Introduction: 20 Watt Stereo Amplifier-simple and Very Cheap

Picture of 20 Watt Stereo Amplifier-simple and Very Cheap

want to listen to your favourite music loudly,but dont have any powerfull amplifier??want to have self made music system???are you getting bored of nasty and useless mono sound from tv,music player,dvd??want to have a self made cool and rich sound stereo amplifier but dont wanna spend alot???then your on the right place!!!!

this is one stop solution for all your problems related to stereo amps!!!!

guys this is my first instructable and i am quite new to instructables website,so dont be harsh toward my instructable.

today im gonna tell how to build high quality,simple,and cost effective amplifier.

this amplifier gives 20 watt output sound(really very loud!!!!)

# sailent features of the amplifier

* this amplifier is of 2 channel-stereo is based on IC TDA 2009 chip.

* this project cost for me was only 96rupees (under 2$ USD).

* very easy to build

* requires only basic electronic knowledge.

* very few components.


please watch the video embeded in the last step to know the quality of the amplifier..

guys i have build this amp referring to the electric circuit website

please refer this website for additional information.

credits for circuit and pcb layout goes to electriccircuit website.

Step 1: Components Required

Picture of Components Required

this circuit requires very less components.

main component of the circuit is IC TDA 2009A.please refer the datasheet for additional information on the ic


1) ic tda2009a

2) CAPACITORS 2.2uf/25v X 2 pieces; 470uf/25v X 2 pieces; 22uf/25v; 0.1uf disc type X 3 pieces; 2200uf/25v X 2 pieces; 100uf/25v

3)RESISTORS- 1.2k X 2 ; 18 ohm X 2; 1ohm X 2

4) a audio connector wire of earphones 3.5mm

5) copper board for etching.

7) soldier gun and some logic

NOTE-the 470uf capacitor in the schematics is equall to the 220uf cap in the pcb layout,you can use either of them.

Step 2: Hardest But Simple Step!!! ;)

Picture of Hardest But Simple Step!!! ;)

we have to assemble the circuit as shown in the circuit diagram.

i have used a 6cm X 4 cm copper board.

just etch the circuit given on the board and drill the holes where the component have to be assembled.

Step 3: Assembly

Picture of Assembly

we have to assemble the components into their places in the pcb.

now solder all the components in their places..DO NOT DRY SOLDER THE COMPONENTS .THEY WILL BE BURNT!!

attach the heat sink to IC before soldering it.this will prevent the ic from getting hot.

for heat sink i have used a L shaped piece of aluminium..

NOTE- the IC generates a lot of heat which has to be my heat sink is not enough large to dissipate the all heat generated...use the heat sink as large as possible.

Step 4: Supply, Input and Output

for input,i have used the old 3.5mm earphone audio input jack wire.

for output speakers- they should be atleast 15 watt rated speakers.

for output connection-to connect and disconnect the speaker i have used male/female AV connectors.

supply used here is of 15 volt 1.3A bench power supply.

if you dont have a proper can make it at home using ic 7815 it for more information.also see the pdf file attached..

Step 5: DONE!!!!

hurray!!! we have just made a nice and simple cost effective amplifier!!!!

the ic and heat sink can become very hot so do not touch them while operating.


i have uploaded the video of this amplifier in work!!

thanx guys for reading my instructable and please VOTE for my instructable if you like it.


steve.criss (author)2015-04-24

R5 and R6 are different values on the schematic. This is certainly a typo. How did you decide to go with 1 Ohm resistors instead of 10 Ohm resistors?

thanx pal for reading my instructable.

i decided to use 1 ohm instead of 10 ohm because i thought less the resistance,more the power is delivered and more sound is reproduced!!!! its just a guess,i have used 1 ohm in my project...i just dont know what is the effect of the 10 ohm resistor...

Looking at the TDA2009a datasheet that you provided, the test and application circuit shows 1 Ohm resistors for R5 and R6, so your guess seems to be correct. From my limited knowledge of amplifiers, it looks like the C6/R5 and C7/R6 circuits provide high frequency stability where loudspeaker inductive reactance load can become excessive.

haohmaru (author)2017-05-08

Hi Tiwari,
I used a 10k dual gang POT to adjust volume for 2 channels and this circuit working properly :D. now, I want to increase bass for this circuit but I dont know how to change this circuit. Could you please suggest the solution? thanks.

Delandro (author)2016-07-09

Are there any other chips that i can use instead of ic tda 2009a ?

