Oscilloscopes, how many channels do you need?

[Howardlong]

As another poster stated, 2+16 on an MSO isn't a bad option

It seems like an awful lot to cram onto a screen.

(I haven't tried it though so what do I know).

I don't think I'd ever use 16 digital channels personally.

It's very rare I do. Just that that's the "standard" config for MSOs. You can turn unused channels off, you know ;-)

[MT]

MCU applications, 4 because you need 1 cha for the reference signal and 2ch's for the signals you emulate to display your functions.

[alsetalokin4017]

I have a single-channel scope that accepts 4 inputs, plus external trigger.

It's the mighty Tek RM503 Precision Low-Frequency Oscilloscope .... which I use to make mad-scientist Lissajous displays with 4 oscillators, to help warm up my room in winter. I love its blue, long-persistence phosphor and its orange graticule illumination.

The four inputs work when the scope is in X-Y mode; the horizontal and vertical amplifiers both have separate inverting and non-inverting inputs.

[KL27x]

4 analog channels works for me though, and I don't think the price of the DS1054Z can be matched by an MSO with equivalent analog capabilities.

I wish this scope had been on the market a couple years earlier. $400? Fantastic.

[alsetalokin4017]

Sure. I just wish that Rigol would straighten out the bugs in the 1054z. What is the use of a scope that does math like this:

[lewis]

29 channels is the most I've needed. 8 analogue and 21 digital spread over two MSO scopes.

[vk6zgo]

As another poster stated, 2+16 on an MSO isn't a bad option, I'd rather have that or even 2+8 than 4+0 in most circumstances. The exception is when I'm doing switch mode power supplies when even 4 analogue channels can seem limiting.

But it depends to a large extent what you do, if you don't do much digital then the digital channels will be largely superfluous.

One further thing: remember that most 2 ch scopes have a trigger input too, which in some instances can be a reasonable compromise. A one channel scope without an external trigger offers little more than a 2.5 digit DVM for practical purposes.

Edit: meant to say, two channels can do anything a four channel can do, just not at the same time. You just need to work a little harder. Remember that 4ch scopes have only become commonplace on the average bench in the past fifteen years or so.

"One further thing: remember that most 2 ch scopes have a trigger input too, which in some instances can be a reasonable compromise. A one channel scope without an external trigger offers little more than a 2.5 digit DVM for practical purposes."

I've never encountered a single channel Osciiloscope without an external trigger,even the cruddiest 10MHz analogs have them.--------not sure about the little "toy" pocket DSOs,though!

On your other point,I've fixed equipment faults using a single channel BWD 'scope with a faulty trigger circuit,which were impossible to get a handle on using a DVM/DMM.

A DMM will be sufficient for many jobs,but some really do need a 'scope.
In those cases,any 'scope,is better than none.

[motocoder]

How many channels do you need in a 'scope?

Sub-question: What do you use it for?

99% of the time, two is sufficient. However, for that 1% of the time when you need more, you'll really kick yourself for not having purchased a 4-channel scope.  Example: troubleshooting a power supply rail sequencing error. THe project actually had 8 different rails, so in this case even 4 channels wasn't enough.

[tggzzz]

As another poster stated, 2+16 on an MSO isn't a bad option

It seems like an awful lot to cram onto a screen.
I don't think I'd ever use 16 digital channels personally.

Depends on the size of the screen; it is where a USB LA + PC + HD screen are useful. IMNSHO low refresh rates for an LA are not a problem, whereas they are for a scope.

I've used 32 channels, address, data, control lines on a Z80 but that was long ago!

[tggzzz]

How many channels do you need in a 'scope?

Sub-question: What do you use it for?

99% of the time, two is sufficient. However, for that 1% of the time when you need more, you'll really kick yourself for not having purchased a 4-channel scope.  Example: troubleshooting a power supply rail sequencing error. THe project actually had 8 different rails, so in this case even 4 channels wasn't enough.

My opinion is that with scope channels the counting scheme is "one", "two", "one fewer than I need" !

[Ivan7enych]

As another poster stated, 2+16 on an MSO isn't a bad option, I'd rather have that or even 2+8 than 4+0 in most circumstances. The exception is when I'm doing switch mode power supplies when even 4 analogue channels can seem limiting.

The same thing applies to me. I have in my lab 4 channels old Tek TDS744 and 2+16 MSO Rigol 2072a. Most of the time I turn on Rigol, not Tek.
There was one time, when I really need 4 analog channels - to find a fault in an astronomy CCD camera, to look at 3 horizontal charge transfer signals + output signal...

[JoeB83]

If I were to guess, 75-80% of my work is analog.

