Classic Circuits You Should Know Relaxation Oscillator

Classic Circuits You Should Know Relaxation Oscillator
In this video we use an opamp to create a simple relaxation oscillator.
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HEY YOU ABOUT TO POST SOMETHING STUPID:
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One of the symptoms is that is causes fluid retention, mostly in the hands, feet/ankles, and face.
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Light Meter Smart Sensor AS803 amzn.to/2B2gyRg

[@opalprestonshirley1700]

Yep, an op-amp is an analog device. Great little oscillator. Thanks Paul.

[@simonowen488]

Your signing-off words were well delivered and hopefully heard by the right ears. I've been learning from your channel for a good while now and I'd like to thank you for the University-level content without the University clutter or pretension and the 'lo-fi' format that's clear and understandable and free of pretence or arrogance. Keep it up and thank you.

[@jonathansera6134]

Love your Classic Circuits series. I'm sorry you have to write such declaimers on your description. BTW I think an Op-amp is totally an analog device.

[@MRPINKBALLS12]

Honestly this is one of the best electronics channels on KZbin as far as I'm concerned, I'm trying to learn an I really appreciate people like you who take the time to do these videos Thanks! And also you do a great job explaining things.

[@ibnewton8951]

Regardless of whether it is analog or digital, it *_IS_* an integrated circuit. 😉

[@tanksniper380]

Did what my Uni professor couldn't - amazing

[@ChadKapper]

I appreciate all of your videos!... anyone making negative comments is just unhappy and insecure. Thank you for your all your hard work!

[@morik3188]

Loved hearing your parting words. There will always be nay sayers. The amount of knowledge and teaching you bring to the table is enough to put any hater in their place. I'm new to the hobby and value these videos immensely. Thank you for all the work you have done.

[@cw4608]

Good for you! I am so sick of the Whiney-ass comments from the haters! Thank you for the time and effort put into these videos, 90.1K subscribers also thank you.

[@hydrostatics]

Love your channel bro, All your diagrams work so well

[@attifhiffnie9433]

Man , you rock . You make electronics as general looks more fun , simple , and proffecional . Please keep doing it ...

[@mikeoliver3254]

The classic circuits we should know are my favorite series of videos you do. They are always fantastic videos Paul. I thank you for all you do for our little community.

[@davidluther3408]

I AGREE!

[@StationGarageSt]

uk auto mechanic here........as cars now have more in common with Mr Kirchhoff than Mr Ford and also that most car techs still struggle with Mr Ohm and his pal Mr Voltaire and car electronics go bad all day every day I find your videos give me a distinct diagnostic edge. To quote "scannerdanner" pulling codes and fitting parts IS NOT diagnostics. Everything I learn gets passed on to the rest of my team. Great teaching. Love to see you reverse engineer something like a wash/wipe function relay. e.g 4b0955531c .....vw/audi.

[@learnelectronics]

Thank you. Its nice to know I helped

[@philowen2755]

I really enjoy this series. Once again, many thanks Paul.

[@anthonyselby8337]

Another great video on classic circuits many thanks and keep up the good work

[@paul-c7541]

I love the basic must know circuits Paul, it's been a very long time since I went to Technical college, as part of my apprenticeship in a TV/Radio repair shop. I had forgotten many of these circuits, the reminder also reminds me of very happy days, now where's that time machine so I can go back for a while.

[@andyjohnson4485]

You are an invaluable source of info for an electronics hack like me. Love your channel Paul!

[@LitesLAB]

Great job Paul! This is a great start for anyone looking to create a Tremolo pedal :)

[@lambertsimnelales5878]

I thoroughly appreciate all of the content that you provide to us for free, I find it to be both educational as well as entertaining. Unfortunately there are always those would would rather gripe than be thankful. Cheers

[@hughatkins]

Thanks for these videos, they are great! The op amp is analog, and I appreciate what you do.

[@enigmaflyonthewall515]

Thank you for your work

[@baldrickdaisy8982]

Thanks Paul for another classic circuit lesson. Awesome!

[@michaelhyde9971]

Thanks for all the hard work.

[@SomeGuyInSandy]

Looks simple and easy to learn from. I will give it a go, thanks!

[@largepimping]

About the comments at 11:26 - until about a year ago, HBO was also producing episodes of Game of Thrones "just to keep their channel going." I understand that there are always people out there that are just dying to find something to be negative about, but this, to be charitable, is just WEIRD. So yeah, thank you for making content that people find interesting and helpful... just to keep your channel going [ «smiley» ].

