What is an op amp? Operational Amplifier tutorial & super spy microphone circuit

[@Afrotechmods]

Interested in learning about wireless power? Check out this course I teach: www.udemy.com/wireless-power-to-the-people-wireless-charging-101/?couponCode=KZbin

[@daggawagga]

Thank you!! I didn't even plan on learning this subject but it was just too interesting to pass up. Btw, do you plan on creating more Udemy courses?

[@Bryan514]

No electronics tutorial is complete without cats.

[@bonbonpony]

+Bryan514 Now it's time for the cat to be a part of some circuit :D

[@OmkarJadhav999]

yeah

[@JavierPortillo1]

Let's plug a cat to the mains! :D

[@GoldenGrenadier]

I'd hate to see a cat on photonicinductions channel. "Till she pops" he'd say.

[@EdgarsLS]

it's just common sense!

[@Afrotechmods]

@alpha001ful Lower resistances means more current needs to be drawn and that's easily avoidable. And a small signal op amp can't deliver enough current to power things like a fan.

[@Culturedropout]

Between you and Great Scott, I've learned more in a few days than I picked up from several semesters worth of college EE courses. Only about 40 years late.

[@dr.g7898]

As usual, your video is the BEST. For all the naysayers about universities, I use your video in my classrooms, from AC/DC onwards. And build the circuits you talk about. Thanks Again. YOU ROCK!!!

[@Afrotechmods]

@bcsupport Totally! But not the op amp I used. You would want a high speed buffering amplifier. Analog Devices, Linear Technology, National Semiconductor and Texas Instruments are good places to start looking.

[@FutureAIDev2015]

I like your use of cats!

[@Kj16V]

There are plenty of tutorials on opamp theory around, but this is the first one I've found that actually take a PRACTICAL approach - the only approach I can understand! Thank you and your technical afro!!

[@Afrotechmods]

@davidenelson Contrary to what is presented in this video, the better volume control circuit would be to have a fixed gain amp (e.g. gain of 10 to 20) and then use a potentiometer to divide down the input voltage.

[@Afrotechmods]

@mdesm2005 Yup. 9V batteries have significant internal resistance.

[@Afrotechmods]

@alpha001ful An op amp is just totally the wrong thing for powering a fan - you want a proper motor speed controller, h bridge, pwm circuit, or something else.

[@Air3gg]

I'm so amazed how this video is 6 years old, yet the quality is so on point! Great job!

[@alperenyurdakul1464]

I'm so amazed how this comment is 4 years old and how this video is 10 years old, yet the quality is so on point! Great job!

[@Abduls_lab]

@@alperenyurdakul1464 I'm so amazed how this comment is 2 years old and the heading comment 6 years old while the video is 12 years old, but it is still good and clear as the one made today

[@Afrotechmods]

@TheGuyInUrCloset It would be the best to have a fixed gain of 10-20 or whatever and then have the pot at the input of the amp.

[@otbway]

Engineering class at university would have been soooo fun if it was though like that...with actual real life application of an op amp, instead of hours and hours of solving complicate problems that you'll never see in real life....

[@danns87]

otbway So true... might have ventured more deeply into HW instead of sticking to SW as I ended up doing. Now, years later, as I'm messing around with electronics in my free time I'm starting to recollect some things I learned, and all of a sudden they're no longer drab, boring symbols on a piece of paper - they're something tangible and useful.

[@ioncasu1993]

just dont go to university and dont try to learn anything, cuz we all eventually die so its useless.

[@oukid2633]

Feels existential crisis man

[@ioncasu1993]

" instead of hours and hours of solving complicate problems that you'll never see in real life..." hahahahaha roflt omfg you're such a noob hahahahahha im literally rofling....

[@___xyz___]

Guys, look! Maxwell is trying too hard to become a meme again.

[@amoghgajare2581]

I loved the explanation you gave and that cat is so cute!

[@Afrotechmods]

+Amogh Gajare Meow

[@musicamex]

your tutorials are brilliant, distilled and humorous. i intend to watch them all. electronics don't have to be snooze inducing or overly complex and you are switching on the most important switch of all. the "i can" switch. i explain this stuff to my music students and your tutorials will become part of the homework. you are a gifted teacher. kudos. keep up the flow bro---

[@TrueMentorGuidingMoonlight]

Out of all the "Interesting Fact" videos I've watched for ECE207 prelabs, this is my favorite one.