I've had a few MSO scopes and I found myself using the digital channels, at most, 15% of the time.

I have 2 4-ch scopes and 3 2-ch scopes at home. I use the two with four channels almost all of the time. However, once in awhile, I wonder if I had more than four (analog) channels, would I be better off?

With this in mind, has anyone seen, used, or had experience with Yokogawa's 8-channel scopes? I'm VERY curious.

I'm not sure if there are others, but the model I'm interested in is the DLM4000.

(As an aside-I don't think I've seen ANYTHING about Yokogawa. Any thoughts?)

I suppose a link to the product page may be helpful. http://tmi.yokogawa.com/us/products/oscilloscopes/digital-and-mixed-signal-oscilloscopes/dlm4000-mso-series/

[jrmymllr]

How many channels do you need in a 'scope?

Sub-question: What do you use it for?

I need at least one channel, no less.

Sorry couldn't resist.

[motocoder]

How many channels do you need in a 'scope?

Sub-question: What do you use it for?

99% of the time, two is sufficient. However, for that 1% of the time when you need more, you'll really kick yourself for not having purchased a 4-channel scope.  Example: troubleshooting a power supply rail sequencing error. THe project actually had 8 different rails, so in this case even 4 channels wasn't enough.

My opinion is that with scope channels the counting scheme is "one", "two", "one fewer than I need" !

LOL, so true

[nctnico]

(As an aside-I don't think I've seen ANYTHING about Yokogawa. Any thoughts?)

I recently bought a used Yokogawa DL1740 4 channel DSO. It has many neat features like being able to display both X-Y and Y-T for 4 channels. From the top of my head I don't know any scope which can show the Y-T (normal signals) and X-Y mode at the same time.

[Howardlong]

As another poster stated, 2+16 on an MSO isn't a bad option, I'd rather have that or even 2+8 than 4+0 in most circumstances. The exception is when I'm doing switch mode power supplies when even 4 analogue channels can seem limiting.

But it depends to a large extent what you do, if you don't do much digital then the digital channels will be largely superfluous.

One further thing: remember that most 2 ch scopes have a trigger input too, which in some instances can be a reasonable compromise. A one channel scope without an external trigger offers little more than a 2.5 digit DVM for practical purposes.

Edit: meant to say, two channels can do anything a four channel can do, just not at the same time. You just need to work a little harder. Remember that 4ch scopes have only become commonplace on the average bench in the past fifteen years or so.

"One further thing: remember that most 2 ch scopes have a trigger input too, which in some instances can be a reasonable compromise. A one channel scope without an external trigger offers little more than a 2.5 digit DVM for practical purposes."

I've never encountered a single channel Osciiloscope without an external trigger,even the cruddiest 10MHz analogs have them.--------not sure about the little "toy" pocket DSOs,though!

That was almost what I was referring to. I have a Velleman HPS10 LCD scope from many years ago, single channel 10MHz, no trigger, almost useless. I think I ever used it other than to switch it on to see if it worked, I couldn't find a reason to use it. There are others, the UT-81B for example.

On your other point,I've fixed equipment faults using a single channel BWD 'scope with a faulty trigger circuit,which were impossible to get a handle on using a DVM/DMM.

A DMM will be sufficient for many jobs,but some really do need a 'scope.
In those cases,any 'scope,is better than none.

I did say "A one channel scope without an external trigger offers little more than a 2.5 digit DVM for practical purposes", so I didn't completely discount it, but I still think it'd most likely end up in a drawer gathering dust unlike a DVM or certainly a DMM. :-)

I think we agree in general, I was just trying to dissuade anyone from even considering a single channel scope without an external trigger on it.

[Howardlong]

(As an aside-I don't think I've seen ANYTHING about Yokogawa. Any thoughts?)

I recently bought a used Yokogawa DL1740 4 channel DSO. It has many neat features like being able to display both X-Y and Y-T for 4 channels. From the top of my head I don't know any scope which can show the Y-T (normal signals) and X-Y mode at the same time.

For better or for worse, the Rigol DS1000Z does this, in fact the only way to display X-Y is with Y-T at the same time, so the X-Y display is relegated to a small proportion of the screen.

[joeqsmith]

Majority of the time, one.   Frequently two.  Rarely three.  Once in a blue moon, four.   When I have needed more than four, the BW has been low enough, I could use some sort of stand alone data acquisition system.


There was an article I read many years ago (when there were no digital scopes) that talked about adding more channels to your scope.     They basically had an external box with a mux, sample and hold, divers and some logic to scan several channels at a lower frequency and then over clock them to the scope on a single channel.   

