Oscilloscope recommendation

[pdenisowski]

Wondering about good examples about four channels coming handy, I guess there will be some.

One example that immediately comes to mind is power efficiency measurements:  you would need to measure voltage and current on both the input and the output, so 4 channels would be needed.

[pdenisowski]

If only 1-channel device is available, looking first at one of the halves of CAN signal, then at the other, would be close to good enough to check if CAN signal looks right

To "properly" look at CAN, you would want to use a differential probe, and this would only consume a single scope channel.  If you look at the picture I posted above, you will see that only one of the four scope channels is being used to decode CAN.  You would only need two probes if you suspected an issue with the differential signaling itself (i.e. a physical layer, not a protocol layer issue).

But again, it's often sufficient to simply probe CAN_H or CAN_L with a "normal" single-ended probe.

[Aldo22]

But again, it's often sufficient to simply probe CAN_H or CAN_L with a "normal" single-ended probe.

The cheap DSO2000 has an option to decode CAN.
I don't understand anything about it and the associated trigger options look very complicated to me.
I don't think it makes sense to use this to decode OBDII.
I can imagine that in practice this is only useful in a very limited problem area and only with a very good understanding of the protocol.
Perhaps this is mainly intended for educational purposes.

[pdenisowski]

I can imagine that in practice this is only useful in a very limited problem area and only with a very good understanding of the protocol.

Yes, just being able to decode CAN frames isn't that useful unless you know quite a bit about CAN.

The cheap handheld OBDII-connectable analysis tools (there's one in the picture above) are a much more user-friendly way of getting practical, useful data from a CAN bus if you're just trying to repair or troubleshoot a car.

[tatel]

Wondering about good examples about four channels coming handy, I guess there will be some.

One example that immediately comes to mind is power efficiency measurements:  you would need to measure voltage and current on both the input and the output, so 4 channels would be needed.

You are right, of course. My bad: I should have said "good examples about four channels coming handy for automotive work" So far it's clear to me that, for automotive work, CAN decoding isn't strictly necessary; and that, while 1-channel oscilloscope is enough to do most of the tasks, there's at least one case when having a 2-channel oscilloscope comes handy. Then I was wondering about a case where more than 2 channels would be "needed". Since there are 4-channels automotive oscilloscopes for sale, one would think there's a motive for that.

[BillyO]

"good examples about four channels coming handy for automotive work"

While I'm not an auto tech, I have seen many automotive oscilloscopes that have 8 channels.  Like this from Hantek: https://www.hantek.com/products/detail/13170

I think Pico have them too.  Others too.

Must be a reason for it.

[themadhippy]

I have seen many automotive oscilloscopes that have 8 channels.

you'd have thought  one of the more expensive manufacturers would do a  v12  scope

[CAG]

Tons of good information, thank you! I'm continuing to research and try to educate myself before making a purchase. It seems to me the scopes advertised as automotive scopes are overpriced for the performance specs. I think you end up paying for some automated presets and simplified menus. Tools like that have always bothered me. I'm better off struggling through the learning curve with a more full featured tool. One that makes me set all the adjustments and understand what's going on. I had access to a snap on branded scope for several years. I used it successfully to do some diag work here and there. It was so heavily focused on presets and auto ranging with any custom settings buried is several layers of bs menus. Now even with that experience I'm not sure of what kind of specs I really need. I'm looking forward to having a scope with a few knobs and buttons so I can't start twisting and learning. I'm convinced I can cut my budget in half after reading all the posts here and learning some more. $400 to $475. I think that will get me something that feels like a jet fighter compared to that snapon unit. I'm really stuck on the rigol units. Trying to keep an open mind for sure but the form factor and Dave's review of the 800 series is stuck in my head. I know it's a bench scope but still very portable if need be. Mounting options are plenty. I'm still struggling to understand the relationship between bandwidth, waveforms per sec, rise time, and deep memory. Some specs seem redundant. Wouldn't sample rate mainly dictate how much resolution you could see on a given waveform? Also dictate the bandwidth the scope could be useful for? Also dictate how fast a rise time you could measure? But they are all separate specs. I'm missing something I'm sure of it. The hunt for knowledge continues! Thanks for all the advice and suggestions.