[@GM-vk8jw]

Without people like you sharing their knowledge about electronics then people like me would struggle learning the practical elements from a book. I wouldn’t mind standing to a buck a month. Dude I’m in 🙏

[@ameenwaheed268]

Thank you Paul for the amazing videos. I wish there was such a channel when I was young.. Too old now and yet find your videos very interesting.. Thank you again.

[@utkf16]

Im in the same boat Ameen

[@HappyHands.]

Good fade on and off. Handy when mimicking old strobe bulbs

[@crohkorthreetoes3821]

That last part got my like. Thanks for sharing the knowledge.

[@PnPModular]

Excellent "down to earth" video thanks mate

[@azertyQ]

It would be nice to see those drawn waveforms on the oscilloscope on the completed circuit

[@veritasaequitas9875]

I'm glad I came accross this. Thanks to the author. I'm on a mission to see how many ways I can make an LED flash on and off. (Other than buying flashing LEDs from ebay). Why? Because it's a good way to get to know what's going on at the component level. Figuring it out from basic principles. This will be #4. Just ordered some op amps.

[@utkf16]

Top channel for learning the art of electronics thanks Paul

[@learnelectronics]

Wow, thank you. I appreciate that

[@tedbastwock3810]

I thought op amps were analog by definition, but wth do I know lol. Love this series.

[@seditiousmonkeyart]

Thank you for sharing you knowledge and expertise. Personally I have learned so much from this channel in the past year. It would have cost me thousands of dollars to learn at a college.

[@robertfenney]

Thanks you do a great job!

[@neilfurby555]

Really great approach, and non intimidating... super stuff. Thanks.

[@oo0Spyder0oo]

I put a similar circuit into a home made tardis for my son years ago, keeps the roof led cycling as per the tv series.

[@BADALICE]

I like it. I have made several flashers with transistors that switch back and forth, every USB port in the house has one. I like them, as you said they are soothing. I like the fade effect of this circuit. What I would like to do is combine the properties of both. PS I just finished building my DIY power supply, and it only goes to 12V. I'm not ready to build another one just yet. Some of the flashers I made I added fiber optics, to make little 4, 5, 6" blasts, or showers, they turned out nice.

[@acmefixer1]

An opamp is an analog device, but here it's being used as a comparator. Since the output of a comparator is always a high or a low, it's not linear output, like a normal opamp. But the output of a comparator is typically +5V or 0V, not + or - 15V. So this seems to be outside of either digital or analog worlds.

[@ErazedFX]

I am really into synths and stuffs , thanks for the video! Would you consider making a follow up video to turn this into a voltage controlled one?

[@erygion]

Great circuit Paul, I had fun. 😊 I would say (in this case) it's analog. I can't believe people say mean stuff like that, it's the internet so I guess I can believe it but still. I love your videos and especially the "classic circuits you should know" series and I've been with you for almost 2 years and have learned a bunch, thank you.

[@michaelpadovani9566]

Awesome video and good to know circuit. I consider an opamp both digital and analog. The input is [usually] analog but the output is digital.

[@incompetentlogistics]

Thank you for your great videos. As someone who is watching your channel mainly for dwelling into creating my own basic synthesizers, it would be useful to learn how to control the frequency (with a potentiometer) with these oscillators you''re showing off. I hope that's not a dumb request!

[@CTCTraining1]

Very clear and concise, much appreciated. Might make for some interesting plots on the scope?

[@anthonymiller4703]

Thanks for another excellent upload. I am compelled to say that it is un-nerving to hear about the criticism of your videos and how the internet's finest seems to have taken them for granted. I would just like to point out that your videos in my opinion are practical and have been very useful to me and others and a lot of fun to boot! I plan to upload a video of the 556 application that you posted and how I made use of it, I never liked working with the dual-timer until I built the circuit that you posted here, some nice modulations and killer views when I scoped it.

[@jon00200]

Thanks sir!!!

[@theengineer9910]

Nice! I could never get any op amp oscillators to work for my regulator so I did a transistor one instead but I'll give this a try !

[@mohammedalathari9635]

Thank you, I'm learning a lot and I like your approach. 1. please don't pay much attention to some negative comments, and as you said let them show us what they've done? Is it any near dedicating one's self for four years so far to make free electronics lessons? I would say probably not! 2. I think analog with not much doubt. 3. where is the oscilloscope part! I was little like 😞 I really wanted to see how the wave form would look like in the real life!

[@maks886]

How about using the second op amp that is in the chip, configured as a comparator to get the output closer to a proper squarewave?

