what an oscilloscope recommended for a woman passionate about electronics?

[CharlotteSwiss]

Look at the 7th harmonic, it has too much amplitude for an actual square wave.  That's because your calibration signal has a very slow rise time, nowhere near 0 nanoseconds but much closer to several microseconds.  You can have the scope tell you the rise time.  That's part of the magic of the modern DSO.

oh yes, I had noticed that harmonica that did not reduce the amplitude as it should have, now I understand: the formula f / 3, f / 5 etc .. is valid if, however, the square wave has practically zero rise times.
I just checked the rise time of the compensation wave, it is 1.02us, so 1020 ns ...

A 100 MHz scope doesn't suddenly quit displaying a trace at 101 MHz.  In fact, the Rigol DS1054Z, after being unlocked for 100 MHz, has a bandwidth of 130 MHz, give or take.  The thing is, we need to understand that the 'bandwidth' is considered to be a point where the signal has lost 3dB or the value displayed is 0.707 times the actual value.  If I stuff a 130 MHz 1V signal into the Rigol, the display will read about 0.707V.  The displayed voltage has been declining from around 100 MHz and will continue to decline down to essentially 0V at some really high frequency.  That's what the Bode' plot is all about.  Attenuation versus frequency.  But the signal still shows up!  The problem is that the high frequency components of a square wave disappear and the square wave ultimately displays as a normal sine wave because the harmonics are all attenuated.  What you see on a scope is just a squiggly line.  Interpreting it takes knowledge about the actual nature of the signal.

Here is a typical Bode' plot of an RC filter and the front end of a scope works exactly the same way.  I have a cursor at the -3dB frequency where we also expect a 45 degree phase shift

https://www.eevblog.com/forum/testgear/starter-scope/msg2969998/#msg2969998

There are some more experiments a few replies down.  I was having fun with my Analog Discovery 2 that day!

ok I understand: let's take my siglent as an example, it has a declared band of 200Mhz.
If I go to measure a signal at 200Mhz, the signal will be attenuated and if for example the signal has a 1v Vpp, the oscilloscope will measure it slightly lower in amplitude ... and the more I want to measure signals with even higher frequencies, the more amplitude represented will decrease.
Do we have a chance to know, having a band of 200Mhz, up to what frequency I can measure a signal so that the oscilloscope represents me the total amplitude of the signal?

I saw that topic, it seems interesting to me to play with Analog Discovery 2

thanks 

[CharlotteSwiss]

The scope discussion was settled when you made an excellent purchase.  The signal generator hasn't really gotten serious and that's fine.  In fact, it's for the best because the more recent discussions have centered on the capabilities of the modern AWG.  I'm using the Siglent SDG2082X but I think the less expensive SDG1032X will do the same thing but with a lower frequency range.

The things we're talking about in this thread go well beyond what the average hobbyist will need to know.  We're covered a lot of ground!

What we need to do is get Tautech to discuss the differences between the SDG1032X and the SDG2082X other than frequency.  It's important to realize that the maximum frequency is also the highest harmonic frequency that can be included in an arbitrary waveform.  In other words, a square wave created by adding harmonics to a fundamental will have an upper limit on the frequency of the harmonic.   If we really want a fast rising square wave, an AWG isn't the way to get one.  There are several projects here on eevblog discussing such a tool and it is usually made with a high speed logic gate.  We're talking sub nanosecond rise times.

My brief reading of the SDG1032X User Manual didn't turn up any obvious differences in features between it and the SDG2082X (other than upper limit on frequency) and it's features that matter.  The SDG1032X may be just right.  I suppose there are reviews over in the Test Equipment forum.

thanks for the rstofer analysis: we understood that 1032 might be fine for me, it is still a fairly expensive purchase; we must also calculate that it would have a reduced use compared to the oscilloscope, and perhaps for a beginner it could be perhaps even too expensive. However, I see that there are not many products at a much lower cost, if not the usual fy6900 ...
I should start to understand: Will it have a lot of use in my troubleshooting repairs?
It would also be necessary to understand with what amplitude it can come out with the signal, and if it is sufficient to test parts of the circuit: obviously enough within 15v ..