[CAG]

I can defiantly name 5+ times in recent memory where a scope would have been useful. i know exactly what i would have measured and how i would have set it up. what im not sure of are the mistakes i would have made along the way and what the results would have been. All the cars im thinking of did get fixed and customers are happy. I do think the scope could have prevented a couple comebacks and saved some time though. I have attended several classes that went over testing methods and setups using scopes but i really am better off struggling a bit with something new, maybe even failing in frustration and letting that drive me to learn what i have done wrong. i never forget lessons learned that way. I have a quality dmm, a power probe, an amp clamp.... stuff like that. Im not totally new to electrickery but its an area i need to build more skills in for sure.

[CAG]

I'm an automotive mechanic by trade. I have recently been tasked with dealing with all the more complex electrical diag work at the shop. I have limited experience with an oscilloscope.

Two questions for you:

1.  Can you give 3 to 5 specific examples of how you would use an oscilloscope on an car or truck?  By specific, I mean make/model/year and exactly what the issue is and how you would use the scope to test.

2.  Are you an IATN member?

If both answers are simply "no", then I'd recommend you buy some cheap piece of junk that you can learn with.  You don't need exceptional performance for automotive work but the mains-powered lunchbox style scopes you are considering would lead a rough life in an shop.  Battery power, handheld and reasonably durable are pretty standard requirements.  The Picoscope 2204A would be my beginners recommendation in most cases and having the laptop attached is a huge advantage IMO, but apparently you disagree.  If you had trouble using a Modis (which is what I presume you were referring to) then you have some work to do.  Just getting a signal on the screen is only the first step of effectively using a scope in your field.

1. yes
2. no, seems like google searching IATN now would be cheating...

[CAG]

looking hard at the 800. thank you for link.

[CAG]

I think you might be right. I dont see anyone else using a bench scope in an automotive environment. Im thinking of buying a rigol more in the 450 dollar range and trying it out. it wouldnt be the first time i have worked "outside the box" and been happy with the results. if im wrong ill take it home and mess with it there. i am interested in electronics repair on a small hobby type scale. im not rich by any means but at the 400 ish price range im ok with a little gamble. i think ill get my money out of it one way or another.

[CAG]

2 ch is minimum for me. i do know that much. the scope i was using for awhile was 2 ch and fairly often i wanted at least one more. there was always a work around but it cost more time and effort.

[CAG]

As i scroll to the end here it has come to my attention that I am not using the quote and reply options effectively. its getting messy. dang.

[bdunham7]

I can defiantly name 5+ times in recent memory where a scope would have been useful. i know exactly what i would have measured and how i would have set it up. what im not sure of are the mistakes i would have made along the way and what the results would have been. All the cars im thinking of did get fixed and customers are happy. I do think the scope could have prevented a couple comebacks and saved some time though. I have attended several classes that went over testing methods and setups using scopes but i really am better off struggling a bit with something new, maybe even failing in frustration and letting that drive me to learn what i have done wrong. i never forget lessons learned that way. I have a quality dmm, a power probe, an amp clamp.... stuff like that. Im not totally new to electrickery but its an area i need to build more skills in for sure.

I started using scopes in the automotive field over 30 years ago when the idea of using them for anything other than ignition was fairly uncommon.  My first scope that wasn't on a cart was a Fluke 98, which I still have today.  The first case that I remember where it saved me from a major headache is when I was given an an older Chrysler New Yorker (318 V8) for a tuneup and carb adjust/overhaul as needed.  The complaint was hard start and rough run when cold.  It was the cranking compression test that showed 3 bad valves that very quickly convinced the service manager to revise the work order.  If I had just said "I think it has a mechanical problem because it sounds uneven when cranking" I probably would have been told to just do the requested work first.  The Fluke 98 has a reasonably good array of special features that were very helpful in those days.  OBD data has improved, ECUs are smarter and I actually think there is less occasion to use a scope these days.  Setting up those specific tests can be done with a generic DSO but you'd really have to understand what you are doing. 

