Measuring power supply ripple with Siglent 1202X-E

[tautech]

None at all. What you have now is fully capable for these tasks and better than most and offering 500uV/div sensitivity.

I don't think he's considering upgrading.  I think he means his Sgilent is the "expensive" scope.

$379 expensive ? 

It's all relative.  Compared to a Hantek or a Fnirsi it is or even to lower end Siglents and Rigols. It's 10 times the price of a DSO154 Pro!!

Offering the same sensitivity and BW....nope !

[BillyO]

Offering the same sensitivity and BW....nope !

Of course not.  Hey, you don't have to sell me on Siglent.  You basically already did.  To the tune of about $4K spent in the last 16 months.

Just sayin' that there a lot of folks on the EEVBLOG forum to whom $379US is a lot of money.

[tautech]

Just sayin' that there a lot of folks on the EEVBLOG forum to whom $379US is a lot of money.

And some will learn hard lessons buying the cheapest, untested/unproven pretty looking gear.
Also just saying.

[BillyO]

And some will learn hard lessons buying the cheapest, untested/unproven pretty looking gear.
Also just saying.

I'm in complete agreement on this.

However, in the extreme if all you have is $50 to buy a scope then a $50 scope is better than no scope.  Think of it as a "gateway" instrument.  The neophyte will learn some things and be able to visualize signals which will aid their progress in their electronics hobby to the extent they will eventually find themselves in need of a better instrument and understand the value in the purchase price.

[tautech]

And some will learn hard lessons buying the cheapest, untested/unproven pretty looking gear.
Also just saying.

I'm in complete agreement on this.

However, in the extreme if all you have is $50 to buy a scope then a $50 scope is better than no scope.  Think of it as a "gateway" instrument.  The neophyte will learn some things and be able to visualize signals which will aid their progress in their electronics hobby to the extent they will eventually find themselves in need of a better instrument and understand the value in the purchase price.

Instead many also learn a scope is just the start, HV, differential and current probes are also must haves and investments in that can be used on any scope although it is very useful to have input attenuations settings that can match any probe instead of in your head calculations like we had to do with CRO's. 
Back in them days I played a lot with magnetics and then you could find the great P6021 current probe for under $100 but sadly far less so these days.
CRO's, I had a few and several Tek DSO's also, none of which can compare with modern DSO's of the last 5 or so years.

[BillyO]

And some will learn hard lessons buying the cheapest, untested/unproven pretty looking gear.
Also just saying.

I'm in complete agreement on this.

However, in the extreme if all you have is $50 to buy a scope then a $50 scope is better than no scope.  Think of it as a "gateway" instrument.  The neophyte will learn some things and be able to visualize signals which will aid their progress in their electronics hobby to the extent they will eventually find themselves in need of a better instrument and understand the value in the purchase price.

Instead many also learn a scope is just the start, HV, differential and current probes are also must haves and investments in that can be used on any scope although it is very useful to have input attenuations settings that can match any probe instead of in your head calculations like we had to do with CRO's. 
Back in them days I played a lot with magnetics and then you could find the great P6021 current probe for under $100 but sadly far less so these days.
CRO's, I had a few and several Tek DSO's also, none of which can compare with modern DSO's of the last 5 or so years.

I'm looking to expand (it's a disease, I tell ya what!) but I think a real differential probe will never be a part of my kit.  But maybe a half decent current probe.

I just bought a new truck.  A Toyota Tacoma with all the trimmings.  I usually take good care of my vehicles and it will probably last me 15-20 years.  It cost $56K.  It's kind of funny but that kind of money is a pittance to what you can spend buying a TOTL oscilloscope or other piece of best in world test equipment.  But those are on a different level.  For the most part they can't even be applied to the stuff most of us work with.  You literally have to design the DUT to be tested by them.

Anyway.  I still have 2 CRO's.  Kind of a part of my hobby is to use vintage test equipment to work on vintage electronics.  I even have a separate "vintage" bench.
One scope is a venerable Tek 465, the other I just picked up recently for $40, is a Heathkit IO4205.



It's a 2 channel, 5MHz monster from the 80's and is a total nostalgia boost for me.  My first scope ever was the Heathkit IO4105 I built in 1980.  The single channel version.  Speaking of boot times .. 7 seconds to visible traces.  Anyway, it may be ancient and it may be a CRO and it may be as big as a microwave oven, but it's a darn sight better instrument than any cheap little $40 2" screen, single cahnnel 200KHz scope like the DSO138.

[tautech]

I'm looking to expand (it's a disease, I tell ya what!) but I think a real differential probe will never be a part of my kit.  But maybe a half decent current probe.

Mostly a differential probe doesn't need to be too flash but provide good voltage isolation.
Something like the old DP25 used with care can serve you well.
https://www.pintek.com.tw/productDetail/land-ctop-2/index/pscsn/17072/psn/19265

I just bought a new truck.  A Toyota Tacoma with all the trimmings.  I usually take good care of my vehicles and it will probably last me 15-20 years.  It cost $56K.