[CharlotteSwiss]

SDG2000X models vs SDG1000X models.
16 bit, faster sampling engine, more waveform memory and touch display for SDG2000X. Touch is occasionally handy but you can live without it.
SDG1000X, square wave to max frequency whereas SDG2kX top out at 25 MHz for square wave.

That's about all the key differences as they have the same waveform suite and other functionality.
For the hobbyist SDG1032X is a fine choice and our best seller and was my main AWG until upgrading.

I spoilt myself and got a SDG6202X a while back after grumbling at the price for a year or 2 but I needed one for a demo model anyways. 200 MHz sine, 80 MHz square wave and 1ns risetime is very nice and so it should be for the price. 

thanks for the specs; we have already discussed previously that there would be the cheaper 800 series it seems to me, but maybe it will have some important limitations.
1032 is nice, but it is not given as a gift 

[CharlotteSwiss]

When these discussions turn technical, it's nice to have the equipment required to put together an experiment reinforcing the learning.  My learning...

I agree, but first as mentioned I have to study the oscilloscope manual, I don't like having two things to study in the field, it confuses my ideas.
I will do the most sophisticated experiments when I also have the generator, but then I can concentrate only on that.
I'm from the parts of page 140/150, as soon as I rearrange the ideas and finish the math chapter, I think it will be easy to study until the end of the manual without major obstacles (I hope)
thanks rstofer

[rstofer]

thanks for the rstofer analysis: we understood that 1032 might be fine for me, it is still a fairly expensive purchase; we must also calculate that it would have a reduced use compared to the oscilloscope, and perhaps for a beginner it could be perhaps even too expensive. However, I see that there are not many products at a much lower cost, if not the usual fy6900 ...
I should start to understand: Will it have a lot of use in my troubleshooting repairs?
It would also be necessary to understand with what amplitude it can come out with the signal, and if it is sufficient to test parts of the circuit: obviously enough within 15v ..

I managed to get along without an AWG for more than 60 years, nearly 50 since I finished undergrad.  I always played with digital and all I needed was a decent square wave of an appropriate frequency.  It's only since I started hanging out here that I have moved toward more 'educational' topics.

Then again, I haven't had a bench power supply either.  5V fixed supplies were adequate and my robotics projects have always been battery powered.

I bought a couple of used bench DMMs from eBay just because they could sit on a shelf above the bench, out of the workspace.  Handheld meters, of which I have several, seem to get in the way.  I still use the handhelds far more often...

We have spent days talking about FFT but I have used it exactly once in my entire career.  Do I really care is the DSO can display it?  Probably not!  Of course, since modern DSOs already have it, I might as well learn how it works.  I still don't have a use for the FFT and likely never will other than 'learning' topics around here.

Troubleshooting?  Troubleshooting what?  Most manufactured gadgets defy repair.  Among other things, you probably can't even get the custom chips.  Even some Tektronix scopes become impossible to repair.  I must be in a different place because I can't imagine troubleshooting anything other than a project I built.  Is a signal generator useful?  Not to me!  Everything I do is digital, whether Arduino, Raspberry Pi, ARM or FPGAs.  I need a scope, I probably need a logic analyzer and that's about it.

Truth told, I don't need much of the bench equipment I have.  The Analog Discovery 2 can handle everything I do.  The Digital Discovery 2 is probably a better tool for pure digital but it doesn't have a scope feature.  Nevertheless, I have both and I use them more than any of my bench equipment.  Cheaper too!

I'm also certain that there are others around here who spend more time with audio or analog and less with digital.  Electronics covers a pretty wide field and there's room for everybody.  Their needs will differ, mine are fairly minimal.

Being retired leaves me more time to play with electronics so I added some tools over the last few years.  I have enough now to do just about anything I can imagine.

For giggles, I redid the recent FFT project using my AD2:

[rstofer]

w2aew (Alan Wolke) has a bunch of YouTube videos on simple circuits using transistors or op amps.  This is where I use my AWG the most - following along with what he is teaching.  I highly recommend his videos.  Dave has some "Fundamental Friday" videos that go into theory as well and the Op Amp video is excellent.  I tend to like the tutorial videos.

