Square waves, harmonics, and FFT

[@captainpugwash4100]

Just love the oscilloscope videos.

[@icenesiswayons9962]

I hope that I speak for others as well as myself, in that understanding the oscilloscope is a mystery to many in the beginning. Other than wading through many hours of tech classes, hoping to catch a simple glimpse of understanding its purpose and practical use. You are pushing down the barriers of frustration. My only complaint is your weren't there for me years ago, lol.:-) good video, keep up the great work.

[@learnelectronics]

Thank you very much.

[@YouAllKnowBob]

Fascinating. That's something I didn't know. Great video! 👍👍

[@learnelectronics]

Thanks!!

[@leachim66]

This is incredibly helpful. Your videos have helped me so much in my journey into electronics. Keep up the good work!

[@learnelectronics]

Thank you

[@samwalsh616]

As someone learning synthesisers and their oscillators & filters, it always confused me how other videos say square/pulse waves have certain frequencies, but then show the up&down square waveform and never explained it. This video did a much better job than all the videos I've seen, and made it click for me. So it's just displaying voltage/time, and you need a different display to see harmonic content. I know pretty much nothing about electronics but this channel looks like a great way to learn. Aologies for the stupid question - are synthesisers essentially like any other electrical circuit, but at audible frequencies? Thanks for the great video, I've subscribed.

[@fredericch54]

In order to further popularize, you could also approach additive synthesis, how to recreate a square wave by adding sinusoidal harmonic frequencies with amplitude according to the Fourier series development. This would also lead you to present the Gibbs effect. Continue this way because you present things well, with your experience!

[@andrewcalvo4762]

Excellent video. Thank you so much for publishing this. Looking forward to more of your work. For a little bit of context, I’m an undergraduate electrical engineer studying at the University of California at Santa Cruz. I’m in my fifth year right now taking high-speed digital design and this video was extremely helpful.

[@learnelectronics]

Thanks!

[@saysphilippe]

So cool! I have one of these wave generator, so when I get my Rigol it's party time :) Great work as always!

[@ed-jf3xh]

Good job, keep it up. A lot of people benefit from these trips back to basics.

[@learnelectronics]

Thanks

[@georgechambers3197]

Now that's some deep oscilloscope stuff. I didn't understand much but it was still interesting. Thanks for the video!

[@learnelectronics]

Thanks. It was just showing that a square wave is made up of an infinite series of sine waves at odd harmonics. So 1khz sq wave is made of sine waves at the fundamental, 3khz, 5. 7, 9, 11 etc all stacked on top of the original 1khz wave.

[@georgechambers3197]

Well, why didn't you just say so! 🤣

[@stevenbrown8782]

I had the same condition. My EF was below 10. Went from Pacemaker to Defibrillator to Heart Pump to Transplant to cancer to remission. I'm still here though. Seaton Hospital in Austin Texas was my transplant coordinator and performed the transplant. Great job, they did. I don't know your location but have you looked into a transplant coordinator? I reiterate that Seaton was great for me. Take care.

[@icenesiswayons9962]

@Steven Brown my wife just passed from CHF, she suffered, I believe more than she should have because of the quality of life after the dblbyps was absoluty nil for 2 years to say the least. Her levels of hypoxia went from nonexistent to every other night. Considering our initial hope, (She never saw the Dr after he performed her bypass), proved to be short lived, do to a constant shift in doctors unfamiliar with her case and supposedly providing her health care. Needless to say, as always with the typical excuses med professionals are famous for. Take care of your self and don't be complacent, ask ?'s. It may save your life.

[@bblod4896]

Sine, sine, everywhere a sine Blockin' out the scenery, breakin' my mind Do this, don't do that, can't you read the sine? Thanks for the lesson.

[@learnelectronics]

So I tucked my scope up under my hat...

[@bblod4896]

@@learnelectronics "and I went in to ask him why"

[@davidcoe9634]

great explanation

[@g00glian0]

That was intense. Must watch again...

[@PawOfRizzo]

I don't fully understand all this, but I work with IT equipment, and attentuation is a consideration, especially with wireless networks. So it is interesting to see the scope "visualize" the attentuation of the frequency. Even as a beginner I always take away little tidbits from each video. Thanks for your work!

[@learnelectronics]

Thank you

[@Venomator.]

Thank you Paul... 👍🏻 Another trick to experiment with on my ‘scope - assuming my Hantek is capable of FFT... 🤔 🤓 🐍

[@learnelectronics]

Desktop? Yes. USB? No

[@Venomator.]

learnelectronics - Desktop indeed, after your recommendation some months ago! thank you for responding Paul... 👍🏻 😉 🐍

[@robertcalkjr.8325]

Thanks Paul!

[@Helmut314]

I really need to get myself a proper scope...

[@robertcalkjr.8325]

Yes, you do. I have no doubt that I would have learned electronics faster had I bought a scope in the beginning.

[@jasoneyes01]

Thanks for the lesson!

[@MCsCreations]

This is really, REALLY, interesting!!! Let me ask you something... And if you know nothing about rc and quadcopters, don't worry, you can ask me. So... There's this guy that has a channel and he does a lot of esc testing, looking for its noise profile. Long story short, escs (electronics speed controllers) drivers the brushless motors... Which are really noise, for a lot of reasons. (They have really strong magnets, they don't only burn current for spinning, but also generate electricity when doing that and so on.) And the noise is terrible for quadcopters, it gets into the gyro and can cause a lot of undesirable movements in the PID loop, it can ruin your video feed of the FPV if the noise gets to the VTX and so on... Anyway, there's lots of criticism about his results... People questions about the way he connects the oscilloscope and so on. But nobody shows any evidence that his tests are flawed either. So, my question is how would you hook it up? And what would you look for?

