I'm self taught. I finished high school and no more. :) I learn by studying, reading, doing. :)

Cheers for the video mate, you've literally explained in 7 minutes what 5 months of browsing a forum couldn't teach me.

i just built one with 2SC5200 NPN and 2SA5200 PNP transistors, the amplifier it's powerful I almost cracked my ear diaphragm as I was too close to the speaker, thank you ! I also noticed an overheating of the transistors

I want to thank you for your tutorials; they have saved my career! Thank you so much!

Truly amazing!! I made this for my college project and its working perfectly fine... Thank you so much Sir!!

@anceop The negative output is derived from two sources. The NPN for the positive wave cycles, and the PNP for the negative wave cycles. Since the sum of these two is an ac voltage, a decoupling cap is needed AND it's on the negative side of the circuit therefore it's negative lead goes to ground, and the positive to the load.

This is our school project and what a co incidence that i were supposed to design with the same values as you did..thanks sir it's so helpfull for me

You might consider 1Ω resistors between the emitters and the output on each of the output transistors. That way, if the output transistors get hotter than the 1N4148 diodes, the bias current doesn't increase, which could lead to thermal runaway. I like the way you used the speaker and the output capacitors to serve as the bootstrap, rather than adding another resistor and capacitor to serve that purpose. Fewer components, and, more importantly, LESS DISTORTION! I never though about that. I don't see a problem with the 9 milliamp DC bias on the speaker coil, since the I^2R loss is negligible. The only possible caveat is that the output stage MUST be loaded with a low impedance load. This output stage cannot be plugged directly into an auxiliary input of another amplifier, without a low impedance shunt, because it won't pull up the high side transistor on the output stage, through the 1KΩ resistor. On the input, it might be worth while to include an emitter follower and voltage divider, to help the input transistor hold the output more accurately between the supply rails. That way, it would be less susceptible to supply voltage variations, and possibly increase your input impedance. Less distortion yet, but at the expense of some gain.

I want to build an audio amp in 2021 and the best videos are at least 9 years old 😂 thank you for that Tutorial!

Those PPI amps are great! I used to install them. I have repaired them and what usualy goes bad are the power transistors.

What's the use of the third transistor Q3?

Witty, educational and it has good music, as usual. Great stuff!

Very nice...people needs that...i will put your link in the diy audio forum ....people do not say..but they need this kind os stuff you're doing...teaching the very basic things for them..... great that..... congratulations!

newbie question here: what component is he using to connect the audio cable to the circuit?

aaaand you've got a new subscriber, loved the presentation

Could you please tell us how you selected the biasing for these transistors? what sort of DC bias you wanted and why? Also, what is the reason for choosing a "47u"F coupling cap at the input ? (and 10 times that at the op) Thanks.

@casvanmarcel The opening track is by "Obits" and it's called "Talking To The Dog".

Do you have any calculations of this circuit, like the gain, bandwith,...? Thank you!

Great vids! Where you insert at pot into this circuit for volume control?

I remember playing around with a circuit like that in my father's basement, the only difference here is that R1 seems to provide both bias and maybe some AC negative feedback. So far, so good, but I found that if I left it running at more than a trivial power level, both transistors would heat up, run away and burn out. I think a resistor between the emitters, with a bypass cap at each end to avoid lowering the AC gain, put a stop to that.

Sure, I might be able to help. What are the emitter, base, and collector voltages around all three transistors with respect to the negative terminal of the battery?

Shoudn't there be a short protection on Q1/Q2?

It is a nice and simple design. I did some minor modifications to get it more under control. So I suggest to separate the boot strapping from the output to allow operation of the speaker against ground. I used a bootstrap network of 2 resistors of 270 Ohm and an electrolytic of 220 µF Then I put a 10 kOhm resistor between C2 and the base of Q3 to limit the voltage gain by some feedback. I increased R2 to 150 kOhm to meet the midpoint between ground and operating voltage.

Helped a lot, thank you!!

@blueblast88 The next time I do a project with those jacks I'll explain a bit more about them.