Here is a link to Alan's channel with the videos sorted by ascending date.  I tend to skip those related to ham radio but #65,66 and 67 jump right out.
https://www.youtube.com/user/w2aew/videos?view=0&sort=da&flow=grid

Dave's op amp introduction:


In the first minute Dave talks about why Op Amps were invented: analog computing, my favorite topic.  Integration, differentiation and arithmetic can all be performed with an op amp.  A multiplier is a little more complex but has been around for a long time.  In the old days it was based on a motorized variac.

Analog computing still exists.

https://en.wikipedia.org/wiki/Analog_computer

[CharlotteSwiss]

thanks for the rstofer analysis: we understood that 1032 might be fine for me, it is still a fairly expensive purchase; we must also calculate that it would have a reduced use compared to the oscilloscope, and perhaps for a beginner it could be perhaps even too expensive. However, I see that there are not many products at a much lower cost, if not the usual fy6900 ...
I should start to understand: Will it have a lot of use in my troubleshooting repairs?
It would also be necessary to understand with what amplitude it can come out with the signal, and if it is sufficient to test parts of the circuit: obviously enough within 15v ..

I managed to get along without an AWG for more than 60 years, nearly 50 since I finished undergrad.  I always played with digital and all I needed was a decent square wave of an appropriate frequency.  It's only since I started hanging out here that I have moved toward more 'educational' topics.

Then again, I haven't had a bench power supply either.  5V fixed supplies were adequate and my robotics projects have always been battery powered.

I bought a couple of used bench DMMs from eBay just because they could sit on a shelf above the bench, out of the workspace.  Handheld meters, of which I have several, seem to get in the way.  I still use the handhelds far more often...

We have spent days talking about FFT but I have used it exactly once in my entire career.  Do I really care is the DSO can display it?  Probably not!  Of course, since modern DSOs already have it, I might as well learn how it works.  I still don't have a use for the FFT and likely never will other than 'learning' topics around here.

Troubleshooting?  Troubleshooting what?  Most manufactured gadgets defy repair.  Among other things, you probably can't even get the custom chips.  Even some Tektronix scopes become impossible to repair.  I must be in a different place because I can't imagine troubleshooting anything other than a project I built.  Is a signal generator useful?  Not to me!  Everything I do is digital, whether Arduino, Raspberry Pi, ARM or FPGAs.  I need a scope, I probably need a logic analyzer and that's about it.

Truth told, I don't need much of the bench equipment I have.  The Analog Discovery 2 can handle everything I do.  The Digital Discovery 2 is probably a better tool for pure digital but it doesn't have a scope feature.  Nevertheless, I have both and I use them more than any of my bench equipment.  Cheaper too!

I'm also certain that there are others around here who spend more time with audio or analog and less with digital.  Electronics covers a pretty wide field and there's room for everybody.  Their needs will differ, mine are fairly minimal.

Being retired leaves me more time to play with electronics so I added some tools over the last few years.  I have enough now to do just about anything I can imagine.

For giggles, I redid the recent FFT project using my AD2:

it may be that I will never use the FFT function, but having a tool and not knowing all its features leaves me a void inside; that's why I study her in all its details, I like to know her life.
I try to fix anything that comes my way, then I almost always don't fix anything, but those are details, I like to waste time on broken circuits. Of course I should understand if a function generator can help me: input of a desired signal in a portion of the circuit; I can't think they just use it to study signals with the oscilloscope, right?
As you rightly said, you now have more time and have broadened your horizons with new tools that you haven't used before for 50 years; this helps to stay young
 

[CharlotteSwiss]

w2aew (Alan Wolke) has a bunch of YouTube videos on simple circuits using transistors or op amps.  This is where I use my AWG the most - following along with what he is teaching.  I highly recommend his videos.  Dave has some "Fundamental Friday" videos that go into theory as well and the Op Amp video is excellent.  I tend to like the tutorial videos.

Here is a link to Alan's channel with the videos sorted by ascending date.  I tend to skip those related to ham radio but #65,66 and 67 jump right out.
https://www.youtube.com/user/w2aew/videos?view=0&sort=da&flow=grid

Dave's op amp introduction:

In the first minute Dave talks about why Op Amps were invented: analog computing, my favorite topic.  Integration, differentiation and arithmetic can all be performed with an op amp.  A multiplier is a little more complex but has been around for a long time.  In the old days it was based on a motorized variac.