  Never ever spent that much on wheels. 

It's kind of funny but that kind of money is a pittance to what you can spend buying a TOTL oscilloscope or other piece of best in world test equipment.  But those are on a different level.  For the most part they can't even be applied to the stuff most of us work with.  You literally have to design the DUT to be tested by them.

Yet as you know for what your new wheels cost you can now set up a very respectable lab with what the leading Asian brands offer.

Anyway.  I still have 2 CRO's.  Kind of a part of my hobby is to use vintage test equipment to work on vintage electronics.  I even have a separate "vintage" bench.
One scope is a venerable Tek 465, the other I just picked up recently for $40, is a Heathkit IO4205.

Basically that's how I got/fell into this game after fixing my first gifted CRO when in my 40's as life had been too busy to continue with electronics since a childhood start.
After fixing many more and a few DSO's I knew they were the future in the reliability stakes.

It's a 2 channel, 5MHz monster from the 80's and is a total nostalgia boost for me.

Not sorry to say I gave the CRO bit up completely some 10yrs back when I got a 300 MHz DSO and regrets are none. 
However I do count myself lucky to have been along for the ride with Siglent and 9yrs is too long since I last visited them. However not sure I want nasal passages explored just to get clearance to get on a flight to Shenzhen. 

[BillyO]

Something like the old DP25 used with care can serve you well.

It's a bit marginal on the BW, but beyond that they seem to have a lot of interesting products.  However, I don't think they are interested in retail sales.
I guess if I can find another 9999 interested parties we could get a container of them at a reasonable price (maybe a bit of an exaggeration, but maybe not).

But thanks Rob, I appreciate the discourse.

[tautech]

Something like the old DP25 used with care can serve you well.

It's a bit marginal on the BW, but beyond that they seem to have a lot of interesting products.

It will suit most needs.

However, I don't think they are interested in retail sales.

Yes Pintek have minimum buying limits which works fine for us.
They do have a few resellers and have been around for years however mainland Pintech have stolen their designs and customers.

[Performa01]

Even if some of this noise is common mode it's still noise being produced by the power supply and in many cases, like where the powered equipment if ground referenced or will be connected to ground referenced equipment, it becomes a factor.  It will even affect circuitry it is attached to through currents created by radiated energy.  I see no reason to ignore it by filtering it out. 

Thank you very much for all your posts, they have helped me a lot to understand how difficult it is to measure the ripple of a power supply.

And it leads me to the next reflection, does it make sense to buy an expensive oscilloscope if you are in a noisy environment?

The SDS1202X-E is low noise with true 500 µV/div sensitivity. It can't get much better than this, regardless of the price.

No matter how expensive a scope is, it won't help you with the environment. About the only way to get rid of environmental (= common mode) noise is to use differential probes. Even though the active probe support found on the more expensive midrange scopes might encourage the use of such probes, this is not much more than a matter of convenience.

[Fungus]

And it leads me to the next reflection, does it make sense to buy an expensive oscilloscope if you are in a noisy environment?

You can usually work on the background noise to reduce it. 

[Fungus]

$379 expensive ? 

Yep, and this is your blind spot...

[Fungus]

Offering the same sensitivity and BW....nope !

But not everybody needs that. 500uV and 200MHz will make no difference at all to the average Arduino hacker.

[Caliaxy]

Here is how I tested the ripple & noise of DC power with Scope:

- The DC power supply and the Scope are powered by an isolating transformer to ensure that they are not affected by AC mains. If I want to be more precise, I will separate the power supply for the oscilloscope from the AC mains, while the DUT is powered by an isolation transformer.
- Coax cable attached to the Siglent SDS1104X-E.
- At the output of the DC source, I connect 0.1uf+10uf (50V) ceramic capacitor in parallel, and use a 0.01uf capacitor to block the DC signal. I tried replacing the 10uf ceramic capacitor with a 10uf Tantalum capacitor but the results didn't make much of a difference.
- Ripple & noise about 3.36 mVp-p.
Compared to using probe with GND wire ripple & noise about 8.96 mVp-p

Another example compares the ripple & noise of 65W GaN charging when using the oscilloscope probe far from the source with using a coax cable near the output of the source, the results will be different.

No 50 ohm termination?

[tautech]

$379 expensive ? 

Yep, and this is your blind spot...

You think ?
My eyes are wide open and can well see the poo that's offered to the marketplace.....bit of a shame buyers of that poo don't have their eyes open too.

[MarioBros69]

What I wanted to say is, what's the point of buying a 500 uV/div oscilloscope if I have such a noisy environment?
Anyway, after reading and learning from your answers, I understand that the first thing to do (if that is possible) is to avoid the source of noise.

