Author Topic: How to measure voltage ripple with an osciloscope  (Read 3816 times)

0 Members and 1 Guest are viewing this topic.

Offline JaneTopic starter

  • Frequent Contributor
  • **
  • Posts: 381
How to measure voltage ripple with an osciloscope
« on: May 21, 2015, 06:04:25 pm »
Is it possible to use Hantek 200Mhz scope and  measure 50mV (5%) ripple of a voltage from the  reference value?
(That ripple can last for a very short time)
 

Online wraper

  • Supporter
  • ****
  • Posts: 16797
  • Country: lv
Re: How to measure voltage ripple with an osciloscope
« Reply #1 on: May 21, 2015, 06:18:26 pm »
Set input to AC coupling, profit.
 

Offline Asmyldof

  • Regular Contributor
  • *
  • Posts: 148
  • Country: nl
  • Freelancer - Persnicketist - Do'er of stuff
    • Asmyldof's Home. It's old, not quite impressive, but it's there.
Re: How to measure voltage ripple with an osciloscope
« Reply #2 on: May 21, 2015, 06:21:00 pm »
I think you are looking for the "AC coupling" setting.

I'm too lazy to look up the device, but Hantek and 200MHz make me believe it should have "AC/DC" or "AC coupling" written on the case next to a button.

Basically you are telling the scope to either measure everything (DC coupling) by applying "a straight wire" from input to measurement system (whether analogue deflection or ADC), or measure only the AC content (AC coupling) by effectively putting a galvanic separation between input and measurement system. Much like the decoupling caps on analogue amplifiers and such, only with a more rigidly controlled impedance matching, I'd expect.

(paraphrasing of course)
If it's a puzzle, I want to solve it.
If it's a problem, I need to solve it.
If it's an equation... mjeh, I've got Matlab
...
...
(not really though, Matlab annoys me).
 

Offline JaneTopic starter

  • Frequent Contributor
  • **
  • Posts: 381
Re: How to measure voltage ripple with an osciloscope
« Reply #3 on: May 22, 2015, 08:04:34 pm »
Thanks for the replies.
Yes, in my Hantek too, there are possibilities:
AC coupling
DC coupling
Ground

So, if need to measure a ripple of DC , I just choose  AC coupling?
And where is useful to chose DC coupling and Ground option?
 

Offline Asmyldof

  • Regular Contributor
  • *
  • Posts: 148
  • Country: nl
  • Freelancer - Persnicketist - Do'er of stuff
    • Asmyldof's Home. It's old, not quite impressive, but it's there.
Re: How to measure voltage ripple with an osciloscope
« Reply #4 on: May 22, 2015, 08:58:33 pm »
As I pointed out, the DC option shows you all of the signal. It is very useful to compare an AC ripple to the DC, or if you are actually interested in DC or very low frequency waves.

The AC coupling doesn't work well for things below a couple of Herz.

Ground is to show you the baseline, if the device connects the signal to ground internally it will be the most noise free ground there is, so you can see and adjust the origin of your signal.
(And possibly debug input stage problems if it still shows distinguishable signals)
If it's a puzzle, I want to solve it.
If it's a problem, I need to solve it.
If it's an equation... mjeh, I've got Matlab
...
...
(not really though, Matlab annoys me).
 

Offline John_ITIC

  • Frequent Contributor
  • **
  • Posts: 507
  • Country: us
  • ITIC Protocol Analyzers
    • International Test Instruments Corporation
Re: How to measure voltage ripple with an osciloscope
« Reply #5 on: May 22, 2015, 09:08:03 pm »
Is it possible to use Hantek 200Mhz scope and  measure 50mV (5%) ripple of a voltage from the  reference value?
(That ripple can last for a very short time)

What you'll do is to set the input to AC mode such that only the ripple will be displayed, not your DC base voltage. Then set the trigger to trigger on negative going pulses. Finally, adjust the trigger level down from 0V. As the ripple causes the voltage to deviate from the base-line, the AC voltage will dip causing the scope to trigger. At some point it will be harder and harder to trigger. At that point, you have your maximum negative ripple. Do the same for positive going ripple, if you are interested in it.

With a 200 MHz bandwidth scope, you may not see the ripple caused by fast switching circuitry. It may show a lower ripple than what is actually there.

/John.
Pocket-Sized USB 2.0 LS/FS/HS Protocol Analyzer Model 1480A with OTG decoding.
Pocket-sized PCI Express 1.1 Protocol Analyzer Model 2500A. 2.5 Gbps with x1, x2 and x4 lane widths.
https://www.internationaltestinstruments.com
 

Offline tautech

  • Super Contributor
  • ***
  • Posts: 28141
  • Country: nz
  • Taupaki Technologies Ltd. Siglent Distributor NZ.
    • Taupaki Technologies Ltd.
Re: How to measure voltage ripple with an osciloscope
« Reply #6 on: May 22, 2015, 09:30:42 pm »
@Jane
In your OP you mention ripple for a short duration.
After setting your scope to AC coupling and channel attenuation (v/div) for expected ripple levels, in order to see or capture fast events you'll need to use Single shot. The Trigger level setting then determines when the capture is made. The Trigger suite available makes a DSO a powerful tool and more so the operators ability to use that suite.  ;)
Avid Rabid Hobbyist
Siglent Youtube channel: https://www.youtube.com/@SiglentVideo/videos
 

Offline Shock

  • Super Contributor
  • ***
  • Posts: 4200
  • Country: au
Re: How to measure voltage ripple with an osciloscope
« Reply #7 on: May 23, 2015, 12:19:53 am »
Here is a video someone made on youtube

Soldering/Rework: Pace ADS200, Pace MBT350
Multimeters: Fluke 189, 87V, 117, 112   >>> WANTED STUFF <<<
Oszilloskopen: Lecroy 9314, Phillips PM3065, Tektronix 2215a, 314
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf