10W R.M.S. Audio Amplifier




                             The aim of the project was to make an audio amplifier that can deliver up to 10W R.M.S. power output. input can be given via computer/mp3 player or a mic (mic circuit explanation at the end). there are many different types of amplifiers tda2003 is probably a class b amplifier because its power consumption is quiet low then normal amplifiers and also that its noise is very low.
the purpose for which i chose this ic is that it has very less external components, very low distortion,very low input power and a corresponding high output power.

                          TDA2003 is a 10W car radio audio amplifier The device provides a high output current capability (up to 3.5A) very low harmonic and cross-over distortion. Completely safe operation is guaranteed due to protection against DC and AC short circuit between all pins and ground,thermal over-range,load dump voltage surge up to 40V

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Step 1: Things Required

lists of components required to build the circuit


  • R1:220 Ω
  • R2: 2.2Ω
  • R3: 1Ω 1 watt
  • Rx: 39Ω                                  See the datasheet paw to alter the value of Rx
  • RV1: 10kΩ


  • C1: 2.2µF 25V electrolytic
  • C2:470µF 35V electrolytic
  • C3:0.1µF polyester or ceramic
  • C4:1000µF/35 V electrolytic
  • C5: 100nF polyester or ceramic
  • C6: 100µF 35v electrolytic
  • Cx 39nF                                       See the datasheet paw to alter the value of Cx


  • IC1: TDA2003
         :  connectors (cream shell connectors )
3-  2 pin connectors

Step 2: Helpful Material

Here is some helping material :
1- the data sheet of tda2003
2- the schematics of amplifier
3- and the PCB layout of amplifier

these circuits are modified ones the one i fabricated was a bit different .the difference was in placing the components not any thing else. if someone wants . datasheet open with any .PDF reader while the schematics and layout can be opened by Proteus (software) 7.0 or above.

Step 3: Circuit Diagrams

lets get started with the circuit the input form a computer or any other audio device will be given at the connector named as "input". u can even directly solder them if u want but connectors are easy to handle as they can be disconnected and reconnected without soldering and De-soldering except for the first time.

then the signal passes to the potentiometer named as RV1 it is just to control the input voltage and can be used as a volume control. c1 is a coupling capacitor and is used to block the dc portion present in the input signal.

c2 is present to reduce the distortion in the output as it is acting like a bypass capacitor (but u can see that there is 1ohm resistor except the ground so it is not actually the bypass cap.

c3 is there to reduce the ripple in the power supply and no other purpose similarly c6.

c4 is an output coupling capacitor . (i don't know the reason why it is there because it is reducing the BASS of the circuit never tried to reduce it if someone tries do tell me what happened).

we all know that there is a magnet and a coil in a speaker therefore they are inductive and inductors do not allow ac to pass through them that effectively so it is there to reduce the inductive effect of the speaker.

cx is present to reduce the higher frequency at the output terminal and also provide a feedback path to the amplifier.

                                    Connect a power supply 8-18V i recommend that u connect 16 V at least to get nice sound even when the volume is at its max u can purchase a power supply from the market OR u can use this link to make one for yourself
just replace the R2 and R22 resistors to 3k each to get +-16V (it was supplying +-12V)

at the output u can connect 2ohm/4ohm/8ohm Load to get 10W/8W/6W power respectively

Step 4: Demonstration Video & Modifications

here is a demonstration video :
don"t rely on this because the normal microphone of the mobile can not receive the bass so it seems that it has no bass but actually its base is awesome and also the video has distortion but actually the distortion is very low (zero below 50% volume) and negligible at 80% because the power supply is 12V if it was 16 or 18V then the distortion would be even less at high volumes .

another video

in case if someone wants to modify the circuit i.e.
increase/decrease bandwidth
increase BASS/treble
reduce noise
increase/decrease gain
the diagram shows how will the change in components affect these values

if u have any problem u can comment or mail me at dinitrogenoxide@ymail.com
and rate it if u like it :)

Step 5: Mic Attachment (Optional)

Here is a modification if u want to amplify your sound that u speak connect a microphone
u will need
a microphone
a battery
a capacitor 1uF (try to use a non polarized capacitor)
a resistor 2.1k

and a connector to connect it to the input or u may simply solder it to the input of the amplifier
NOTE make sure that u connect the ground of the amplifier to the ground of the mic (to ensure common ground) otherwise it may not work properly

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107 Discussions


Question 1 year ago on Step 3

Hi, many thanks for the explanation. I have a question: In the schematic of step 3, C1 is oriented (+) to input, but in datasheet is (-) to input. How would be the correct oeientation? Thanks in advance.