[@Afrotechmods]

Which school?

[@pedromartinezlopez]

Purdue University, Boiler Up!

[@Afrotechmods]

Crazy. I had no idea my stuff is being shown in Purdue.

[@Afrotechmods]

@hyperboogie Normally the resistor is needed to set the cutoff frequency but in this case it's also essential because it acts as a pulldown to ground, so the signal ends up swinging from -10mV to +10mV. If all you have is a capacitor sometimes the output floats around DC biases you aren't expecting.

[@citizenalex1934]

I will nominate this video as a BEST OP-AMP TUTORIAL VIDEO AWARD!!!

[@Afrotechmods]

I will nominate this comment as the creme de la creme of comments!

[@BrokenCapo]

dude, u have the best tutorial... quick and concise, easy to understand, and entertaining and funny to boot. love it

[@CREE8CHANGE]

Hey man- just wanted to say thank you for your videos. You really have a wonderful gift of easily explaining things. I watch some of your videos, on concepts I've struggled to grasp for a long time, and then it just clicks. Thanks for sharing your knowledge. Keep them coming!!

[@Afrotechmods]

@Knightmetal It should be the same ground i.e. they are connected somehow.

[@crossbones911]

Perfect. I was thinking about getting into electronics this summer and it looks like I'll be using your videos. Teach me your ways sensei

[@alexvalent2176]

haha same

[@stevenchiverton48]

a circuit i built once before was a 4 mile mike and its super sensitivity and amazing gain makes it so sensitive it can hear the most tiniest whisper you can ever make 14 feet away and around the corner of a wall and thats amazing, the sound of my tiniest whisper is beyond faint, which means i have to have my mouth right in your ear so you can just hear it so with this circuit 14 feet away that would be considered impossible but it worked im recreating this circuit again , the circuit used 1m5 potentiometers which ive found dont exist online anywhere not even e bay so i had to make some changes hoping it would work but despite the feedback squealy it worked beyond what i expected . and i had to adjust it to reduce the feedback to the edge so its at the beginning

[@rlrsk8r1]

So I just built this circuit with a gain of 11, using a voltage divider to give me +9, -9 and 0 volts from an 18V supply, and I hooked it up to my Raspberry Pi's audio jack. Then I played this video on the Pi, piping the instructions on how to build this amp, through this amp. Recursion is fun.

[@LNTutorialsNL]

I'm Dutch and 14 yo, and the subs help me a lot with understanding everything you say. Thank you!

[@simbaliya]

A question here, in the schematic @ 03:15, I think between R1 and ground there should be a capacitor to block GND level from negative feedback network.

[@VallabhaHampiholi]

Seriously who have disliked this video? That was an excellent video depicting all the important stuff about Op-Amps.

[@cerkit-creative]

OK, this has to be THE BEST electronics tutorial I have ever seen. "And you only have to use...as many as you want". Classic. It's also 100% KZbin compliant because it has a cat in it. Oh, and I learned what I cam here to learn.

[@shutdahellup69420]

5:10 she was like "wait...dafuk is dis bullshit...ima eat it" XD

[@christaylor8142]

Awesome explanation. Made complete sense the whole way through. The theoretical side with the schematic explained and then the demonstration at the end. Mint. Subscribed

[@LT89NL]

Just the cat alone already makes this vid awesome, not to mention the actual information, which is already really well explained and clear. Thanks for uploading it!

[@agentgates]

Hi, thanks for sharing this video. This is what I was looking for! I've got tired in the harsh theoretical lectures without basics. Finally something that I can use after first watch. :)

[@KelvneMachado]

This is the best video to introduce op amps I’ve ever watched

[@masouddayaghi5923]

I watched tons of videos about op amps and never got it, just now I got it, it was with a big distance the best viedo I have ever seen in this topic, thanks a lot.

[@Afrotechmods]

@Anathor666 It could be anywhere from 100 ohms to 1 meg - I just found by experimentation that 5k gave me the biggest signal and resistances lower than that didn't give me any extra benefit.

