How to Measure Ripple Voltage on a Switch-Mode Supply - Workbench Wednesdays

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Published 2022-03-02
Measuring a switch-mode power supply (SMPS) with a DMM might show a stable voltage. But the same DC rail on an oscilloscope can show a completely different story! In this video, learn how to correctly set up an oscilloscope to characterize the noise an SMPS creates in a circuit. bit.ly/3tkVbFd

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#0:00 Welcome to Workbench Wednesdays
#0:52 What is Ripple?
#1:27 Equipment Needed
#2:20 Oscilloscope Setup#6:31 1:1 Probes
#9:43 Measurement Observations
#11:13 Give your Feedback

#SMPSripple #ripplevoltage #ripplenoise #oscilloscope #multimeter
All Comments (21)
  • @Electronzap
    Good video! I didn't know resistors came in TO-220 packages, but not surprised. Makes a lot of sense!
  • @sumitmamoria
    Nice video. Would be very interested in measuring loop stability. 👍
  • @reasonablebeing5392
    Useful video!! Interested in seeing a project for a 30 Amp 5V power supply with adjustable + or - 2V to account for losses at the load.
  • @Tarbard
    Good video. The electronic load is more expensive that I would have thought.
  • @Chris-ut6eq
    Interested in all aspects of SMPS characterization. Also interested in hobbyist level scope review. And yes, making my own SMPS as a hobbyist :)
  • @jstro-hobbytech
    not that I'm don't droll over things on the site or your gear. I don't have gear envy. I've worked my way up to a decent siglent I got last week. having a mouse pointer right on the scope screen is better than touch haha
  • @snivesz32
    When measuring voltage ripple of a power supply, its customary to put in AC mode, at 20Mhz, and put the power supply under load, but is it normal to put a 0.1uF capacitor in parallel with the output terminals? Wouldn't that serve to suppress the very AC noise we are trying to measure? The Riden video instructs us to measure Vpp ripple in this fashion, why would that be?
  • @sueserich1587
    Hey m8 my cb radio base station 240v mains has a very noticeable hum even with the volume down, it is not a switch mode but linear, any suggestions? Cheers
  • @stanislavpopelka2721
    How has the power rail probe been connected? For Vout ripple measurement, the GND clip cable on the passive probe should be avoided due to the large ground loop. E.g., a spring adapter is more suitable for this kind of measurement.
  • @windward2818
    As I understand power rail probes, their operation requires the power supply rail to be below a certain impedance over frequency as to not form a divider with the probe. This is not usually a problem if the power rail probe is used as a final test for ripple after the power supply impedance has been fine tuned (no peaking). So, the testing approach may be follow a set procedure of equipment and tests performed depending on how the lab is equipped.
  • @Joeballs187
    Linus tech tips was just talking about a cameras battery could you watch the bored on that so we can see what's actually happening there
  • @change_your_oil_regularly4287
    Doesn't the required minimum load depend at least in part on the output voltage? 1k ohm @ 5v = 5mA 0.025w 1k ohm @ 240v = 240mA 57.6w I could easily be wrong I'm no electrical engineer just a hobbyist