LM386 Audio Amplifier Simple Setup

LM386 Audio Amplifier Simple Setup
In this video we setup an LM386 using the application data from the data sheet. At first there is now sound, but it just starts working. Who knows why? Wonky Chinesium knock-off IC? Moon in the wrong place?
5 boards for about $22 in about 7 days www.pcbway.com
Yes!! I now have merch: teespring.com/stores/learnele... Electronics themed T-Shirts!
HEY YOU ABOUT TO POST SOMETHING STUPID:
Yes, I know my hands are large/fat. It's because of a heart condition I suffer from called Congestive Heart Failure. Here's a link to some information about CHF: cle.clinic/2TdS2Ux
One of the symptoms is that is causes fluid retention, mostly in the hands, feet/ankles, and face.
It will kill me one day. I'm doing ok right now, but someday...
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Please check out www.patreon.com/learnelectronics and pledge a dollar if you can. It will go a long way to keeping the channel alive. It costs a bit of money to buy all the items and produce these videos. You help is appreciated.
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Here is all the gear I currently use:
Oscilloscope 1: Rigol 1054Z amzn.to/2PRybtN
Oscilloscope 2: Siglent SDS1202X-E amzn.to/31Kk1yH
Power Supply 1: TekPower TP3005N amzn.to/2TeQnxI
Power Supply 2: RUIDENG DP50V5A amzn.to/2sNicSe
Signal Generator: JS2800 ban.ggood.vip/d9vk
DMM1: Owon18B amzn.to/2SbIGLs
DMM2: Aneng 8008 amzn.to/2sNQncI
DMM3: Aneng 8009 amzn.to/2S5qeEp
DMM4: Uni-T UT801 amzn.to/2S89SuL
Soldering Station1: Zeny (Yihua)862D+ amzn.to/2S49z4e
Soldering Station2: KSGR T12 amzn.to/2Wk7Dn9
Light Meter Smart Sensor AS803 amzn.to/2B2gyRg

[@mikeoliver3254]

I’ve had cheap breadboards do this to me in the past. Spend forever looking for a fault only to touch something and the circuit comes alive, worst part is I’ll have touched the same connection before with zero results. Love the classic circuits videos Paul. I’m glad that you showed the circuit not working and then it suddenly started working because I watched very closely at the setup so I was confident you hooked it up right, it makes me feel a little better seeing that it’s not just me this happens too. Great video Paul, thanks for all you do for us.

[@wizardtwl]

hi Paul the circuit worked after you put pressure on the hi side of the 10K pot which may have seated the hi side better?

[@floretionguru2977]

I recommend breadboards from Sunfounder- no affiliation, just good experience with them.

[@simonlinser8286]

i hate it because ive built circuits before. im tempted to just start soldering directly to the leads but i don't want to set up a fume extractor. i guess people are right when they say just to buy it, but i don't want to buy it!

[@grzesiek1x]

it happened to me many times with RF circuits and then i started soledring everything (I mean when it is necessery) and my old designs start to be alive at the end...

[@mariofilippi3539]

You are a gifted teacher, thanks so much. Breadboards always confused me but after watching your video I've decided to dust mine off and give it a try using your LM386 setup.

[@isoguy.]

Those chinesium bread boards have been the bain of my electronic projects. I spent days trying to find a fault in one of my projects only to find that the positive and negative rails had three breaks along their lengths and the wire insert holes on the board only made loose contact with the inserted components. Hence, parts of the circuit would not function at different times during the fault finding process, Nearly drove me round the twist, thinking I had done something wrong. Self doubt started to creep into my thoughts. Saved up and purchased a good quality bread board from one of the quality electronics suppliers and now rarely get intermittent faults. Great vid and thanks for sharing this project and the fault finding approach which is really important when our projects don't work as planned. ⭐⭐⭐⭐⭐

[@lingcod91]

Actually the same problem for me. Now (especially today) I don't trust anything from China, which is sad. More counterfeit parts showing up. Locked down trying to do simple circuits with crap parts. And the hell with Amazon which seems to feature nothing but crap.

[@acestudioscouk-Ace-G0ACE]

Many producers would have edited the non working part. I'm glad you showed it as it's real life and it shows newbies that things don't always go right first time for experienced people.

[@learnelectronics]

Things rarely work 1st time for me.

[@acestudioscouk-Ace-G0ACE]

@@learnelectronics That means there is hope for me yet! Keep up the good work, I learn a lot here.

