real word reasons to use an oscilloscope as a real tool?

[cobbler]

Been trying to wrap my head around oscilloscopes- it is finally starting to make sense thank God. The main thing that was hard to understand is WHEN to use an oscilloscope!     At first I thought it was just good to have because they look cool and girls go crazy over guys with them! 

Please correct me where I am wrong.

Oscilloscopes simply help us LOOK at a signal. No matter fancy they are, no matter how many buttons and functions, the basic principle is always the same- we are looking at a signal and its ADVANCED characteristics/attributes. But why would we watch signals when we can watch TV instead?

For most electronic enthusiasts using modern components, doing everyday troubleshooting/repair 99% of the time an oscilloscope is NOT going to help as much as common sense and a multimeter.

Oscilloscopes are extremely valuable for SERIOUS circuit designers to make sure their design is working exactly as expected. In other words, doing QA, testing, and troubleshooting.

When a SERIOUS designer is making sure their work is professional, they often have to have multiple scopes sensing different part of the circuit simultaneously to visually see that everything is "working as designed". The more complex the systems get... the chance for errors is higher... thus the need for doing extensive testing with scopes.

A beginner should learn to use a scope on simple systems just to see how waveforms look. By starting to learn how to use the scope dials and triggers to quickly "lock on" the signal, we get better at using the scope and discovering how they can help us as we learn.

The more often beginners look at the scope waveforms and their characteristics... the more we start to understand signals, because many people are visual.

Professionals/advanced people who are more mathematically inclined can use the math functions of a scope to do all kinds of advanced tests and comparisons.

Modern scopes with storage capability can be very useful for finding random glitches by sensing a signal for a long time and looking for random glitches in the signal by parsing the stored data.-For digital data being transmitted, looking carefully at the bytes, ACKS, etc help ensure signal /packet integrity.

For snooping/groping/reverse engineering a digital signal, rough packet capture can done with modern scopes, although there are sometimes better tools for this like dedicated packet sniffers.Are there any other times when an oscilloscope should be used over any other tool?

Enthusiasts working with older equipment can more often turn to an oscilloscope to get granular ability to find signal issues, this is useful when replacement parts are hard to get.

Professionals repairing very high end equipment can do a very thorough test of every component in the system to make sure it is high quality workmanship.


I know the value of being able to troubleshoot, I am a programmer. Troubleshooting is everything! If you can share specific circuit examples of when using a scope is the best tool to troubleshoot it will greatly help beginners, it is hard to find practical tutorials/examples for beginners.


Thx

[ataradov]

But why would we watch signals when we can watch TV instead?

I'm quite literally laughing out loud. Never looked at the problem from this point of view

I've also never tried to watch a scope for entertainment value.

[Psi]

The vast majority of time i use my scope for MCU coding/debugging, to check all the i/o is doing what i coded.
Sometimes i toggle an output at a specific point in the code to see when that's happening with reference to external signals

[vk6zgo]

"For most electronic enthusiasts, doing everyday troubleshooting/repair 99% of the time an oscilloscope is NOT going to help as much as common sense and a multimeter."

Nope!!
Many years ago,I was troubleshooting a piece of equipment----------looking at waveforms,then using a Multimeter to check the dc rails,etc.

My Boss came past & said:-
" You don't need to do that--------it's quicker to just leave the 'scope dc coupled  & use it for everything!"
I took that to heart.

Fault finding a unit,I check the dc rails with the Oscilloscope,(in passing checking for hum or any other perturbation),then look at signal waveforms,check dc voltages on various devices,& so on.
You don't need a voltage readout on the 'scope,just set the v/div to a convenient value,& count divisions.

DMMs can be fooled:-
CRT type TV sets commonly obtain voltages of around 160v for the vertical & audio output stages by an overwind on the Horizontal output transformer.
This is rectified with a "fast recovery " diode,& filtered with a single electrolytic capacitor.

On one occasion,my DMM read this supply as 120v dc,obviously a bit low,but not low enough to cause the collapsed vertical scans I was seeing.

I borrowed an old BWD "CRO" from work,& the fault was obvious------a series of totally unfiltered half wave rectified half cycles.
Obvious with  an Oscilloscope,but not to the DMM!

People fixing stuff & those designing stuff have quite different slants on 'scope usage.
Designers like to be able to verify that the device does produce the voltage waveforms & levels they anticipated.

[tautech]

"For most electronic enthusiasts, doing everyday troubleshooting/repair 99% of the time an oscilloscope is NOT going to help as much as common sense and a multimeter."

Nope!!
Many years ago,I was troubleshooting a piece of equipment----------looking at waveforms,then using a Multimeter to check the dc rails,etc.

My Boss came past & said:-
" You don't need to do that--------it's quicker to just leave the 'scope dc coupled  & use it for everything!"
I took that to heart.