[@snappex]

I just made this and most of what I was getting was the local radio-station... :) Thanks for a great tutorial and keep making awesome videos!

[@EddieVanHalen1977]

You have helped me learn a lot. Thank you. In fact, I think I have learned more from your electronics videos than from anyone else's videos by far.

[@georgezanfir]

i just wanna say THANKS dude !!!! you save my project with this vedeo :D

[@ForViewingOnly]

Simply the best tutorial/refresher videos on KZbin. Thanks Afrotechmodman.

[@amseek94]

By far the easiest to understand and straight forward tutorial on op amps I've seen yet. Thank you! Couple questions though: - Using the 9v+9v power supply circuit in this video, is the center point GND (0v) fron that circuit to be used as GND for everything else that connects to GND in the rest of the circuit? Just wasn't sure how to connect the two circuits together. - I'm using a 4580D (JRC) dual op amp. It's voltage range is 2v-18v Should. that still work? I haven't gotten this to work yet, but I am using salvaged parts so it might be a messed up part somewhere. Again thanks for your great videos. It's super refreshing to have such good explanations 😁

[@Afrotechmods]

1) Yes GND connects to GND 2) Yeah I think it will work

[@cougalways]

Bush wiretapping is not political, it is historical and I think he would be alientaing about 15%. Thanks afrotechs! Your stuff is the best, humor and all. I really appreciate all the effort.

[@martinest9458]

Literally the first tutorial where i get how the op amp works. Thank You !

[@boy_deploy]

Featuring AfrotechCat... 😄😄😄 Nice video man 👍 love your tutorials

[@doodh_jalebi]

it has been 5 months and i couldn't understand these things! YOU ROCK!!!

[@Afrotechmods]

@nlimchua The equation is correct because R1 is 1000 ohms.

[@kamaleldinmohamed1702]

dude, you cant imagine how much thankful I am

[@christophercanal4]

Fantastic Video! I'm an Electrical Engineering Student, and you just cleared up so many questions for me. Thank you.

[@MrChannnnnnnnnnnnnnn]

In less than one minute, I was able to understand the use of opamps! thanks!

[@4dirt2racer0]

jesus man once again youve taught me something extremely important that iv been trying to confidently n comfortably understand for years which is negative voltage, iv had a pretty good understanding of it but iv never really had a good "feel" for it.. idk how else to explain it thanks so much i wish i found this video 10 years ago lol

[@danielsalloum3006]

You make me feel geniousish with every video. So addicting.

[@isfiyiywafibc6qaiiiiiiiiii570]

The theory behind op amps is actually really interesting.

[@Xempt_One]

good circuit, the ones we built in electronics were twin output amplifiers, very simple to make, a few caps a couple resistors and the IC

[@guzziventure1750]

You're so good! Unbelievable great to listen and watch your video's. Impossible to express how great they are.

[@Afrotechmods]

+Guzzi venture Thanks!

[@m.a.2169]

You're so awesome! Please keep doing these they're so fun to watch and straight to the point (:

[@erichoogstoel9417]

cat noises amplified > ASMR

[@Afrotechmods]

cat noises > EVERYTHING

[@HKCREATESUNIQUE]

Afrotech mods. Why you are not making videos now

[@longchaojia1040]

WOW This explanation of amplifier is amazing. Easy to understand and funny all the way.

[@randywatson8347]

Nice video. I hope to know more about how single supply opamps work when it's single battery operated

[@doominc]

I could literally watch these videos non-stop

[@virgill6881]

Why is it better to adjust the volume after the amplification, and not adjusting the value of one of the resistors that are setting the gain? Is is because if you adjust it after you can get 0 volume, but while adjusting the gain you can't? Great video!

[@mg3byte]

+Litan Virgil If you play with the gain before amplification with regards to lowering and increasing volume, the signal would be distorted and noisy due to variations in frequency bandwidth. Hence it must remain stable for the output to be smooth.

[@djryanashton]

At 3:08: why do you need a circuit to power the microphone? I thought that's what the job of the Op Amp is: to boost the 0.02V to 2V? And then why does the power to power the microphone need that 5K resistor?