[@davidbranquinho4796]

Love your videos. Invaluable info. Thank you.

[@lonefeather4602]

Hey! I'm in geezer mode and have had open heart to repair a bad valve. Pacemaker, defibrillator, medication, some years later, still ticking. AND enjoying electronics. Been involved with the stuff for many years and finally have the free time to play with it and have been noticing your vids for some time now. I subscribed and plan to continue enjoying your videos. Yeah, sometimes the magic just happens. Good job, good work, good health.

[@cubesjdd]

I love all your videos.. Thank you for all your work.

[@heyitsandrew2209]

I love watching this videos while I'm tinkering along. Thanks dude!

[@MrManta2012]

Thanks for spending the time. the fact that you trouble shooted is really helpful to me. Thanks

[@jamesspring8862]

You know your trial and error really helps me. I'm a beginner at this but you make it relatable. Thank you

[@alzeNL]

the LM380 ! As a 15 year old in 1987 I used this in my GCSE Electronics project :D Passed the practical, was crap at the theory. Still love your lessons, and seeing a varient of the LM380 made me smile.

[@AlejandroStars]

Thank you, good engineering work, sometimes problem solving work is more valuable than the solution itself.

[@JohnClulow]

I picked up some LM386 to start learning about audio amplifiers and happened upon your video before they arrived. This'll be a big help. Thanks! Also, good to see I'm not the only one who runs into these little snags when experimenting where things should work but don't. Always an opportunity to learn from. I was wondering if you tried putting the blocking cap back in to see if it worked then (which it should since the speaker shouldn't be receiving DC)

[@norlin76]

24:33 when he switches on the supply you can actually hear a faint high pitch sound. The amplitude drops when his hand passes over the speaker so that should be the source.

[@kaoshavoc]

I love your vids man. Thanks for the awesome work.

[@_crazytechz]

Nice one like video Helpful sir Thanks

[@ibendiben]

I heard that too. And earlier an even higher pitched sound.

[@scottstevens7569]

Love it! A REAL learning thing there. Seems like a lot of my projects go that way ;), sometimes all it takes is a drop or taking out and putting back a few components, change a wire colour, go have lunch and VOLIA! She works! I am the GREATEST!! Stay safe and Don't Touch Your Face👍

[@rcstl8815]

Everyone knows the wire color is usually the problem.

[@LitesLAB]

Great vid Paul! This would be the other half of the Tremolo! Combine the 386 with the 741 oscillator circuit(need to add speed/depth controls) using a light-dimming resistor(LDR) and you’re almost there! Being a man of the strings, thought it might be of interest!

[@dennyoconnor8680]

Proof that for this kind of experimentation an oscilloscope will help you keep your sanity. A $15 old tube oscilloscope from a ham radio swap that still works and can reach 5 megacycles will instantly show what is oscillating and amplifying and what is not. I know this is an ancient thread but you do the viewers a disservice when you discourage them from getting a cheap scope.

[@webslinger2011]

School coursework had us use arduino and a 12~25V h-bridge motor driver. Output sound was fine but you can see the speaker cone move up (maybe about 3mm) when initially turned on. Already had an LC filter on the motor driver output going to the speaker.

[@bjl1000]

Love that static free box.

[@yodensherpa5678]

Your small talks with the parts always get me 😂

[@karlschulte9231]

Also a cap around 1 UF or so between 1 and ground helps remove dc offset and slightly improve non- flat topping ac swing. Yes, you found 8/5 thing. Nice video on using these test/ mockup boards too! Nice video. 73 Karl

[@_crazytechz]

Nice video helpful Thanks sir

[@sohelrana8376]

hey old man you are awesome and i learn more about your content ,,,,,,i wish keep alive long with good health

[@Perspectologist]

It is good to see alternatives to oscilloscopes, however there is also benefit for people without a scope to see the wave on yours. Before I had a scope I never felt alienated when I saw a scope used. I appreciated seeing a visualization that I couldn’t easily produce on my own.

[@_pilly]

8:09 “Who wants to come out and play?” 😆😆😆

[@mandelbro777]

Always a pleasure to watch your vids. Good explanations as always; only the things that need to be communicated, plus a little bit of clean american humour. Greetings from Australia.

[@simonkormendy849]

That little circle with an arrow in it is the symbol for a constant current source, it is part of the biasing system for the output transistors in the LM386 schematic, that's there to get rid of crossover distortion.