I need a hifi audio amplifier circuit with TDA 2030A. And please explain benefit about 12-0-12 and only 12 v supply. Which is the best choice

is there any particular reason you used a 2N3053 / 2N2905A combo instead of the more ubiquitous and much cheaper 2N2222 / 2N2907 duo?

hey, im reletivley new to schematics but i understood most of this exept for one thing. so at the top of your diagram you have a "+9 V" does that show the positive side of the power source? if so where do you connect the negative side of the power source? thanks.

Hi I'm Andrei and I want to ask you if you can make the Tda8944j amplifier to do it please

I made a Class B amplifier that's distortion free, I used an op-amp to drive the output transistors, and connected the feedback resistors to where the transistors emitters are connected so it gives a "corrected" waveform to the transistors to compensate for the cross-over distortion. It works quite well, is very efficient, does not go into thermal runaway and I use to power the speakers at my computer

hi. i have a DENON AVR-391 3D audio reciever for my 5.1 audio system and my centre channel is very very very low and i want to amplify just my centre channel. what amplifier setup do i use?

you sir deserver at least Thumb Up, if not Subscribe, great job explaining, thank you very much

Thanks, simple circuit and works great as a guitar headphone amp!

hi, I´m making this amplifier for a school project, the problem is that my teacher request 3 stages and this only have 2... can you suggest me how can I make this amplifier with 3 stages? thank you

When i built this my pnp transistor would get very hot. I checked my wiring and found out i put the wire going to the emitter on the wrong side of the 470uf cap. However the circuit does not work when i put them on the correct side, but gets very hot and burns out if i put it on the side that works...Any advise?

Ok. I'm confused. Do your transistors have an odd pinout. It appears your transitors are CBE (left to right) pinout? At 4:45 I can see you have what should be the E of the pre-amp NPN tied to the B of the 3906 (via red jumper) but that's not in your schematic?

It is too late for me to come across your video, is it posible to use 8050-8550 transistors on this schematic?

hello I want to make an audio amplifier / booster employing a transistor long-tail pair input stage (BJT or MOS) and a 250 mW BJT class-AB complementary output stage to drive a 25 Ω earphone speaker using discreet transistors. Ensure maximum output compliance using a max +6 V supply rail and a minimum total voltage gain of 20. The amplifier is to be driven by a mobile phone so input impedance must > 32 Ω to avoid damaging its audio output port. can it be done with this circuit?

How can we design a 10 watts audio amplifier using this method ?

Can I use op amp 741 with this circuit

very nice tutorial. what is the reason of using 47uF capacitor in reverse polarity?

great job i made on a year ago works great even at 3volts

Hello sir can I use this circuit to boost input signal. For amplifire.

Hey man plz can i use bc144 and bc143 for power transistor and bc 546 for preamp? i have to build it for tomorrow, thx in advance

Great tutorial! Here are my questions if you have the time for it: How powerful would this amplifier be in RMS? And what components would have to be changed to make it more or less powerful. And lastly, I'm wondering how you figure out how much power you need on the input(5,9,12v?)

Sir, can you teach us how did you compute for the value of r1 and r2. I would like to build this project on a different voltage. Specifically i want to build it with a 5 volt source. I couldnt figure out for the value of R1 and T2. Please help. Tnx i love your video

The baby at the back of the board made me jump

Hi, thanks for the video! What if I increase the voltage up to 24 volts, or even 30 volts? Do resistors wattage matter much in case of voltage increase? I build the circuit and hooked my guitar pedalboard (from preamp output) into it driving a 1x12 guitar cab. It sounded amazing, I wonder if I could build a tiny portable poweramp for my rig with little more juice and headroom. As far as I can see in the datasheet these transistors can handle up to 40 volts.

Sir can i use an 8ohm speaker for this circuit?

1N4148 this diode Schottky tiep?

My grandma doesn't want to pay $3000 for a new pair of hearing aids so I'm using this a pair of those jelly ear buds this project and a clip on microphone, thank you so much!

I LOVE THIS

hey Dean, would you make more electronics videos please, something with an amp or just transistors. thanks mike

Love this circuit. I made a few changes though. I changed the 1K resistor to a 470 ohm resistor, changed the 100K resistor to a 180K resistor, and added a 4.7K resistor before the input capacitor

You're Amazing! Thanks very much.