PawanS32 (author)2016-05-22

Dear prabhat i don't understand to your ckt diagram....can you please simplify it with ic pin numbers

Prabhat Tiwari (author)PawanS322016-05-22

Its already there in circuit block diagram

aoakif (author)2016-03-21

i just make one but how do i lower the gain when i connect it to my pc or mobile with a high volume its sounds creepy. and one speaker is sounding like tweeter with no bass and second one have a nice bass with a 6 ohm 20 watt speaker and is that normal or i have done something wrong ?

Prabhat Tiwari (author)aoakif2016-03-21

Can you give me the specs and images of speaker?...have you used a proper and large heat sink??.it might be something wrong with one of your speaker,just interchange both and see if it happens on good speaker also....and to control volume,add 10k log potentiometer before each speaker output

aoakif (author)Prabhat Tiwari2016-03-22

this is the circuit i used and i have used a big heat sink and the ic doesn't goes hot but the problem is creepy sound like it is having a high gain i also used a 10k stereo pot but it dont sound good

Prabhat Tiwari (author)aoakif2016-03-22

Slightly increase the R2,R4 resistance to reduce the gain..for more detailed information kindly refer the datasheet provided in above instructable

aoakif made it! (author)Prabhat Tiwari2016-03-22

i have done it with 33ohm resister it just make i little difference about 10%.

and if u see the second diagram it says that u want to have a 200mv input so can u tell me how to measure my pc output audio signal with multimeter

Prabhat Tiwari (author)aoakif2016-03-22

use the multimeter on ac voltage mode.i think gain is not your problem,your problem might be inadequate power supply/faulty speaker/faulty input cable..did u checked it??

aoakif (author)Prabhat Tiwari2016-03-23

thanks for the help and replying me with your help i just make it sound good thanks :)

Prabhat Tiwari (author)aoakif2016-03-30

always welcome and dont forget to like my instructable and vote up for me.cheers!!!!

aoakif (author)Prabhat Tiwari2016-03-23

1)my output from pc was about 6mV and the amp input was 2mV the difference is about 33% more input.

2)i was having good sound at about 20% volume from my pc so 33%-20%=13% so the gain i wanted in my amp with 6mV should by around 13%.

3)then i calculated gain of my amp (1+R1/R2) 1+1300/18 = 74% gain.

4)i use a 150ohm resistor. with that(1+R1/R2) 1+1300/150 = 10% gain.

so when i take out the difference in both gain in % (10*100/74 = 13.5%) and its about ok the ic is now working as i wanted with clear and good sound.

and it generally gets slightly distorted on high input.

aoakif (author)Prabhat Tiwari2016-03-22

this is the speaker i am using now and i use this this circuit directly to the pc output i think i should use some kind of filters but i really dont know how to do that

Abhi909 (author)2016-01-31

great project

can i place your project on my website.

i'm working on a website which is related to electrical projects.

i also mention your name.

plz reply

Prabhat Tiwari (author)Abhi9092016-02-01

Yes ofcourse.and i will be appriciated if you mention my name and link of this instructable on your website.also please send me your website's address to me @

chrisjlionel (author)2015-10-18

how to control volume?

Just add the 2x 10k log pot before speakers

Thanks for the quick reply

Tu An (author)2015-09-05

Hi, I am a newbie in making diy projects and have very limited knowledge about electronics. So, I just want to ask if you bought the pre-printed PCB or if you etched the board to make the circuit?

Also, is it advisable use the perf board regarding the high level of heat produced?

Prabhat Tiwari (author)Tu An2015-10-14

Use pcb instead of perfboard

Prabhat Tiwari (author)Tu An2015-10-14

I etched the board to make the circuit

StormH1 (author)2015-08-03

What resistor would you replace with a potentiometer if you wamted to be able to control the volume ?

Prabhat Tiwari (author)StormH12015-08-11

just add a 1k pot to the input of the will need 2 of those for stereo

akki5230 (author)2015-05-24

Hi, I have made this circuit recently but, it's not amplifying the sound, but lowering it. What could I have done wrong?

akki5230 (author)akki52302015-05-24

It's working but just for a fraction of seconds it gives amplified sound just when I power it, and then very very low sound, almost nothing.

pktiwari (author)akki52302015-07-12

I think you have a loose connection to the amplifier chip legs

roggerdae (author)2015-06-15

im gonna try ur idea out

pktiwari (author)roggerdae2015-07-12

Yaa sure you will be pleased by sweet sound

gaestes3 (author)2015-04-23

thnx tilehead (sp) - simply awesome instructable. good data, etc. maybe the u.s. - online '' has chip(s) & tech assist. it would cost me quite much more to get the items here the middle of nowhere philippines - no matter...someday. repeat: well done amigo, very nice > my 50A louds.

gaieb (author)gaestes32015-05-25

I have the same problem, have to wait till I make a trip to Manila to get parts.