Fault finding a unit,I check the dc rails with the Oscilloscope,(in passing checking for hum or any other perturbation),then look at signal waveforms,check dc voltages on various devices,& so on.
You don't need a voltage readout on the 'scope,just set the v/div to a convenient value,& count divisions.

DMMs can be fooled:-
CRT type TV sets commonly obtain voltages of around 160v for the vertical & audio output stages by an overwind on the Horizontal output transformer.
This is rectified with a "fast recovery " diode,& filtered with a single electrolytic capacitor.

On one occasion,my DMM read this supply as 120v dc,obviously a bit low,but not low enough to cause the collapsed vertical scans I was seeing.

I borrowed an old BWD "CRO" from work,& the fault was obvious------a series of totally unfiltered half wave rectified half cycles.
Obvious with  an Oscilloscope,but not to the DMM!

People fixing stuff & those designing stuff have quite different slants on 'scope usage.
Designers like to be able to verify that the device does produce the voltage waveforms & levels they anticipated.

All this ^^^^

Ponder this:
Many but not all would forgo all TE except for 1 piece....an oscilloscope, they are so versatile.

[cyr]

Oscilloscopes simply help us LOOK at a signal. No matter fancy they are, no matter how many buttons and functions, the basic principle is always the same- we are looking at a signal and its ADVANCED characteristics/attributes.

99% of the time I'd rather have a scope than a DMM if I had to choose. The scope pretty much "only" lets you look at signals, but what could possibly be more useful than that? It's not usually "advanced" characteristics you are after, but you can tell at a glance that "yep, voltage looks fine", "clock is there, seems OK", "reset pulse is long enough", "not too much ripple on the supply".

[fubar.gr]

In my opinion, not having a scope is a big stumbling block for a hobbyist.

And there's no excuse today. Oscilloscope prices have dropped significantly. For the money you'd spend on a new smartphone (that will be obsolete within the next 3 years) you can get a kickass scope that will last you until the laws of physics do not apply anymore.

And since the OP wants some real world examples:

1) I recently got a DSO138 mini oscilloscope that won't show a signal. So I fed it with a known signal and tested whether any signal reaches the mcu's ADC. There was nothing, so there got to be something wrong in the analog front end. I finally found that one of the opamps in the quad opamp package was blown.

2) Is my PWM signal driving the switching mosfet properly? Simply stick the scope probe between drain and source. If it is properly driven I should see a nice square wave with sharp edges. If it looks rounded or the voltage doesn't go to near zero when the mosfet is on, then something is wrong.

[Shock]

Sounds like the OP was making a statement rather than asking a question.

Multimeters when doing general repairs, troubleshooting, component checking, simple prototyping. As I mentioned a few days back most electronics troubleshooting is "go, no go".

The advantages in a multimeter is it's quick and takes additional measurements, resistance, current, continuity, diode, more commonly now capacitance, temperature, frequency (along with voltage). Multimeters are not perfect for glitch capture, but many have min/max/avg and logging which can help.

Oscilloscope fits in after that. Storage, Math, FFT and other DSO functions really expand on it. Then the logic analyzer when you need to see many signals at once and debug protocols. Spectrum analyzer to see the level or multiple different frequencies at once.

Pointless jumping straight into an oscilloscope if you have not learned basic theory, not saying don't buy one, but this forum is full of people who are buying one, two, three oscilloscopes and can't use them because they don't have the fundamentals down yet. I'm sure the is a ton of buyers remorse, that is if they are not completely blinded by the fever associated with gear acquisition syndrome.

That is why I think the best advice is for a beginner wait until you have some practical and theory skills down and see how you like the hobby then reward yourself first.

And there's no excuse today. Oscilloscope prices have dropped significantly. For the money you'd spend on a new smartphone (that will be obsolete within the next 3 years) you can get a kickass scope that will last you until the laws of physics do not apply anymore.

It will take a few years for the brain to catch up I think. Either that or for Dave to tell everyone they should look into a modern DSO, but that might cause general public panic and get him burned at the stake.

[vk6zgo]

Imagine if you are presented with a microphone amplifier using the first schematic on this link page.

http://circuitmodules.com/wp-content/uploads/2013/08/microphone-preamplifier-circuit-863x1024.png

The customer says:- "I built it,& it doesn't work!"

First situation-----No Oscilloscope:-
You leap into action with your DMM.
All the dc voltages look OK,so you are stuck with lifting component leads & checking them.

Second situation-------You have an Oscilloscope:-
Using the 'scope,you look at the base of Q1,while whistling in front of the mic.
Nothing seen,so you look at the mic side of C2 & see audio.
So C2 is faulty!
You check closely,& discover one of the cap's leads is broken off internally.(this really happens!)