@nyuszifuben23 It's by "Garmisch" and it's called "U Fine". You can find it on free music archive dot org.

Can i use your pre amp with this amp

glad to hear the quintessential chip music on the tech vid.

Are you sure, that the scematic is correct? Especially the position of the two diodes?

how many watts is the speaker

Awesome project, thanks! Just finished building one. Two questions: if I wanted to use this to amplify a guitar signal (very low power), is there an easy way to up the gain a bit? Second, would you mind if I posted a video of my assembly? Giving credit to you for design of course.

what is the R2 for? is it some sort of feedback, or bootstrapping?

How many watts is that amp?

Can it be supplied12v

Can I use diode 1n4007

hi can you email me link to to the tutorials on all the class of amp

Do the diodes have to be in there, isn't that just to prevent you from switching + and -

if i buiold two for stereo can i power them from the same supply?

Can I use bipolar caps?

What is the music at the very start?

THANKS FOR THE VIDEOS

What's the music at 1:00? thx

it works fine with 5 volt. I used 5 volt regulator. and added volume control and low pass filter. my amplifier do amazing bass.

nice video man.. but could you explain.. what input source impedance.. and what output inpedance is... like is it a 8 ohm input and 8 ohm output... how how you can change the parts to achieve other impedances.. thanks man

Another good hack! Where can I get the cool radioactive tshirt?

what is the color code for the resistor?

Can someone please tell me where negative side of 9V goes? I am new to electronics but working on similar project

I've made this exactly according to the drawing, but i only get a buzzing sound from the amp :( i have 2SC3858 as the NPN's, and a 2SA1494 as the PNP, and 18 Volt DC

Nice but what if you don't already have PC speakers and you want to make them with little 8 ohms/0.5W speakers and get the signal from RCA outputs of a CD player for example ? PC speakers you show here already amplify the signal, doesn't it ?

You look like Dr.House, and as cool as Dr. House ! Thanks for the tutorial. How is it possible to improve the amplifier by adding common emitter stage or other stages? I am trying to understand how these different stages work? input, middle and output stage. thanks again.

That is you. You are the short protection for q1 and q2.

@HackaweekTV Thank you Dino

That's a "guessed" operating point. It is better to have a small emitter resistor for Q3 and use a third diode in series to enable to presetting of the bias point more precisely. The gain of the circuit is also more predictable, with a better cross-over distortion figure.

how to put the potentiometer? please i need your immediate reply.

How many Giga-Watts ??

thanks !

hey man, can you teach how to make a portable amplifier. I like your tutorials! regards!

Thanks for watching. More electronics coming up soon.

could u send me a jpeg of the schmatic

Why is the speaker connected to Vcc not GND !?!

Can I use a 8 ohm speaker rather than 25 ohms? I made the circuit but the sound is not clear. I replaced the 2n3053 with 2n3725. Is that okay? Answer please. Thanks.

Hi this is very good what is difference between video amplifier and audio amplifier in equal circuit.thanks

omg i used this circuit to make a power amp and it work!!!

thanks! xx

why not move the end of the diode chain to the collector of the bottom transistor has to be the same as the top transistor which should give a better signal as it will become Class A also needs a 10R resistor between the emitter of the top transistor to the collector of the bottom NPN transistor, the feedback comes from the top emitter to the base of the drive transistor via 560K resistor. I saw this version in the service manual for the TECHNICS SUA900 MK II.

Put a five volt regulator on the nine volt battery and connect the 5V out to your small amp. Easy peasy. LM7805 or LM340-5 should work for you.

WOW it 9 years ago

WHAT IS WITH THE K1 25 OHM AT THE TOP RIGHT OF THE SCHEMATIC. THAT IS AN ODD VALUE FOR A SPEAKER. I WOULD HOPE THAT THIS AMP WOULD WORK JUST FINE WITH AN 8 OHM SPEAKER. I LOVE YOUR VIDEOS YOU ARE A GREAT TEACHER. AFTER MAKING THE CLASS A AMPLIFIER THAT WORKED SO WELL I WAS SO DELIGHTED AT HOW WELL IT WORKED I BUILD THEM OFTEN NOW. IT WAS SO EASY.THANK YOU!.

What is the voltage of your capacitors?

Yes