If you get a regular scope as you indicate, how would you use it on a road test?  One of the most useful features of a scope with a recording feature is to solve the "what fails first" problem when dealing with intermittent issues.  Perhaps I don't know the specific issues that you encounter so that's why I asked.

Some specs seem redundant. Wouldn't sample rate mainly dictate how much resolution you could see on a given waveform? Also dictate the bandwidth the scope could be useful for? Also dictate how fast a rise time you could measure? But they are all separate specs. I'm missing something I'm sure of it.

Sample rate will set an upper limit on bandwidth, but BW can be (and usually is) less than this limit due to analog circuit design and marketing.  BW and rise time are correlated but not always in a simple way.  Both are essentially irrelevant to your application.  The Fluke 98 has 20MSa/s and 5MHz BW.  Anything more than that is "enough".

I asked before -- are you a member of iATN?  If not, I'd recommend you have a look.  I see you answered 'no'.  That's the wrong answer!  Given what your goals are--immediate and future--it would be insane to ignore that valuable resource.  It's unfortunate that the waveform library isn't in the free section (it was all free two decades ago...) but you can get additional answers--and probably more relevant--to your questions in the forums.

[BillyO]

As i scroll to the end here it has come to my attention that I am not using the quote and reply options effectively. its getting messy. dang.

Just a suggestion, but if you use "quote" rather than "reply" we might better know who you are responding to.

[pdenisowski]

OBD data has improved, ECUs are smarter and I actually think there is less occasion to use a scope these days.  Setting up those specific tests can be done with a generic DSO but you'd really have to understand what you are doing.

Agree completely.  Graham Stoakes' book "Automotive Oscilloscopes: Waveform Analysis" (mentioned in an earlier post) is an interesting read as well.

If you get a regular scope as you indicate, how would you use it on a road test?  One of the most useful features of a scope with a recording feature is to solve the "what fails first" problem when dealing with intermittent issues.

Aside from powering a "normal" scope from an inverter, there are also battery powered scopes with recording / data logging features, e.g. our RTH series handheld oscilloscope.  But I do wonder if the probe connections might be a challenge during a road test (?)

[bdunham7]

Aside from powering a "normal" scope from an inverter, there are also battery powered scopes with recording / data logging features, e.g. our RTH series handheld oscilloscope.  But I do wonder if the probe connections might be a challenge during a road test (?)

The Fluke 98 and 98-II automotive-specific scopes were configured a bit differently from the rest and one big difference was that the scope is designed to almost exclusively use 1:1 connections.  The inputs not only tolerate 300V+, they can actually respond to and display those amplitudes.  This turns a probing problem into a simple wiring problem and they included a good assortment of connection methods in the original packages.

[tatel]

Since you are willing to struggle and learn with a non-automotive oscilloscope, perhaps it would be wise to get first a cheap 2 channel device.

After that, you'll probably be able to decide by yourself which jet fighter is the one right for you.

Of course I could be wise to buy that Picoscope, or perhaps the FNIRSI, or another device in the 130 bucks range, that could probably be put on sale when you are ready to upgrade. However there are even cheaper model that could quite probably do what you need

There's a quite useful thread about cheap portable oscilloscopes, so you could compare:
https://www.eevblog.com/forum/testgear/portable-oscilloscopes-list/msg5194335/#msg5194335

[aliarifat794]

Owon oscilloscopes are good.

[Aldo22]

Aside from powering a "normal" scope from an inverter,

By the way, is it safe to use inverters to power oscilloscopes?
I have generally had bad experiences with "modified sine wave" inverters, but I now have a "pure sine wave" inverter.
However, I have never dared to use it with an oscilloscope.
Are there any problems to be expected?
The output of the inverter looks like in the attachment (On a fnirsi dso-tc2). Should be OK, right?

[Aldo22]

I am answering my own question.
Yes, it works. I can't see any excessive noise at first glance.
This could be useful in certain situations, especially if you already have the inverter and a 12 volt battery.