There are alternatives:-
This is a simple circuit,& you could find the faulty capacitor by disconnecting it (among others), & finding that it doesn't have the correct capacitance,or having the lead fall off.
OR
You could inject tone from an audio generator in various places,but this would require another amplifier & speaker connected to the preamp output to make it audible.
OR
You could use a  "Signal Tracer" & probe various points as in the 'scope case.

The first alternative is going to take considerably longer than using an Oscilloscope,& the other two require additional equipment.

[AndyC_772]

Been trying to wrap my head around oscilloscopes- it is finally starting to make sense thank God. The main thing that was hard to understand is WHEN to use an oscilloscope!     At first I thought it was just good to have because they look cool and girls go crazy over guys with them! 

Please correct me where I am wrong.

If you're trying to attract girls, I'm 99% sure an oscilloscope isn't going to help you. Try a motorcycle, or a little knowledge / interest in silver jewellery.

Oscilloscopes are extremely valuable for SERIOUS circuit designers to make sure their design is working exactly as expected.

Top tip: almost everything you read about what "serious" or "professional" engineers do, that isn't actually written by a professional engineer, is false - or at best, a vague generalisation that's dumbed-down to the point of uselessness.

[Simon]

Is this guy for real ? he obviously has neber taken a TV apart from 30 years ago and found a diagram in it that showed oscilloscope waveforms to loof for on different points and even gave you a couple of alternative waveforms with a description of the problem they indicated. I could not live without a scope, it's like having eyes in your circuit.

[Galaxyrise]

For most electronic enthusiasts using modern components, doing everyday troubleshooting/repair 99% of the time an oscilloscope is NOT going to help as much as common sense and a multimeter.

This probably comes down to what you think "most electronic enthusiasts" are doing.  Are they using PWM for anything (like controlling a servo)?  Using a 555 timer? () Using opamps that might be unintentionally oscillating? Looking for power supply ripple?

I'm definitely not more advanced than an "enthusiast" and I've encountered things that I could only measure/test with my scope.  I'm also perfectly willing to believe there are enthusiasts that haven't had it come up yet.  Enthusiast is a very broad term.

[cobbler]

Thanks for all the replies. I am seriously trying to learn when is the best time to use an oscilloscope. I am not making a statement in the original post, I knew that it needed correction.


I am at early stages of learning. I am a programmer by trade and have that part down well, now I want to focus on electronics and am just starting to get my feet wet.


It is very hard to find any tutorials that show how to troubleshoot a circuit with an oscilloscope, so everybody's comments are extremely helpful.

Especially all the real world examples you've shared. please keep suggestions flowing it is really helpful for beginners.




Thank you!

[KL27x]

DMM = average voltage, diode check, continuity test, ohm meter, current. Besides current (which is simply a function of voltage measurement on a shunt resistor, which a scope can also do), the only one of those features that works on a live circuit is the voltage test. And it only shows the average voltage. It doesn't give you the slightest indication if the voltage is steady or actually a signal/wave, or if there's any ripple/noise. A DMM can't even tell you where power is being switched completely on/off where the frequency exceeds 10ish Hz. And in the world of electronics that can be exceedingly slow. It not like you can always flip a switch, measure, flip off switch and measure. Some of these switches are being cycled thousands of times per second.

This is where the oscilloscope comes into the picture. It logs voltage over time. A scope can "zoom" in/out by adjusting the timebase, to look at high speed oscillations or even be used as a logging voltmeter. It takes the one thing a DMM can do on a live circuit, and it takes it to another level of utility.

A scope is a poor replacement for a DMM and vice versa. A scope is good for nothing on unpowered circuitry. A DMM is blind to high speed voltage changes.

[Simon]

It's not a question you need to ask really. As soon as you have a problem or want to verify something you will be wishing you have a scope.

People who come from programming to electronics often underestimate what goes on outside the chip and the analogue nature of even a digital circuit.

For example, you can consider a digital signal and off/on, as a programmer it's all you need to know, but..... take a look at that "square wave" it could have ring, it has a rise and fall time, different cables will have different effects, put a fast square wave down a pair of distant conductors and look at wehat comes out of the other end, now twist those cables and see the difference.

From a coding background you may have more appreciation for something like the scope i bought today, the Rigol DS1054Z (already "converted to DS1004Z) it can decode serial busses, even to a software engineer this is a useful tool.

[xwarp]

Just like in auto mechanics, there is a tool for the job.

A spark gap will show you there is a spark,



But the spark gap tester won't tell you what the spark is doing under operating conditions, but a scope with a capacitive probe can.



Another opinion, a multimeter provides a quantative measurement where you know what the values are supposed to be, whereas a scope provides a qualitative measurement, I.E. try looking at the R.F. modulation of the final outputs of a transceiver with a multimeter and see how much information you can derive from it to determine where a fault may be.