[@kenlanier2131]

Nice closing comments Paul! I know I am one of many people that really appreciate your videos. The Losers who have negative comments are probably so disappointed with their own lives that they have nothing better to do but to ignore there own pain and try and find fault with others. Pittiful,,,, :) Please keep doing what your doing! The sain people out there enjoy it! -Ken

[@louchitchat]

Love your serries

[@ku4nz]

Only thing I would say is: Thanks for being great teacher

[@mightymulatto3000]

The main purpose of ICs originally were to make analog circuits smaller and more reliable. Op amp ICs are used in a variery of analog applications. Op amps aren't inherently digital by themselves as none of the required components are in it's package. That said Op Amps are in other IC packages that have digital functionality.

[@Enigma758]

If you consider the gain equation (g = Rf/Rin) for an inverting op amp, it provides a way of thinking about how this works. Rf = 15k, Rin is the resistance of the capacitor. Initially, when the capacitor is uncharged, the resistance is very low so the gain is high which charges the capacitor. As the capacitor charges, it's resistance increases until it effectively becomes an open circuit. At that point the gain is close to zero so the capacitor can then discharge. Then the cycle repeats.

[@weerobot]

Awesome....again...

[@markclark787]

Thanks

[@jaredgray7872]

I think what you were trying to say is that the only way you can write code with this circuit is with solder.. not a μC

[@hibridorenergialibre9481]

Hello. Is it possible to make a relaxation oscillator with a varistor? If so, I would like you to make a video. Thank you for sharing such valuable information on your KZbin channel.

[@rfc1180]

yessir; good job! Yes, an analog device!

[@ozzymandius666]

Is there a formula for the frequency based on the capacitance and input voltage?

[@frankowalker4662]

Great vid, always learn something. Loved your comment to the nay-sayers, Classic. :)

[@wishicouldarduino8880]

Awsome!😁👍🛸🤖

[@user001sg9]

Nice video. Thanks. One question though, if I were to connect a loudspeaker or a buzzer instead of the LED shown in your circuit, would a simple NPN transistor like BC107 or BC547 would be sufficient as a current amplifier?

[@learnelectronics]

Sure

[@ed-jf3xh]

What's it look like on a scope?

[@oscarmendez590]

Thanks for the classic circuit videos. I attempt to duplicate every one.

[@musiquerelaxationnature2337]

❤️❤️❤️❤️❤️❤️❤️❤️❤️Salut super video merci beaucoup ❤️❤️❤️❤️❤️❤️

[@GORF_EMPIRE]

More Oscillators! Oscillators make the world go 'round.....

[@georgechambers3197]

Isn't it kind of half of each digital and analog? Cool circuit a real classic. 😁 Thanks for the video!

[@learnelectronics]

I would say that it is open to interpretation.

[@notoriouselwood9253]

Dude! 🤙 I are hooked. I’ve been a closet electro-hole forever. But, now? I’m thinking that I’m thinking 🤔. And i like it.

[@nigeljohnson9820]

All devices are really analogue. In this case the op-amp is being used in limit mode, making it function as a digital device. The relaxation oscillator could have been implemented by a comparator, or my favourite IC the quad nAnd Schmitt trigger. The latter would only have required two components to make it oscillate, an R and a C. as the switching voltage threshold is set by internal resistors in the IC, making the actual values dependent on the logic family used. One advantage of using a quad Schmitt logic device for this circuit is that it can implement up to four independent oscillators, or make the oscillators interact to give a multi tone output or provide a cadence on one or more tones. This is very useful if you want to make an alarm output. The HCmos devices can safely drive a medium impedance speaker (300 ohms) directly, to give a useful sound level output. If more output is required, just add a switching MOSFET to the output to drive a low impedance speaker. It's not difficult to add an LED output, so that not only does it generate an alarm tone, but it also flashes an LED in sync.

[@tomaszwota1465]

That sounds like you could make music with it. But if this could be used to generate a single tone, and I'd like to have each key to generate different tones/notes but have all of them still be "modable"... I'd have to modify it later using filters and such, right? Or... Maybe I could use two oscillators per key with their own RC to have base tones and use the two that are left with common adjustable RC to change the sound that way. Now I'm kind of interested how that would sound. Am I far off the general idea?

[@davidluther3408]

I REMEMBER A EXAM QUESTION IN COLLEGE ASK WHAT ARE THE CONDITIONS FOR OSCILLATION?OF COURSE IT WAS THE BARKENHAUSEN CRITERIA FOR OSCILLATION STATING BA=1 AND THE CIRCUIT HAS 0 PHASE SHIFT.