[@michaelpadovani9566]

Great troubleshooting video at the end and shows what you can do without a scope. My guess the source of the problem was any combination of loose breadboard wire, ineffective low pass filter, and too large of a dc blocking capacitor (?) ... sometimes you can ask why but never know the true solution!

[@AI_Image_Master]

Experience tells me that with the -4 version 5 volts is the very very bare minimum power supply and you really need more then that for it to work. YOu should be using 9v.

[@4DRC_]

JLT made a good discovery about terminating the inverting input w/ a capacitor instead of just shorting it to ground. Internally it keeps the other half of the diff amp stage better balanced, instead of just shorting the base of the inverting side input transistor. Overall a fickle chip but trusty once the kinks are worked out.

[@alfonsoincorvaia2595]

Great video. I have a LM386n that's acting funky. I built this circuit to see how funky the chip is acting and bingo. The chip is good for nothing. Thanks again! I enjoyed this video!!🙂

[@ron.owensby]

I love that you trim your leads, I cringe when I see breadboards that look like a plate of spaghetti. Thanks for you videos! PS I've given up on getting any Op Amp ckt to work. 👍👍

[@learnelectronics]

Don't give up

[@simeonmihaylov6123]

Hey Paul. Some more diy breadboard projects would be nice to see. Personally I find them very interesting. Thank you.

[@TheEmbeddedHobbyist]

You need the output cap as the lm386 output pin has a dc voltage of 1/2 the supply rail on it. Removing the cap will cause current to flow in the speaker all the time which would kill the output driver in the amp or blow the speaker.

[@hoofbags]

In English, we read from left to right and I find working with circuits similarly. Bread board makers ignore this so rails are horizontal. Especially apt with 386 as all inputs are on left side, outputs/supply on right: easier. I have problems with ground symbols instead of ground buss line. As LM386 has 40db gain, pin 2 ground needs to be first on left, 4 on second, zobel network grounded next and supply point last, on right, as done here. Doing it otherwise can causes motorboating, instability, I've found. Also, even the best solderless BBs can have an occasional unreliable tie point. Informative and stimulating upload: from learnelectronics. Thanks. 🙂

[@SarahRWilson]

Having worked with the LM386 in headphone amplifiers, I've found that they tend to stop working around 5V or so.

[@FranciscoVargas-cw9xw]

Did the 555 get hot without a cap couple on output to the lm386 input?

[@warplanner8852]

Paul, extremely sorry to hear about your condition. Please take care of yourself and stay with us for a long time, hear? Your hands are fine and your videos are excellent! As to the opening part of the video, know you this: I am terminal OCD and spend a great deal of time organizing my parts and components and **still** invest a lot of time looking! So, doing the math in my head, you're half a length ahead in the race! Persevere! ..oh, and does it work with the blocking cap back in?

[@larryshaver3568]

is there a stereo [dual amp]version of this chip? i would like to get one if there is

[@christheother9088]

Will that thing work with a dual source?

[@karlschulte9231]

It may be the pins sockets are not tight. I find coating leads with thin layer of solder adds a tiny bit of diameter and helps on very thin wire.

[@norlure]

I had a shot every time you said 555, thanks a lot I got to go for a nap now....lol

[@keithking1985]

WOW!! you must be reading my mind Paul.. I said on last video that im going to build a flashing light for my nephews school project!! was going to us the relaxation oscillator! but have no op-amps left to hand.. so im going to use the 555 with the triple low pass filtering to a nice slow sine wave.. what are the odds you put together the circuit in very next video... i would be even happy with the triangle wave so as not to lose voltage!!, just need a blinking light. i KNOW there easier ways to do it but wheres the fun in that....

[@ku4nz]

I know, you read the book when off cam :) Interesting as always. A request, have you done a video on list of common chips, such as 555, we should have and good source for them?

[@ianbertenshaw4350]

I like to think of the LM386 as the NE555 of the audio world - The little chip that could- well sort of !

[@larryshaver3568]

how many milliamps is the bench supply putting out?

[@alekrand85]

Couldnt get mine to work its still sitting on my breadboard.

[@melplishka5978]

Ty great vid lol

[@BrucesWorldofStuff]

Well Paul, I have to say that the intro is me looking for 2 hours to get the parts for a 10 min project. I feel your pain.. Lol Well that is what happens when you have to many negative electron going the wrong way and the positive rotation of the Moon is in the rising of the 3rd phase.... ):-D Glad to see the trouble shooting aspects of the projects even it they are a Head Scratcher to why it is what it is... LLAP

[@learnelectronics]

Thanks

[@rickloresto9647]

why it did not amplify....i heard the same sound when you connect the speaker to the 555 without lm386...