[nctnico]

There was an article I read many years ago (when there were no digital scopes) that talked about adding more channels to your scope.     They basically had an external box with a mux, sample and hold, divers and some logic to scan several channels at a lower frequency and then over clock them to the scope on a single channel.   

I think I made such a box when I was 16 or so.

[Stephan_T]

How many channels do you need in a 'scope?

My answer would be zero, ...

Sub-question: What do you use it for?

... because as an entry level hobbyist i do not really need an oscilloscope. It is more like an expensive toy for me.

By now I have only an analogue one which actually has 4 channels (two of them only 0.1 and 1 V/cm) but i did not use them. As tautech wrote in the Siglent thread:
"Horses for courses"
From a hobby point of view, the oscilloscope is not primarily a work horse. The question is not "do I really need this or that feature", but more like "how much fun is it to display things this or that way". And displaying many signals simultaneously is getting you prettier pictures.  This is what makes a four channel coloured TV more enjoyable than some other banner specs.

Edit: Oops, I forgot an important word
Lissajous figures are also something you will not really need much of an oscilloscope today, but creating them on an analogue one is like a piece of art. I can very much enjoy to watch them.

[...]
I did say "A one channel scope without an external trigger offers little more than a 2.5 digit DVM for practical purposes", [...]

Well, not that I would want to recommend buying such a scope, but I would rather disagree on that statement. My DMM is the BM257 (the same as used by Dave in many of his videos) and although one of it's features is a Crest (Peak Hold) mode, it is not able measure ripple voltages of SMPSs:
"CREST Mode Accuracy: Specified accuracy plus 150 digits for changes > 5ms in duration."
and the AC Voltage is defined as "50Hz - 400Hz"

[Cubdriver]

Not a super easy question to answer since it's so dependent on the situation.  USUALLY not more than two, but when you NEED three or four, two won't cut it.  I'm voting for four, simply because it's more versatile.  I can use only two channels on a four channel scope, but haven't yet managed to use three or four on a two channel one.

Sort of like a parachute in a plane or a life jacket in a boat - it's better to have it and not need it than the other way 'round.

-Pat

[FlyingHacker]

I like to cascade multiple scopes together (all Tek analog scopes of course). You use the gate out on one to drive the ext trigger one the next. With two or three scopes you can get a lot of channels all triggered the same (assuming the first (triggering) scope has a good analog trigger, not some digital trigger that jitters due to sampling errors). It is really nice to visualize all those channels at once.

[rx8pilot]

If I had a 24 channel scope with a 4k 30" screen, I would use it. Most of what I do is is analog, power, and digital all mixed together with fairly complex relationships. Being able to visualize the timing behavior of the whole system would be really nice. At the moment, I have a 4ch and 2ch scope +16ch logic analyzer and have to focus on sub-sections of the circuit. It all works in the end, but if I had more channels, I could sort it all out faster.

[Wuerstchenhund]

If I had a 24 channel scope with a 4k 30" screen, I would use it. Most of what I do is is analog, power, and digital all mixed together with fairly complex relationships. Being able to visualize the timing behavior of the whole system would be really nice. At the moment, I have a 4ch and 2ch scope +16ch logic analyzer and have to focus on sub-sections of the circuit. It all works in the end, but if I had more channels, I could sort it all out faster.

Why don't you get one an 8-channel scopes then?

[rf-loop]

In my use what I need  and need was question.
~95% I need 1 Ch
~5% I need 2 Ch
~<<0.1% I need 3 Ch  (part of these cases can also do with 2Ch+Ext trig)
~<<0.02% I need  4Ch or 4Ch + Ext trig   (even these cases mostly can solve with 2 Ch+ext trig but need come from situation that most important part of need scope is working for money so in this case need is related to time what can use for work.)


Other case is what is nice to have IF there is time for just playing for entertainment. Then it is perhaps nice to have more some times.

THis is of course only what I use and need.

If  people ask from me what kind of scope he need then I need do lot of questions.  This is mainly possible only in live interactive talking with perhaps also some live demonstrations
Then IF my final answer is 2 channel, then after 5 year he find situation where he need 4 channel. Can he call me and tell I give wrong recommend? No he can not.
In this time his answers to my questions are different.

If you know what you do and you have enough knowledge and experience, then you know what you need. And more important, you know what you do NOT need.  Many peoples without enough experience do not know what they do not need.

If you do not know what are you doing,  then you do not know what you need.  And mostly also what you do not need.

In this case professionals who buy equipment for  designed needs are in different wagon than hobbyist who do not yet even know what he is doing now.  This is main reason why hobbyist then want buy things "what can do all" but is not good perhaps in any function.