[@learnelectronics]

I'm sorry, that's really not my field.

[@MCsCreations]

@@learnelectronics I see... Thanks anyway. 😊

[@michaelpadovani9566]

It's amazing to think how important FFT is. Most people don't know that's essentially how the internet chauffeurs signals across the world. Think modems and bandwidth.

[@Burbah]

This is a great explanation but I still feel that there's a deeper base of understanding to this which I haven't grasped yet... Why are a bunch of sine waves in odd harmonics are represented as a square? What is it in the sudden movement of the square wave that creates the different harmonic sine waves in the first place? What am I missing here? Is it the speaker that moves from one point to another so suddenly that it creates a by product of "color" and from the movement itself come the harmonies which is the distortion we hear? Is it in the circuit that when overdriven lets out these harmonies? Or is it something else? Because there is a wave that's oscillating back and forth instantaneously and I don't seem to understand how filtering it's high frequencies makes it a sine wave again... These dots do not connect for me.

[@rolandberendonck3900]

Unfortunately this is above my head... So sorry, but that's why I am out.

[@oldiron1223]

My "Fundamentals" courses were over 30 years back so....how is FFT different than a spectrum analyzer display? Back when the dinosaurs roamed it was explained to me as o-scope vertical = voltage, horizontal=time. Spectrum analyzer vertical=power (Db or Dbm) horizontal=frequency. FFT shows power over frequency or a hybrid voltage over frequency ?

[@learnelectronics]

FFT on a scope is just a very basic spectrum analyzer done in software. Frequency in the horizontal plane, amplitude in vertical.

[@oldiron1223]

@@@learnelectronics Thanks. The "latest" computerized scope I worked with would do basic data capture and not much else.

[@g00glian0]

What is the math behind the 1 KHz signal, the 1 Kohm resistor, and the .1 mF capacitor? How does one know that the resistor and cap values will resonate along with the 1 KHz signal(I'm not sure If I'm saying the right things)? Anyway to give a brief example in the comment section here?

[@learnelectronics]

Low pass filter theory. Google low pass filter formula

[@rrowan327]

Hi Paul, Another great video. I got the same scope during last Christmas. The fan noise drove me (more nuts) so I followed other owners and swapped out the fan. It was just under $11 on Amazon.I got the Gelid Solutions Silent 5 Case Fan. From that change I have been using the scope even more. I haven't use FFT yet so my thanks for another cool thing to try. btw: How is Mom doing?? Rick

[@learnelectronics]

Cook I'll check that out

[@jackietrove4637]

Appreciate the video. Can I display the same things displayed here with a hantek 5102p (UPDATE: Checked out your video on the 5102 and it seems it lacks FFT functionality)? Also, what are cheap USB scopes like the handtek 6022BE missing that prevents them from displaying data this way?

[@pleaseyourselfsir]

I love the finer details being explained on the oscilloscope , ( turns me on ) - thoroughly ! As PhotoInduction would say : I aint having it , I want mmooorrrreeeee ! 🧐🇬🇧👍🏻❤️

[@TheTrueVoiceOfReason]

Hey Paul!! Would you possibly be interested in expanding on the functionality of the square wave generator (okay, 555 timer) into a more versatile "function generator", one that could include Square ('natch ;) ), Sawtooth, Triangle, and Sine waves? There's a kit somewhere out there ("beyond the pale moonlight..." Go away Fievel!) a number of years ago. I think I have the schematic somewhere. There are a number of 2 or 3 function kits out there from the Pacific areas, but no 4 function kits, at least not the last time I looked.EDIT: Found the Schematic. I believe that is the actual kit number.www.radiosparks.com/images_d/MK105D.gif

[@bblod4896]

Do you think the FFT would work in high frequency? 0 to 30 MHz? A poor man's spectrum analyzer?

[@learnelectronics]

Yes, this scope is good to about 100MHz

[@bblod4896]

@@learnelectronics DJ Paul....Can I put in for a request: Snip off a piece of RF on your transceiver so us minions can see sidebands on AM and second harmonics?

[@rrowan327]

Slightly off topic from this video. I believe you said in the past you developed power supplies. I was wondering if you ever use a dip voltage regulator LM723? I picked up a few to play with. Cheers Rick

[@learnelectronics]

No, mostly 78xc and 79xx regulators

[@shaknit]

A little off topic and I don't want to start a controversy but have you ever heard of the so called Stan Meyer step charge pulse or ever tried to recreate it. I know there's a lot of BS out there along with some truth. Your thoughts.

[@learnelectronics]

No but I'll look him up

[@shaknit]

He has numurous patents and died in 1996 the claims are that he was poisoned by big oil and big auto. More conspiracy theories. Claimed he ran his vw dune buggy on hydrogen from water produce by what he called voltrolysis not related to faradays electrolysis.

[@redfishervictoria]

Would you mind doing a video using the 4046 PLL VCO to show how it locks into a resonance frequency?

[@learnelectronics]

I'm not familiar with that IC, but I'll get one and see...

[@redfishervictoria]

learnelectronics I can send you some chips

[@GeorgeJFW]

👍