Analog computing still exists.

https://en.wikipedia.org/wiki/Analog_computer

thanks for these videos, nice the one who uses the drills and displays the FFT spectrum, interesting that channel I will watch several of those videos.
On the other hand I have already met the op amps in some repairs, I have to watch this whole video of Dave, there is a lot to learn in there
 

[tautech]

it may be that I will never use the FFT function, but having a tool and not knowing all its features leaves me a void inside; that's why I study her in all its details, I like to know her life.
I try to fix anything that comes my way, then I almost always don't fix anything, but those are details, I like to waste time on broken circuits.

I swear, you have been looking over my shoulder ! 

Yes, curiosity has driven me too until I ended up with an equipment business which now I must have reasonable knowledge of the gear we sell and how it works. Result is, you, me and customers benefit. 

Today on the bench is a partly functional bench MCH K305D SMPS with LED display for V and A however the A measurement is somewhat incorrect. 
A brain teaser it will be.....and on NZ Fathers day ! 

SDG800 will fit most requirements until knowledge grows and more the more functionality that a 2ch AWG has is required. Sometimes, first cost (more) is last cost however it always depends on budget available.

[CharlotteSwiss]

FFT function, display setting: normal, max hold and average.
The average ok setting averages the amplitudes of each frequency and redraws the FFT graph constantly.
I didn't understand, however, what they put to the Times setting (4 to 1024); ok if I set 10 times, it starts to count 10 record acquisitions, but once finished .. I saw that the FFT graph is updated anyway; so it's not clear what the difference is between setting for example 4 times and 100 times ... seeing is believing
 

[tautech]

FFT function, display setting: normal, max hold and average.

They each have their value.

Some say they like normal to to see all the noise floor and average will make it cleaner without hiding information like max hold can do.
IDK but I prefer max hold.

[CharlotteSwiss]

thanks tautech
normal is realtime FFT
max hold is ok for see only the max peak
average it should average, but it is unclear what affects the value in the Times field
but that's okay 

[CharlotteSwiss]

the manual does not specify what the "difference in frequency" value that I indicated with a green arrow represents when we are viewing an FFT graph
 
any idea what these 23.84Hz represent? (the signal used is 1Khz)
thanks
 

[rstofer]

the manual does not specify what the "difference in frequency" value that I indicated with a green arrow represents when we are viewing an FFT graph
 
any idea what these 23.84Hz represent? (the signal used is 1Khz)
thanks
 

It is the width of the FFT bins.  During the calculations, frequency components fit into bins of some width that is determined by the width of the spectrum being evaluated and the number of samples.

http://support.ircam.fr/docs/AudioSculpt/3.0/co/FFT%20Size.html

[CharlotteSwiss]

It is the width of the FFT bins.  During the calculations, frequency components fit into bins of some width that is determined by the width of the spectrum being evaluated and the number of samples.
http://support.ircam.fr/docs/AudioSculpt/3.0/co/FFT%20Size.html

thanks rstofer, now it's clear.
There is no information abound with the manual 

For example I have been studying the math-d / dt function all afternoon, it's a big headache.
I understand that maybe I'm a beginner and certain topics are difficult to understand, but if they put some more information ...
I take a walk with my wolf dog, then when I come back I put an image on the d / dt graph of the square wave, honestly I didn't understand how it can help ...

 

[CharlotteSwiss]

I lightened my head by taking a walk with my quadruped 

function math- d / dt (differentiate) calculates the discrete time derivative of the selected source.
The siglent manual tells me this:

di= y(i+Δ t) - y(i- Δ t) / 2 Δ t

Where:
d = differential waveform
 y = channel 1, 2, 3, or 4 data points
 i = data point index
 Δ t = point- to- point time difference
The dx option under d/dt math function operation menu shows the point- to- point time
difference, and it ranges from 0.02div to 0.40div. “div” indicates the number of the pixel points that each division has. The oscilloscope has 50 pixel points per division. Take 0.2div as an example: 0.2*50=10. It means to calculate the ten point’s discrete time derivative of the selected source, and the Δ t is the ten point’s point- to- point time difference.
You can use differentiate to measure the instantaneous slope of a waveform. For example, the slew rate of an operational amplifier may be measured using the differentiate function