[@ismailtan]

What if you don't have or want to make use of 2 power sources? Is there a way to "split" 1 power source into two (negative voltage and positive voltage)?

[@tomaszwota1465]

I'm sure by the time you're reading this you know it already, but yes, you can do it. Even a simple voltage divider will do, with "virtual ground" on the middle.

[@bengriffin1878]

I tested this same circuit through simulation. it gave me a lot of different results, some were step functions, some were other stuff. None of them gave a square wave unfortunately. What is going on? I know the circuit built was right (you confirmed it experimentally), but why am I getting a deviant value?

[@mychevysparkevdidntcatchfi1489]

If it's square wave output, shouldn't the LED be sharp on/off instead of slow fade on/off as in video?

[@learnelectronics]

It is NOT square. It is sawtooth, the classic charge/discharge of a capacitor.

[@MalagasOnFire]

Simple oscillator and yet efective for understanding its principle. It uses the opamp and books describes as analog IC . If using all analog circuits, it is not "cheating" aka use a digital instead and break the principle.

[@kolinevans9127]

I’d like to think everything is analog, but I guess it’s probably not the case? great video, just for clarification for others watching can we say you used the two different power supply ‘+’ and ‘-‘ connected them together forming a ‘neutral’ 0 V, then each alternate supply was 15v potential above and 15v potential below that 0 v ? Thanks for sharing, don’t mind the hayters this is Earth after all : D

[@vegtersbaas]

Paul, how can I create a negative voltage with my little 24v DPS5005 bench powersupply? I have only 1x DPS5005.

[@learnelectronics]

kzbin.info/www/bejne/inmze4GqlM-qZ7c

[@MarioAlemNeto]

I love these simple and useful circuits! Is it possible to turn that "pointy" waveform into a sinus?

[@nigeljohnson9820]

There are several ways of doing that. A simple low pass filter RC filter will turn the waveform to a sine wave, however it is necessary to engineer the cut frequency will below the frequency of oscillation, this is to ensure that all the higher harmonics are attenuated to just leave the fundamental sine wave frequency. Unfortunately, this reduces the sine wave amplitude, and makes the amplitude frequency dependent.

[@MarioAlemNeto]

@@nigeljohnson9820 thank you! If I then amplify the resulting sinus wave, will the attenuated harmonics be amplified back to the original signal?

[@nigeljohnson9820]

@@MarioAlemNeto no, the signal ratios will remain the same, provided you do not drive the amplifier into limiting. The same result can be achieved filtering a square wave, however it helps if the wave you are filtering is closer to being a sine wave in the first place. Mathematically, any periodic waveform can be constructed by the super position of an infinite series of harmonic sine waves of the correct amplitude and phase, this is known as Fourer analysis. All the filter is doing is removing the higher harmonics of the waveform, to leave the fundamental sine wave. if the filter was perfect, passing all frequencies below the cutoff and rejecting all above, a so called brick wall filter, it would not be necessary to engineer the cutoff frequency so far below the fundamental frequency of the wave form. As it is, the best that a simple RC filter can do is attenuate each harmonic by 6dB more than the previous one. This is because the filter attenuation slope, beyond cutoff, asymptotically approaches 6 dB per octave. So to obtain a good 6dB slope, the filter cutoff must be of the order of two octaves below the wanted frequency. To achieve better rejection of the higher frequency components requires a higher order filter. One that is a closer approximation to the ideal brick wall filter. That said, attenuating the higher harmonics will make the resulting waveform closer to that of a pure sine wave, and certainly more pleasing on the ear. If you really want a near pure sine wave, there are much better circuits for generating it.

[@MarioAlemNeto]

@@nigeljohnson9820 That was a great explanation! Thank you so much!

[@MrRobertBassett89]

Yet Another amazing video!, I have a single power supply that has a positive, Ground, and Negative outlets on it, Is this classic circuit still doable with my supply?

[@lucasc5622]

should do, i would poke it with a multimeter though to make sure you have the right voltages

[@Timsturbs]

yeah it works with a single power supply just add another resistor from +power to +input just tested

[@Timsturbs]

and by replacing R1 with potentiometer and a couple of diodes you can regulate on\off ratio thus making a simple pwm regulator

[@keithking1985]

my nephew told me about a light-house he's building in school in a couple of weeks. he was showed how to connect a battery to a bulb or LED today for it.. this circuit would be better.. i'll make it for him and he can use it instead!! P.S. i'll use a 9V battery and a voltage divider to power the op-amp!!! all he has to do is connect the battery to a 9V clip/snap i'll add to the circuit & wallah...