My intention is to buy a 1104X-E but they sent me a 1202X-E by mistake, I have returned it and in the next few weeks I have to decide which one to buy, so read this forum a lot

By the way, the more I read the forum the more money I want to spend

At my age (55 years old) and my little knowledge of electronics belongs to the era of analog oscilloscopes, I recently decided to return to electronics as a hobby and I am buying some equipment

This week someone close to where I live sells me a KIKUSUI 5060 analogue in good condition for just under 100 euros and since my knowledge of electronics is limited maybe it is enough for a simple hobby

I have many doubts

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[nctnico]

Skip the old crap unless you want to have a hobby keeping your equipment running.

[markus_jlrb]

If you could not effort or use diff probes, I would like to recommend a
battery drive scope like the OWON HDS2xxx devices.
 40MHz BW -> HDS2042(S)
 70MHz BW -> HDS2072(S)
100MHz BW -> HDS2102(S)
200MHz BW -> HDS2202(S)

The S-models include a build in 20MHz sig. generator (sinus) 5MHz (rectangle) and arbitrary sig. formats.

For a beginner it is more secure as you avoid the GND/shortage problematic while taking your measurements.
Nevertheless it's important to understand how to connect DSO/Scope and DUT in a secure way to avoid a damage
of your device and/or your DUT.

Markus

[MarioBros69]

If you could not effort or use diff probes, I would like to recommend a
battery drive scope like the OWON HDS2xxx devices.
 40MHz BW -> HDS2042(S)
 70MHz BW -> HDS2072(S)
100MHz BW -> HDS2102(S)
200MHz BW -> HDS2202(S)

The S-models include a build in 20MHz sig. generator (sinus) 5MHz (rectangle) and arbitrary sig. formats.

For a beginner it is more secure as you avoid the GND/shortage problematic while taking your measurements.
Nevertheless it's important to understand how to connect DSO/Scope and DUT in a secure way to avoid a damage
of your device and/or your DUT.

Markus

Thank you very much for the advice, after reading many in this forum my current idea is to buy a 1104X-E but I will also take your advice into account

Do you mean that since the oscilloscope is portable and not connected to 220v, I will no longer have noise when taking the measurement?

[Performa01]

Do you mean that since the oscilloscope is portable and not connected to 220v, I will no longer have noise when taking the measurement?

A battery operated scope can measure differential signals (i.e. wihout ground reference) with some griefs when in a pinch, but that does not magically turn the single ended (asymmetric) scope inputs into well blanced differential ones. Consequently, the common mode rejection will be quite bad, especially at higher frequencies.

Sensitive measurements require proper probing techniques, simple as that. Yet a modern DSO can help you with this, even when the signal of interest is drowned in environmental noise. For instance, just to measure the ripple of a linear power supply, you could use AC line triggering and average acquisition mode to get the signal clearly visible and make precise measurements.

[Martin72]

Here is a short paper concerning ripple measurements, mainly on switching power supplies.

[MarioBros69]

Here is a short paper concerning ripple measurements, mainly on switching power supplies.

Thank you for the document..., it is very interesting

[tautech]

Do you mean that since the oscilloscope is portable and not connected to 220v, I will no longer have noise when taking the measurement?

Let's look a little harder at this particular measurement.

It's a linear PSU with isolated channels however there is provision to tie any output to mains Gnd:
(middle terminal)



When doing so the antenna effect of a probe reference lead is much reduced as this places the reference lead at the same mains ground potential and noise should be substantially reduced.

Screenshots please when you get your SDS1104X-E. 

[MarioBros69]

Do you mean that since the oscilloscope is portable and not connected to 220v, I will no longer have noise when taking the measurement?

Let's look a little harder at this particular measurement.

It's a linear PSU with isolated channels however there is provision to tie any output to mains Gnd:
(middle terminal)

When doing so the antenna effect of a probe reference lead is much reduced as this places the reference lead at the same mains ground potential and noise should be substantially reduced.

Screenshots please when you get your SDS1104X-E. 

Do you mean that I should connect the negative of the oscilloscope probe to the ground terminal and the positive of the probe to the positive terminal?

I have doubts about the purchase, now someone tells me that instead of the 1104X-E I should spend a little more and buy the Rigol MSO5074

The more I read the more doubts
Thanks

[tautech]

Do you mean that since the oscilloscope is portable and not connected to 220v, I will no longer have noise when taking the measurement?

Let's look a little harder at this particular measurement.

It's a linear PSU with isolated channels however there is provision to tie any output to mains Gnd:
(middle terminal)

When doing so the antenna effect of a probe reference lead is much reduced as this places the reference lead at the same mains ground potential and noise should be substantially reduced.

Screenshots please when you get your SDS1104X-E. 

Do you mean that I should connect the negative of the oscilloscope probe to the ground terminal and the positive of the probe to the positive terminal?

That's what happens if you ground (link center terminal) the negative side of the PSU output.

Passive probes don't have negatives and positives, the reference lead is always at mains ground potential in all scopes except isolated channel versions.

I have doubts about the purchase, now someone tells me that instead of the 1104X-E I should spend a little more and buy the Rigol MSO5074

If you want to see even more noise at low signal levels the 5074 has substantially more system noise that excludes it from precise low level measurements.

The more I read the more doubts

Good, members knowledge can help you understand and grow.