[@shutdahellup69420]

op amp itself is a circuit

[@djryanashton]

That doesn't answer my question in the slightest.

[@xhivo97]

Ryan Ashton It limits the current, so that the microphone does not blow its brains out .

[@djryanashton]

Thanks :)

[@areg7182]

The microphone is a capacitive type, which means it does not output a voltage, but acts like a variable capacitor.

[@seasonedtoker]

Mr. Afro, if I understand these amp circuits corretly, it would take two chips for stereo output, right? one for each channel? thanks! your vids are a blast

[@christianmarquez3143]

That was really cool. I like how you demonstrated something that we can really use and really put together. Thank you!

[@manamixingup]

Hello, can you explain why the resistors for the gain must be in the kilo ohms? I mean, we can get similar gain with lower values of ,resistors. So why use in the kilo ohm range??

[@manamixingup]

+fo shizzle thanks for the reply, it's clearer now :)

[@AlessioBalsini]

The ground is connected to the middle of the batteries series, as shown at 1:40. The 9V output of the power supply goes to pin 4, as -9V to pin 11 of the LM324 shown at 3:29. This whole configuuration is to keep the output signal oscillating symmetrically with respect to the ground reference (I mean, with a 0V input, the output will be 0V too).

[@zynthos9]

What allows one op amp to deliver more current than another? Also how did you know the amount of current appropriate to feed into your headphones to make them work properly? Did you test this at the same time you tested to find out that the signal on properly functioning headphones is about +-2V?

[@reehji]

+Zambia95 your speaker is just a load, and it should has a spec somewhere that says you can't run over x amount of mA or it will fry up. For +- 2V i'm not too sure...you want to have enough supply so that the output won't get clipped off, so it's all depend on your output voltage and the following variable resistor.

[@zynthos9]

Reehji When you say speaker do you mean the headphones? I don't see any part numbers or anything like that on most headphones that could be used to find a datasheet.

[@reehji]

***** it can be anything. but i used a cheap speaker. Not sure how the quality with headphones/earphones would be. Here's a speaker i used in a lab /watch?v=clE5xVppiDE

[@marioarchibald4712]

Why is the positive power supply on the side of the non inverting terminal and the negative power supply on the side of the inverting terminal in the op amp circuits? Shouldn't it be the other way around? Great video though!😀

[@vincezzz9757]

Very clear and help me understand how op-amp works. Great video!

[@catalin3407]

At 5:03, could anyone tell me what is the function of C2 ?

[@retrohd1_]

Time stamp: 1:35 Why put capacitors in parallel with the battery output? It's already DC. What is it filtering here?

[@danielallan5058]

haha 'clipping would mess a lot of things up"..clipping is why I am here!!...(op amps for fuzz pedal),

[@jack002tuber]

Me too. Whenever I think about op amps I think about clipping and fuzz pedals!

[@SirDella]

Every amp that I make with battery Power clips, do you want it? Lol

[@Landotter1]

@Shoyrou If you do a split power supply eg +9V and -9V Ground is for signal ground only. Tie all GND parts together and that becomes the (-) of your signal. If you use a single supply, +9V, the grounds go to the (-) on the battery. Notice the power amp he uses has a single supply. Tie the signal ground from your op amp to the ground of the power amp, and the (+) output of your op amp to the (+) input of the power amp. Good luck!

[@maseay91]

awesome. I've always wondered.. how is audio collected by a microphone and turned into a voltage ?

[@TheHuesSciTech]

Great video. It's worth noting, though, that using a split supply (i.e., two separate batteries) is completely unnecessary. Take out one battery and just add a couple extra resistors to bias your signal somewhere near 4.5V, and viola. Still heaps of power for earphones. I know the author was keeping it simple for pedagogical purposes, which is fine, but I wouldn't want people to watch this video and then go and actually start making two-battery amplifiers... Google "single supply op-amp" for more details; most battery-operated circuits will work this way.

[@Starbuckin]

I always use single supply with my Op Amps!

[@ubuntututorials]

@samanthms123 It would, but you wouldn't be able to see much because the blinking would be too fast. You might be able to see the high and low parts of the sound.

[@Stogoh]

Can I use a Potentiometer to change the gain of the OP-AWP for changing the output voltage? Should work, right?

