Putting an oscilloscope on the simple buck converter circuit. Measuring voltage and current in the circuit. Trying different switching frequencies and different inductors.
https://playground.arduino.cc/Main/TimerPWMCheatsheet

By Julian

Youtuber, shed dweller, solar charge controller aficionado

16 thoughts on “Let’s scope a buck converter”
  1. Avataaar/Circle Created with python_avatars Sauvik Roy says:

    Nice explanation! If you vary the load, how would it affect the smoothing?
    If you added a parallel capacitor to the inductor, instead of in series, how will it affect the output waveform?

  2. Avataaar/Circle Created with python_avatars Arko says:

    🇳🇱🤔🤔🤔🤔🤔🤔🤔🤪🤪🤪🤪🤪🤪🤪🤪🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏👍👍👍👍👍👍👍👍👍👍

  3. Avataaar/Circle Created with python_avatars Pieter van Woudenberg says:

    No captioning!!! Not for deaf people!

  4. Avataaar/Circle Created with python_avatars Steve Bliss says:

    31KHz did the trick, by not letting it get saturated.

  5. Avataaar/Circle Created with python_avatars Steve Bliss says:

    Yep, massively SATURATED. A bit above 3½ trace bars is where the inductor saturates (i.e. stops being an inductor, and becomes a wire).
    If you reduce the number of turns a LOT, it may fix it. 🙂

  6. Avataaar/Circle Created with python_avatars Mukesh Tak says:

    sir I want to make high frequency switch of upto 1 Mhz and adjustable duty cycle. please suggest any irf540n mosfet driver for high speed switching of upto 20 V and the current flowing in the circuit is less than 1 A

  7. Avataaar/Circle Created with python_avatars phmountaindog says:

    A buck converter steps down voltage by a variable FREQUENCY, you are using PWM which isn't the same. With PWM you have the same frequency but variable duty cycle.

  8. Avataaar/Circle Created with python_avatars Brandon Corby says:

    Like the 3rd video and you still have yet to put a output cap on it.

  9. Avataaar/Circle Created with python_avatars Tem Tem says:

    I want this video in Arabic please😢 I need it much

  10. Avataaar/Circle Created with python_avatars Gu Si says:

    @Julian Ilett can you add current limit to a buck? Mixing two pwm together one slow the other fast kind of like pulse frequency modulation (pfm) to limit current?

  11. Avataaar/Circle Created with python_avatars juliusvalentinas says:

    I can suggest you to scope a ton of buck converters you have to see what khz do they run on with power LED 1-3W etc. connected, this is very important for using it as LED driver and avoiding flicker to camera CCD. If the khz range is high enough when gone dim it should not flicker. I think many would appreciate this as not everyone has a scope and believing Chinese specification is stupid at best.

  12. Avataaar/Circle Created with python_avatars chuck duck says:

    yo…Love your vids….and you have good english…also I have learned alot from you thanks….So Question. is their a relay or
    circuit or a way to …switch from lets say a 12 volt battery pack when its gets drawn down to 9 volts ….and automatically
    switch to another pack..of 12 volts…so you dont have to plug and unplug units…..thanks Charlie…

  13. Avataaar/Circle Created with python_avatars Alan Yelvington says:

    Using a pencil as a pointer for electrical circuits has been the death of some. It would be best if you used something insulated.

  14. Avataaar/Circle Created with python_avatars yeme says:

    Julilan Id love to know the values of the inductors youre using here, stick them in your component tester?

  15. Avataaar/Circle Created with python_avatars nTOOBEa says:

    Sweet… But you should have scoped it with cap too.

  16. Avataaar/Circle Created with python_avatars Ronell Oropesa says:

    One of the inductor's characteristics is resisting the change of current passing through it. So in a buck converter when the PWM is HIGH the initial current passing through the inductor is zero and as time passes it begins to increase. The gradual increase of current gradually increase the voltage across the load (Ohm's Law V=IR). When the PWM is LOW the initial current in the inductor is the max current that flows through it during the PWM's HIGH state.

    Cutting off the current from the source, the inductor's current goes down but because it resists the change of current the rate of decrease is slow. That is why comparing the SIGNAL from the FET to the SIGNAL across the load (inductors output), we will see that the FET's shift from low to high and vice versa is almost discontinuous while on the LOAD's side its gradually increasing and decreasing. We might also see that the signal from the load is out of phase from the PWM's signal.

    Hope my analysis is right. =)

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.