[@claytonbenignus4688]

I am a bit bewildered about inverting inputs. You used one 555 chip to create a tone and input to pin 3 of the 386. What happens when pin 2 gets some input? What if (and I am now using the Number Theory Definitions of Mathematics) the periodicity of both 555 inputs to the 386 are relatively prime?

[@larryshaver3568]

what is the maximum output of an lm386?

[@TheEngineer601]

The capacitor 250mf was the problem?

[@vivianastridge2167]

I have been searching for a design of a simple amplifier fed by an electret condenser mic feeding into low or usual impedance headphones. The mic would be placed on the inside of the edge of the bell of a saxophone taped on or otherwise held there. You mention that you had earlier given details of just this type amplifier. I would be very grateful if you could give me the link to the video where you have given details. If your video is no longer available could you be kind enough to give me constructional details etc etc of a suitable amplifier. I shall be eagerly looking forward to your link or other information. Thank you.

[@pulesjet]

The LM386 is one handy little rascal. Used butt loads of the things.

[@andyjohnson4485]

Was going to give you two thumbs up, but then I thought the innuendo would be too much, so I only gave you one!!

[@wendellhammond7853]

One serious question , where did you get your G .E F. G . W . Sgt. W.W Hammond

[@danielmaclean4718]

Literally the exact type of thing I was looking for, great as always.

[@TBL_stevennelson]

I have had the same thing happen to me. I hope you have success with out the odd behaviour

[@keithking1985]

there was a change in the sound when you 1st switched on.. can barely hear it tho...

[@simonkormendy849]

If I'm not mistaken, that pot appears to be working backwards, the way you have it connected up, the sound from the speaker should get louder as you turn the knob anti-clockwise.

[@GeorgeC1andonly]

Two thumbs up

[@teodoromedina9134]

i dont know ,but i dont see the tel connected yet

[@erikvincent5846]

The LM386 has 3 variants. The LM386N-1 and LM386N-3 run with a minimum of 4V. The LM386N-4, runs with a minimum of 5V. Which one were you using?

[@frankfalcone5951]

“Close enough for government work!” 😂

[@alexdickey9542]

I think the pot wasn't fully connected to the breadboard. After he tapped the pot down with the meter probes, I think he got a better connection.

[@ron.owensby]

I am thinking poor connection somewhere, also.

[@coldfinger459sub0]

Just like real class with all the problems. ELEC 101

[@SidxEden]

is your speaker 8 ohms?

[@gerryroberts662]

My disk cutter is more of a mystery i guess, at least thats what the local repaire guys i have been to, not real help, This video is a lot of help. Keep makeing them.. LM386. Have you used a larger audio chip for Mic and line in ??

[@miltonderezende7906]

I made an amp like this, exactly the same, and it turned out really bad. The oscilloscope showed a very distorted wave. I tried other IC's and it was always very bad.

[@babybear4862]

I thought pin 5 is out put.

[@drivejapan6293]

It is. He fixes it around 14:25

[@SteveRichfield]

I must have missed something here. In the IC diagram, you can see the NPN pull-up transistor in wired as a (presumably) 4ma constant current source, which according to Ohm's law will pull up an 8 ohm speaker only 32mv. Yet, they advertise reasonable fidelity. How are they doing this? What have I missed?

[@studiovlog3635]

y i have a lot of noise?? and loud distortion?

[@jaimecosta2966]

a recon the problem is with the bred board.. saying that i am going to add this Chanel to list of favorites .. wish you well

[@learnelectronics]

Thanks!

[@JerryEricsson]

Just a note, I lost my Brother-in-law last year to CHF. Not a pretty way to go, his scream echoed the hallway of the nursing home they sent him to so he had a place to die. My sister, his wife followed him two months later with heart failure, we all knew it was a broken heart, in the same nursing home room, where she went to recover from treatment for lung cancer. My eldest sister followed her two months later from brain cancer. Mom and I are the last of our family mom just celebrated her 94th birthday today, I will see my 69th in May. Ah 69, the memories that brings back..... Ah well we were all young once, were we not.

[@timwsac]

Hi, Paul, I gave you 3 thumbs up mate lol

[@ralphmills7322]

I had issues with breadboards from China. I've had to use a sewing needle to align the metal contacts with the correct holes in the plastic. Once aligned I use a double row pin header to insert, remove and re-insert. After that treatment they tend to stay aligned and are useable.