---
I honestly didn't understand much!
I understand that we have 14 horizontal divs, and each div has 50 pixels.
But I don't understand by looking at the d / dt signal what I can understand about that signal.
In the image there is the 1Khz compensation square wave signal, and in white the relative d / dt graph: I don't understand how it can suggest, for example, the rise time of the signal edge?

thanks 

[rstofer]

Page 115 if the User Manual describes the derivative function as 'change in voltage (or amperage) / per unit change of time".  It gets to the deginition of the derivative from Calculus I

https://siglentna.com/USA_website_2014/Documents/UserManual/SDS1000X&Xplus_UserManual_UM0101X-E02A.pdf

What it really does is give a better explanation for 'rise time' because the faster the change in voltage, the sharper the rise time and the more harmonics are required to achieve the rise time.

I put a square wave from my SDG2082X into my DS1054Z and I get a diff(V/t) of a little more than 1MV/second.  That's right!  The voltage on the edges is changing at 1 million volts per second.  Does that make sense?  Well, it is changing 4Vp=p (just to pick a number) and if it did that in 4 microseconds, the signal would be changing 4V/0.000004sec = 1,000,000 or 1MV/sec.  That isn't an especially fast rise time 4 us is nothing compared to a few picoseconds.  When we get to those time scales, the derivative gets quite high.

Why do we care?  Well it goes to the transitions - some devices want a minimum value of dV/dt in order to clock properly.  Slow op amps can't keep up with fast transitions. Or maybe we want to play with the capacitor equation i = C dv/dt.  A 1 ufd capacitor hit with a 1V/microsecond edge will pass an instantaneous 1A of current.

https://www.allaboutcircuits.com/textbook/direct-current/chpt-13/capacitors-and-calculus/

[rstofer]

Here is a datasheet for a common, but very old, op amp.  On page 5 notice the maximum "slew rate" is 0.5V/us or 500,000 V/s at unity gain   If the dV/dt value of the input is higher than 0.5V/us, the output won't track the input at unity gain.  It's the output that sets the slew rate so at gains above unity, the input slew rate is probably even lower.  This is not a very fast op amp but they were used by the millions for analog computing where the slew rate is 10V/second or perhaps 100V/second on the 10x inputs to the integrators.

https://www.ti.com/lit/ds/symlink/lm741.pdf

[CharlotteSwiss]

thanks rstofer, we had written almost at the same time. 
Now it's bedtime here in the Alps, tomorrow with a clear mind I read your last two speeches very well, let's see if this topic comes into my head.
Note: I found the math chapter quite complicated, it is certainly not an easy speech to understand; then I still have the integral and square ... then I hope that the manual continues with easier notions.
Good evening rstofer, in the USA it's not time to sleep yet ...
See you soon
 

[rstofer]

At my age (74) mid afternoon naps are becoming more common.  Mid morning naps are popular as well.  Plus another nap while watching TV before bed time.

[rstofer]

Skipping ahead to the integral, the scope does the obvious calculus things.

The first image shows the integral of a constant and then what happens when the constant changes - a square wave.  The integral (c dt) is c*t where t is the time over which the integration occurs.  As time goes by, the product c*t increases linearly - this results in a ramp.  In the product, the only thing that is changing is linear time, the constant is, well, constant.  When the constant changes, the ramp heads in the other direction.  This is integration at its easiest and is the basis for analog computing.

Pour a constant 5 gallons per minute into a 50 gallon barrel and plot the height of the water over time up to 10 minutes when it overflows.

The second image shows the integral of the sin(x) function (waveform) and the integral(sin(x)) is -cos(x) plus a constant which I will ignore.  Note the middle of the screen where the yellow sin(x) crosses 0V going positive and the blue is at its minimum value (not 0 but some negative value).  In a perfect world where the sin(x) varied from 0 to +1 to 0 to -1 and back to 0, the cos(x) would vary from +1 to 0 to -1 to 0 and back to +1 and -cos(x) would vary from -1 to 0 to +1 to 0 and back to -1.  I don't know why my Rigol isn't displaying the magnitude of -cos(x) properly but the idea is right.  It shows a cosine but the upper and lower values are wrong.  I'll probably have to read the manual.

See the screen image from Desmos.com  The red trace is sin(x) and the green trace is -cos(x).

