $130 on a nice fluke. Sure 'brand name' products like that are a bit more, but the companies that produce the products can then afford better engineers, and better QC.

...kind of like choosing between a sears tractor and forking out the extra cash for a john deere. It's well worth it for a tool that'll last 15 more years.




Sent from my Motorola Triumph.

 

[tsteele93]

That 60MHz one is the one I'm selling in my other thread. If you want something to drool over, check out this baby. mso4104 - Google Search

There are decent rigol scopes, but they're about the same price as a used tek.

For me, price doesn't so much matter so long as it's a quality product. I've burnt through many extech/craftsman/elcheapo DMMs that I bit the bullet and spent $130 on a nice fluke. Sure 'brand name' products like that are a bit more, but the companies that produce the products can then afford better engineers, and better QC.

...kind of like choosing between a sears tractor and forking out the extra cash for a john deere. It's well worth it for a tool that'll last 15 years.

I tend to agree with that kind of thinking. Kind of a "we're too poor to buy cheap stuff" logic. But sometimes there is "expensive" vs "good enough." Especially for a hobbyist. I don't need an oscope at all really. I want one, and I could find use for one, but I don't need it.

So I'm thinking that if there is a less expensive model that is good enough, I'd like to go that route. I don't want cheap, I want inexpensive.

I was hoping that maybe one of the decent 100mhz models out there in the <$400 range might also be good. You have been a big help! I love this forum, no matter what you are doing there is someone with the skills and knowledge to help!

P.S. I just ordered this book How to Diagnose and Fix Everything Electronic, Michael Geier for $9 kindle edition and I'm already 70 pages in! It is really good and the author has already explained a lot about oscilloscopes and I haven't even hit the chapter that goes into detail on them. I highly recommend it to anyone thinking about an oscilloscope!

Also, I found this site for good info on pricing of used Tektronix scopes:

This is a compendium of some of the Vintage Tektronix equipment that has been sold on e-Bay with their sale prices.

 

[Sigurthr]

I've heard good things about certain Rigols, where as others have not received such praise. But, as Grenadier said; the ones usually praised are expensive most of the time. There's one that the EEVBlog raves on about all the time which iirc is moderately priced, but he's the only one I've heard praising it, so I'm not sure if it is worth jumping on or not.