[@larryshaver3568]

i would change the 50nf capacitor to a 70 nf capacitor or slightly more

[@FEMADEATHCAMPCONTROL]

Loved the beginning. Thats like everytime isnt it. The thing in the diagram is a current source symbol not a diode.

[@jameskidd7906]

I think for this experience it's better using oscillo than fr meter it make what is wrong easy to find. anyway i think the problem is the bb .at the end thank u sir for the vid

[@geirendre]

"More time looking for parts than building..." ? That's when you know your storage system has room for improvements, LOL. And if you put it in the wrong hole, of course you'll struggle to get it working again.

[@squidkid2]

It started working when you removed the output capacitor. You should plug the output cap back in and see if stops working. Then I would try a 220uf cap because that's closer to the spec of 250uf that the schematic calls for. I assume that output cap is some kind of coupling cap. Perhaps the larger cap is attenuating the output to the speaker to the point where the volume is so low you just can't hear it. Also, I would try to figure out if your gerry-rigged sine wave input is at a high enough level to drive the input. You might check to see what level of input the spec sheet calls for. And you might just try driving the input with a signal generator outputting a sine wave of a known voltage.

[@MnHf-yh8il]

How I can use microphone in this circuit???

[@rcstl8815]

The two places he has the 555 output attached. One speaker lead to ground, the other to the pot, the white wire in the video..

[@MrIneedalifenow]

Just wondering, I was taught that when you use a breadboard, you should have the positive up and the negative down. Is there a reason you do it blue, red, blue red or just by habit?

[@ron.owensby]

That's the way all of my breadboards (That have two power strips, top and bottom) are. Besides if you rotate his BB 180 deg. it would be red, blue, red blue. Furthermore, he is using the red/positive strip on top and blue/negative on bottom.

[@williammentink]

It's actually marked on his bread board. There polarity that is.

[@sdrtech]

Maybe it was trying to amplify a square wave and the capictor was blocking dc bias

[@melplishka5978]

Hahahahahaha I got the glasses with the microscopes on the lenses. My wife laughs at me when I use them on the bread board lol.

[@GiNodrog]

The secret of the LM386 and many forget, you must include a supply decoupling capacitor . 10uf or moor. And it's often excluded in the data sheet.

[@GiNodrog]

The centers connections on sk10 power line patch board are usually open cct.

[@rrowan327]

First, Yeah Right - Golf..... Maybe the powering on and off of the supply woke up the LM386 chip. Since we know the power supplies do an overshoot on startup.

[@manofmesopotamia7602]

9:49 😳Pin 8 with 1 are the gain pins, pin 5 is the output

[@adamhubert3472]

so far your videos are the best explanation and demonstration I've found. everyone else misses steps and assumes we all know WTF they're talking about. thanks for being thorough.

[@JerryEricsson]

I would guess that you had a bad contact on the pot, by putting the meter on the pot, you pushed her down enough to get contact once more and IT LIVES!

[@learnelectronics]

That's what it seems like

[@davidluther3408]

@@learnelectronics YOU MIGHT TRY SOME CONTACT CLEANER TO SEE IT HELPS.

[@captainpugwash4100]

Sometimes it works and sometimes it doesn’t, for no fathomable reason, sounds very much like “government work” to me! 😷 Happy Corona Day!

[@teodoromedina9134]

if you want to hear the sound you have to connect the audio from the source

[@carldavis8228]

Of course

[@Timsturbs]

blocking cap on input needed

[@Timsturbs]

also it performs better with a cap from -in to ground

[@alchemy1]

Thanks for reminding me. I need to get some of them baggies. What happened here happens to me all the time. Except I quitely get mad and keep it to my sorry ass self.

[@mr.bianchirider8126]

So I’m not the only one this happens to.

[@MrVosh-nj2lc]

Demo of the "pires"to be!

[@awesomekiertechtips3838]

It doesn’t work. The pot is connected reversed. The signal goes directly to ground. When you turn the pot clockwise it shouldn’t output sound. Maybe the chip is bad. Or decoupling cap before the potentiometer

[@NotMarkKnopfler]

Looking at the diagram, pin **5** is the output, not pin 8.

[@learnelectronics]

As I said in the video....maybe watch the whole thing before commenting

[@larryshaver3568]

yes .05mfd is 50 nfd

[@attilarivera]

9:55 Ur mistaken. Pin 8 + 1 is for gain. Pin 5 is for output. 😆