Here is a table of simple integrals from Calculus II:

https://www.mathsisfun.com/calculus/integration-rules.html

In any event, integration may be important.  The voltage on a capacitor is 1/C * integral(i dt).  This makes sense because a larger capacitor takes  more current (or more time) to charge to the applied voltage.  Double the size of the capacitor and it takes twice as long to charge to some voltage given an identical current.  Again, this makes sense.

You can think of an integrator (or capacitor) as a bucket that accumulates something - perhaps charge.  Or the pressure in an air compressor tank.  When empty it starts at 0 psi and as the pump runs, more air is accumulated in a fixed volume so the pressure increases.  Or the barrel of water described above.

[CharlotteSwiss]

At my age (74) mid afternoon naps are becoming more common.  Mid morning naps are popular as well.  Plus another nap while watching TV before bed time.

think there are a lot of young people who sleep all day (the workplace is full ...)
Come on, you're still a differently young man; after all, it is the passions that keep us young, inside and out!
 

[CharlotteSwiss]

Page 115 if the User Manual describes the derivative function as 'change in voltage (or amperage) / per unit change of time".  It gets to the deginition of the derivative from Calculus I

https://siglentna.com/USA_website_2014/Documents/UserManual/SDS1000X&Xplus_UserManual_UM0101X-E02A.pdf

What it really does is give a better explanation for 'rise time' because the faster the change in voltage, the sharper the rise time and the more harmonics are required to achieve the rise time.

I put a square wave from my SDG2082X into my DS1054Z and I get a diff(V/t) of a little more than 1MV/second.  That's right!  The voltage on the edges is changing at 1 million volts per second.  Does that make sense?  Well, it is changing 4Vp=p (just to pick a number) and if it did that in 4 microseconds, the signal would be changing 4V/0.000004sec = 1,000,000 or 1MV/sec.  That isn't an especially fast rise time 4 us is nothing compared to a few picoseconds.  When we get to those time scales, the derivative gets quite high.

Why do we care?  Well it goes to the transitions - some devices want a minimum value of dV/dt in order to clock properly.  Slow op amps can't keep up with fast transitions. Or maybe we want to play with the capacitor equation i = C dv/dt.  A 1 ufd capacitor hit with a 1V/microsecond edge will pass an instantaneous 1A of current.

https://www.allaboutcircuits.com/textbook/direct-current/chpt-13/capacitors-and-calculus/

thanks rstofer, in the meantime I analyze d / dt (as soon as I archive this I read well your intervention 674 for the integrated)
I'm starting to understand something, and I also learned what slew rate is in op.amp datasheets
If I look at your test with the Rigol, I see that if you enable the diff function, the display shows you the value that is 1MV / s, and everything makes sense.
Now look at my attached image: usual compensation signal, as you can see the square wave values are 3.12v and a rise time of 984ns.
As you taught me, the d / dt should be: 3.12v / 0.000000984s = 3170731V / s
As you can see, the only data he shows me related to d / dt are the vertical divs (100kv / s) and the position on the display.
What good can this view be for me, if it doesn't even tell me the d / dt value? or maybe I'm missing something?
In your Rigol it makes sense, you enable the diff and it indicates the V / s relative to the ramp rise time of the signal ... but in my Siglent what do I do with this d / dt graph?
I don't think the usefulness of the d / dt function is to observe its white graph, I don't see what it can tell me exactly ...
 
 

side note: siglent engineers had no imagination: they decided to color the writings of the math functions in pink .. such as the writings relating to the values of ch2 

after 4 edits I give up: I saw that if I change the sec / div of the signal, it changes the Vpk-pk of the diff track, so it does not represent the dv / dt value ...
point to head ...

[Mechatrommer]

At my age (74) mid afternoon naps are becoming more common.  Mid morning naps are popular as well.  Plus another nap while watching TV before bed time.

dont you regularly go to Wallmart/McDonalds anymore?

[rstofer]

At my age (74) mid afternoon naps are becoming more common.  Mid morning naps are popular as well.  Plus another nap while watching TV before bed time.

dont you regularly go to Wallmart/McDonalds anymore?

If it fits in between my naps...

I have been retired, and comfortably, for 17 years.  I get to play, and nap, as much as I want and never have to commute.
Social distancing hasn't been a problem, I've been doing it since I retired.