2 answers

Answer 1 year ago

Either way will work. IIRC having it reversed protects the input from DC in the circuit, should something go wrong.


1 year ago

Guys, I just made one (urgently needed audio for the webconferencing on my home PC)

But it is having too much gain!! Could you advise how this could be lowered? (I can limit input signal, but it seems amplifier having too much amplification)

I am basically SEEING noises!!)))

1 reply

Reply 1 year ago

Decreasing the value of R1 will decrease the gain of the amplifier. However It gets really hot already so Use one with a high wattage rating. as far as the noises are concerned make sure that the input device and the amplifier share a common ground. The POT can also lower the gain if you are able to fix the noise issue.


2 years ago

Hello.this is not related to this instructable.
I made a psu with lm317 using the common sschematic.i used your coarse fine adj method as well.resistor values are 1k and 10k pot with 1k pot for fine adj.
However the voltage cannot be adjusted using both pots.its always 10.6v with 12v vin.
I replaced 220R resistor to 10k and 1k pot and that reduced the voltage.then used 5k pot instead of 10k and 1k pots.its worked but max voltage was 8.5v.so i removed 1k resistor(R2) and placed 470R resistor now againg its not adjustable.
What should i do now.i cant imagine the problem.
Any suggestions?
And im not using fine tuning now.only 5k pot as R1 and 470R resistor as R2.

2 replies

Reply 2 years ago

Kindly see this image, it is from the datasheet of LM317. It has a formula that can be used to calculate the ouput voltage for a given input voltage. Remember if your input is 12V you can never get 12V at the output (due to power losses) therefore in any PSU the input is higher than the required adjustable output.
I haven't seen your schematics so I cant tell what is R1 and R2 but see this circuit for reference.


Reply 2 years ago

Yes i know but i think the ic is now i bougt new ill make it again in a breadboard.
Thanks for quick reply. ?


Reply 2 years ago

I cant find the exact values at the moment but the voltage should never exceed the supplied voltage, the peak value of supplied voltage is 36V so use 50V for each of the capacitors.


2 years ago


I want to make it dual channel Amp what can I do .... I am thinking to make two different circuits for the same ...is it right or what should I do , I am little concerned about power supply how could i power them i have a variable Ac Dc converter

1 reply

Reply 2 years ago

Yes, dual channel Amp can be made by making 2 different circuits of TDA2003. This will result in a 20Watt amp. so to power this amplifier your Current rating of the supply should be double as compared to 1 circuit.
- for a 12V converter your current rating should be 1 Amp for 1 Circuit
i.e. converter max output current should be 2 Amp for a dual channel amplifier.
Moreover the datasheet specifies a peak current of 3.5A can be drawn from the battery


- for a 12V converter peak current rating should be 3.5 Amp for 1 curcuit

i.e. converter max output current should be 7 Amp for a dual channel amplifier.


To sum it up generally the amplifier works on a range in the middle of ideal and Peak values. So roughly around 12V-3Amp converter would be decent. however the more the Amps the better the beats will be as the beats tend to draw more current.


2 years ago

I made the amplifier 2 times, but none of them works. I powered them with 9V first of all, the speaker starts to make a popping noise, then nothing. No voltage to the speaker. What may be the problem?

3 replies

Reply 2 years ago

okay, I am not exactly sure what went wrong but lets figure it out.
1 - when u make a circuit did you solder the IC ? never do that If u did It might damage the IC.
2 - check all other components are soldered properly.
3 - before soldering did you perform the continuity test of the PCB?
4 - are you using a good quality power supply? i.e. is it capable of delivering about 2 Amp max current at 9V?
5 - If all the above is okay then i guess we have to debug the whole circuit individually component-wise.
Check and reply about the above mentioned things and we will continue it further :)


Reply 2 years ago

I think the only problem is soldering the IC, because I couldn't find any sockets for an IC with 5 pins. I thought this may be the problem


Reply 2 years ago

Sometimes you have to work around stuff.. If you look closely I myself cut a regular IC socket for lets say 6-8 pin IC in the middle and used that as a socket for 5 pin...


2 years ago

thanks for the very quick reply.

i dont have any 12v battery so i cant test it but i can either do it with 9v battery.

otherwise i like to build a amplifier using a premade module that i can buy from ebay to my pc.bcos these amps wont a another powersupply. so i can make a usb powered amp using premade amp.

1 reply

Reply 2 years ago

You can test it with a 9v battery too. or simply test with any car battery that is normally 12V. With 9V battery if you increase the volume the distortion will occur..
You can get pre-build amps but they are not fun as I like to build my own stuff. USB power amps will never give you more than 5W output ideally.. it will be always less than 5W.