[@ryanbates362]

What determines the speed of the oscillation? Is it the value of the capacitor?

[@learnelectronics]

Yes, it's charge/discharge cycle which can be further regulated with a capacitor.

[@randomnameifyful]

how would you build that IC on a breadboard using simple components. i really like your channel, haters gonna hate they only win if you give them your time.

[@ae1tpa92gwtom2]

op amp, another building block component, as u say, allot simpler than a wide band opamp made from transisters, used to be 1 circuit board, next time put the scope on it, would be great, cheers n 73s

[@strayling1]

An op-amp isn't cheating, but using two bench power supplies is pushing it a bit :p Does the circuit really need that much voltage or could I use a couple of AA cells? Thanks for the video, fascinating as always. Think I'll revisit the op-amp stuff and see if I can join up the dots

[@Willam_J]

Technically, an Op-Amp is both analog and digital, depending on the application. This detail, is in the name of the device. “Operational Amplifier”. They can perform math operations, as well as being used as analog amplifiers. If you wanted to use them strictly for math operations, you would typically choose a Comparator, which is very closely related to an op-amp (and sometimes interchangeable), but better suited for math operations. It’s like asking if a transistor is analog or digital. Again, depending on the application, it can be either. It can be in an on state or off state, or it can be used in its linear region, which will produce a variable voltage or amplify a signal. Another point of interest, is that digital IC’s, such as logic inverters, make excellent oscillators. By tying the output to the input, it sets up an infinite loop of changing states. The frequency of which, can be controlled with a capacitor, a crystal or a resonator. In your application, it’s being used as an analog device. I believe that the differentiation you were trying to make, is whether the device can be used ‘as-is’, or if it needs code to be programmed into it, such as with an Arduino or PIC processor. In this application, it’s much easier (and less expensive) to simply use an op-amp, unless a more precise frequency control is needed.

[@anthonymiller4703]

I like you're technical commentary on the video but just to provide some clarity about our charitable instructor in the video above- he is also aware of the variations by application/definition, data-sheet info, etc. that you have pointed out, as I've heard all of the above points that you've highlighted spread out across many numerous videos that he has made and posted to this channel. When the man asks the question about the nature of the op-amp being analog or digital that is done for the benefit of the viewer; being geared more for the beginning learner while displaying extremely practical circuits that any level of hobbyist could find use for. Again, I appreciate your refined output- I hope that you can appreciate my 'positive-feedback' and the intended pun!

[@pulesjet]

Op Amps work in the Analog realm. Comparators in the Digital.

[@midnightrizer]

i agree an op amp is analog.

[@bob4analog]

Op amp is defintely an analog device. There's nothing digital about it, thus the term 'op amp.' 😉

[@johnmoor8839]

making vidios to keep your channel going is kind of required for a site that is for people to make vidios to put on their channel, i would have thought. unless ive totally got the wrong idea about youtube. could be me, but vidios do tend to crop up a bit. i wouldnt let it bother you, unless they have worked out how to have a vidio free youtube channel, then they might have a point but till then i think your ok.

[@michaelmounts1269]

It definitely is an analogue device...!

[@JahanZeb1976]

*Perfect dear sir. Excellent explanation. I'm also an engineering KZbinr.*

[@anwarigroup]

I think this IC gives Digital signal, not analog

[@grahambambrook313]

Thanks Paul, Good stuff for we newbies but I still don't understand why it's called a "relaxation" oscillator.

[@learnelectronics]

Just a different term for the discharge of the capacitor.

[@grahambambrook313]

@@learnelectronics Cheers Paul

[@mardav1545]

What makes an oscillator a relaxation oscillator?

[@djvanzz]

Would love an explanation of bipolar power supply theory. It still gives me trouble

[@mikeoliver3254]

Edward Ciotic if you take two similar power supply’s and hook the positive of one of the into the negative of the other and use that line as the ground line then the other positive will show n volts and the other negative will show -n volts. Hope this helps if you don’t have two power supplies you can hook up a couple of batteries the same way and use a multi meter to see what I’m talking about.

[@jtb8631]

opamp is clearly analog, I agree you did not use any digital devices, or even integrated circuits for that matter.

[@tomaszwota1465]

Well, an opamp is an integrated circuit. It's an analog device, but it's used here more like a digital device, since it's only either full on or off, the ramp is thanks to the capacitor.

[@timwsac]

Analog Paul

[@poochie1480]

Really appreciated .Please ignore the sad losers

[@aneeshprasobhan]

:)