[@maykelfarronay]

this may be a stupid question, but does the input source have to be ac? can it also be DC to multiply the voltage ?

[@petegabler9528]

Seriously your tuts are gr8 and so is your Sulu impersonation : )

[@mi626]

Low impedance means low "ac resistance" so it is a heavy load for the frequencies of interest that will force/cause the source to provide more current the source may or may not be able to provide. An 8ohm std speaker for example would be too heavy of a load, presenting a too low of an impedance for LM324 can drive.

[@seasonedtoker]

sorry, I think the video itself explains it. if the chip has multiple opamps, you can send both channel through the same chip

[@jpandresaguirre]

Encouraged by your video I´ve made the circuit. I have a problem, When I disconnect the batterys common terminal to GROUND, it works perfectly, but it stops working as soon as I make that connection. THANK YOU! It's a very good video.

[@jimmyshakway2737]

at 1:40 wouldnt that just be 0v, 9v and 18v? since theres not actually such a thing as positive voltage

[@tomjohnsonboronmandela8107]

Jimmy Shakway if we take the 9v as ground (0v), the 0v appears to be -9v. voltages are relative. it's sort of like if i take the 50th floor of a tower as my "ground floor", and someone else is standing on the 45th floor, be appears to be standing 5 floors below "ground floor"

[@jimmyshakway2737]

but you're still on the 50th floor, and floor 1 is still ground in reality. The same would be true for electrons since they are always negative, there should only be a lack of electrons (+) and then surplus (-) that only goes up and never below +. assuming your building doesn't have a basement lol

[@NoFear4XJs]

You should put together a DIY package for the 2, 9 volt battery version. Would make it more inviting for people that are curious enough to think about it but get lost or discouraged when looking for the parts. If you do include a mic jack and a speaker wire output clamp. Would also be great to see one for an mp3 stereo amp with stereo speaker wire clamps, for this if I was you I would go for quality sound over a price savings of a $20 dollars.. Thanks again for another great video, Cheers

[@learnerlearns]

Toaster oven ding = brain done. Best laugh I've had today! Thank you!

[@andreasrerres3651]

Hello. You are so good. I built your project but I have sound only in blow molding the microphone. And the sound is low. What i am doing wrong?

[@jaredevans8518]

Do all circuit grounds go to the ground of the power supply?

[@MultiSchuman]

great video my friend. most informative. i was amazed you posted this in 2009. you are doing world a great service. thanks you again. keep up the good work.

[@Juan.Jose.Jaramillo]

its nice how easy you put words so we can understand.

[@PietroGazda]

Thanks, I'll think about it. I still have it on solderless breadboard trying to add more features (switch to gain change, power switch and LED etc) before putting it in box

[@mrchiccolatte]

Hi Afrotechmods, when can you have a new video tutorial? I've been waiting it. You're a big help to electronic beginners.

[@marciokoko1]

Gr8 explanations. Do you have videos for explaining voltage regulators, lm317 and lm7805?

[@OmkarJadhav999]

Finely explained, grateful !..and the cat adds up to the presentation, adorable.. ; )

[@richards8827]

Nice diagram showing how to create a duel power supply.

[@mitchellbenoit3689]

Can you tell me what the 5K resistor is for that is connected to the +9V input?

[@jstro-hobbytech]

Your videos are great brother. I find it funny how you started out with an old owon and now you've got that nice free keysight they give all the channels that get a good following. Not an insult. You deserve it and it really ups your video quality.

[@johnbattaglia6369]

Great balance of info and humor. Love the cat at the very end!

[@ninolouieverame3591]

can you help me with my noise level detector? is it good to use op amp? and I really need a good schematic, if you have the time. Thank you in advance

[@FantaBH]

I have seen your comment on Great Scot channel last night and that brought me to your channel, , still exploring it but so far , you are good and it worth sub. Nice job.

[@tziirkq]

I'm having a hard time finding out how to power an op amp with a single 9v, specifically for effects pedals. Any chance you might be able to shine some light?

[@PanCakeMixer101]

hello this might sound stupid but I am attempting to build a vinyl player for a home project, can I use an OP Amp to amplify the signal from the stylus before feeding it to a stereo amplifier?