My point, with experience and time, you will eventually be able to take a failing piece of equipment, and with it's known symptoms, be able to look at a schematic and determine which tools you will need to properly diagnose the failure.

[cobbler]

Quote from: Simon on Today at 03:11:58 AM

It's not a question you need to ask really. As soon as you have a problem or want to verify something you will be wishing you have a scope.

People who come from programming to electronics often underestimate what goes on outside the chip and the analogue nature of even a digital circuit.

For example, you can consider a digital signal and off/on, as a programmer it's all you need to know, but..... take a look at that "square wave" it could have ring, it has a rise and fall time, different cables will have different effects, put a fast square wave down a pair of distant conductors and look at wehat comes out of the other end, now twist those cables and see the difference.

From a coding background you may have more appreciation for something like the scope i bought today, the Rigol DS1054Z (already "converted to DS1004Z) it can decode serial busses, even to a software engineer this is a useful tool.

Thanks, it makes sense what you're saying. I've met programmers who were extremely book smart, but in the real world could not program there way out of a wet paper bag.  As a programmer the best skill anybody can have (imo) is being an quick troubleshooter/debugger. That is why I am so eager to see real world examples.  I ordered a scope on ebay Sunday and it is arriving today, can't wait to start learning how to put it to use.

Where is the rep button? Do I need a certain number of posts to give rep? +rep for all those that have posted. Thx

[DimitriP]

Where is the rep button? Do I need a certain number of posts to give rep? +rep for all those that have posted. Thx

Fortunately, (most of the time, except when not) this 'aint no stack exchange.

[Simon]

Thanks, it makes sense what you're saying. I've met programmers who were extremely book smart, but in the real world could not program there way out of a wet paper bag.

I had a guy that needed to turn on a relay and check that a voltage came out of the switch and if not switch it off again. The relay would just click on and off. Luckily i was thinking out of the chip and figured that he was turning the realy on and immediately (1uS later) checking for a voltage and then 1uS later not finding anything turning it off again, the relay that needs some ms to operate did not even get a look in. Could have taken hours to diagnose without a good guess at how stupid the programmer (and circuit designer) had been. In this case no scope was needed.

[mich41]

I had a guy that needed to turn on a relay and check that a voltage came out of the switch and if not switch it off again. The relay would just click on and off. Luckily i was thinking out of the chip and figured that he was turning the realy on and immediately (1uS later) checking for a voltage and then 1uS later not finding anything turning it off again, the relay that needs some ms to operate did not even get a look in. Could have taken hours to diagnose without a good guess at how stupid the programmer (and circuit designer) had been. In this case no scope was needed.

Oh, but it would be hugely useful if it was you who wrote this code believing that it's gonna work, trust me

[madires]

Last week I had an issue with a bidirectional I/O level shifter (based on a MOSFET and two resistors) and the scope literally solved the problem. While probing both sides of the level shifter it suddenly started to work when one probe was connected to the high voltage side. When I removed the probe the level shifter stopped working. Connected the probe again and the level shifter was working. Hmm, probe/scope impedance? It can't be the resistance. So I grabbed a 12pF ceramic cap, whacked it into the breadboard and the level shifter was happy. Me too, and a little bit puzzled.

[daqq]

    But why would we watch signals when we can watch TV instead?

To be fair, you can watch TV on (some) scopes...

If you can share specific circuit examples of when using a scope is the best tool to troubleshoot it will greatly help beginners, it is hard to find practical tutorials/examples for beginners.

PWM measurement for whatever you are controlling (LEDs, motors, servos, heaters...), switched power supplies, various busses (I2C, SPI, USART...), noise on the power lines, amplification... basically measuring anything that changes over time, anything fast. I cannot imagine working without an oscilloscope.

[Simon]

I made a level translator from 12 to 24V for a customer. Simple as it was I bloody well wanted to see the reults on my scope. I was for examle able to verify the maximum frequency i was happy for it to run at. And that could only be done by looking at the waveform coming out and deciding when I was no longer happy with the look of it.

[tggzzz]

Top tip: almost everything you read about what "serious" or "professional" engineers do, that isn't actually written by a professional engineer, is false - or at best, a vague generalisation that's dumbed-down to the point of uselessness.

Unfortunately too many "professional" engineers also have severely blinkered experience, maybe 20 years experience consisting of 1 years experience repeated 20 times.

These are relatively easy to spot. Look for condident assertions that don't have a clause indicating where the assertion is valid and/or invalid.

Of course, non-professional engineers and other people also make similar "global" assertions.

[tggzzz]

Where is the rep button? Do I need a certain number of posts to give rep? +rep for all those that have posted. Thx

Fortunately, (most of the time, except when not) this 'aint no stack exchange.

Amen to that. Unfortunately too many sites aim to emulate crock exhange's success.