Prabhat Tiwari (author)gaestes32015-04-23

Thanks dude for reading my instructable

gaestes3 (author)Prabhat Tiwari2015-04-24

thanks amigo; i daubbled a little with the circuitry stuff > stereo is...well the webster's definition flat sucks > the 3 dimensional effect of reproduced why i threw up the speaker pics > kinda difficult for the typical computer geek (or anybody for that matter..) to 'market' wi-fi wavelength pc sound systems while blistering their inner eardrums listening to a laser driven, $.20, less than zero mono box. consideration of the loud family >

thanks prabhat

toby7 (author)2015-05-11

R6 Should be 1 Ohm as well, not 10 ohm in the schematic and parts list.

Prabhat Tiwari (author)2015-05-04

Thanks for providing the parts list for readers

vardaan1234 (author)2015-04-29

it is a good project but i am not abke ti see that wgere you have solder the input cable

You must solder it to the IN.R,IN.L and GND

Eddie_T (author)2015-04-27

For diy speaker enclosures see this thread for great sound performance frome foam core cut with xacto knife:

Graham Leach (author)2015-04-23

Very cute amp.

Personally, I love this stuff, and have for years.

Hopefully, gentle reader, you will too...

Here's the data sheet for this IC, for those who want to dig a bit deeper:

If you enjoy this kind of stuff, you might want to look into the world of gainclone, it's a very interesting ecosystem of DIY digital amplification:

Once you've tripped that light fantastic, the only other place to go is into vacuum tubes, which has its own unique rewards:

Thanks for sharing ur experience .have you made this amp earlier??

Nope. But all of these "one chip" amps are very similar-looking once you've done a couple. Your next challenge is going to be to make a nice looking enclosure. The gainclone people tend to make "improbable" enclosures out of whatever is lying around, like Altoid tins:

Now, your project is a little different because (1) its a 20W amplifier (2) It is an AB amplifier, which means that it can produce a LOT of heat when driving at 100%. My Class A dual monoblocks kick out enough energy to heat my house in winter when they get going!

Anyway, you might want to think about a HEFTY heat sink for this little toy, like a custom crafted aluminum one, which we sometimes use for laser heat sinks (they produce a lot of heat too):

NOTE: If the tab on your amplifier chip is not isolated, it means that it carries a potential (a different kind of "HOT"), which can SHOCK someone in the wrong circumstances. I have not checked, but you should.

Another very interesting material for heat sinking is concrete, which can be manipulated to make some very interesting and beautiful forms, though the heat absorption capability of concrete is much, much slower than metal or water:

Mind you, a water-cooled amplifier would be very neat, but not very portable. However, with an arduino-driven color organ, you could make a pretty light show to go along with your music:


ac-dc (author)Graham Leach2015-04-23

Hefty heatsink is not needed, though slightly larger may not hurt. He is using a mere 15V PSU which means this isn't really a 20W amp, only a 20W amp chip which driving 8 ohm speakers would result in only ~ 2.7W/channel.

What this instructable ignored is that on a chipamp like this, choosing the right power supply means everything. On the other hand, it's not necessarily wrong to use a 10W/ch. chip for a lesser output power. The cost difference can be pennies in some cases and having a more robust chip can ease the heatsink interface, even provide better performance at any wattage and more protection features.

Regardless, instead of this project being called a 20W amp it should be called a 2.7W/ch. amp.

Prabhat Tiwari (author)ac-dc2015-04-25

it can also make a burn mark on your hands within a second if you mis handle it .it really produces a lot of heat even when the aluminium heat sink is attached(shown in the above images)

i usually use the pc fan to cool this piece of metal.

Prabhat Tiwari (author)ac-dc2015-04-25

hey ac-dc thanks for reading my instructable and helping my readers solving their problems..but as mentioned in the project,the amp is driven by the 15 volt 1.5A power supply which is more than enough to drive a 20 watt amp.and i think the amp is really the 10 watt per channel amp because i have a 3watt/channel ready made stereo amp which is nowhere in the comparism with this amps.and i personnaly think that the circuit provided by the electriccircuit is might want to check their website in the below link

Thanx for info...but I didn't get any shock until now( using since a month)

Prabhat Tiwari (author)2015-04-25

thanks for your information!!!i appreciate that :) .

actually that idea did struck my mind to add a volume control and use the audio jack and three twisted wires for the input..for that i have to buy them,it would increase the total cost of the amplifier.however if some one wants to make it more comfortable and easy to use,then they can add some more stuff like these

About This Instructable



Bio: i'm a college going guy who lives in india.i like to make electric gadgets and play with them.with the little knowledge of ... More »
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