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.
the 39nF is difficult to find in our place. can i use other value than that? what could you suggest? if possible in micro nor pico.
usbg3rd (author)  jeuphatos jr.1 month ago

Haven't tried that personally , cant say for sure , but probably a large value wont disturb the circuit but a lower value will. it will not cause your circuit to blow up so give it a shot, see what are the results.

if it works do tell me.

you can also check if the sound quality is UN-acceptable with a different value of Cx then use combination of capacitors (probably in series) to get the required value. :)

thanks for your comment , like and follow :)

I got the exact value you provide but when I made the pcb based on your pcb design you provide..... my capacitor 6 is exploding..... any thoughts?

is the wattage of all resistor 1/2?
usbg3rd (author)  jeuphatos jr.26 days ago

R3 which is 1 Ohm is 1 Watt. make sure it is 1 watt else it might heat up and break their circuit. for the rest of the resistors u can use 1/2 or 1/4 watt resistors.

usbg3rd (author)  jeuphatos jr.26 days ago

what is the input voltage ? are u sure u are connecting the right terminals of capacitor , because electrolytic Capacitors explode when either the voltage is higher than their rating or the capacitor is connected in opposite polarity.

the layout in page 3 is what i mean.

charliemyers6 months ago
You have R3 rated at 1W. Will .25W be sufficient for the remaining resistors?

usbg3rd (author)  charliemyers6 months ago
Yup charlie myers R3 is 1Watt as the resistor has a low value so more amount of current flows throught it and therefore the resistor might get damaged so we use 1 Watt resistor. and the remaining are .25 Watt resistors :) thanks for ur comment.
like and follow :)
pikku-ukko6 months ago
Can I use 50V capacitors for c1 c2 c4 and c5? The store I'm pretty much forced to use atm doesn't have any with smaller voltage.

Forgotten everything about electronics, going to be my first project in about 10 years:D
usbg3rd (author)  pikku-ukko6 months ago
dude, u can use any capacitor with voltage greater than 25V, BUT make sure the capacitance is same as mentioned otherwise the sound might be affected. the voltage rating only means that the capacitor can hold this much voltage across its end and therefore a higher voltage then required will only increase the price of the capacitor slightly :) thanks for ur comment , like and subscribe :)
yaly7 months ago
in the bill of materials you said that R2 = 2.2 ohm while in the schematic diagram R2 = 1 ohm, I build the circuit before noticing this, used R2 as 1 ohm and it sounded great, which value for R2 is correct ?
usbg3rd (author)  yaly7 months ago
actually its is 2.2 ohm but to find a resistor exactly is very difficult as they come in specific values ... so the nearest value i could get was 1 ohm ... and it worked for me too ...
yaly usbg3rd7 months ago
use two 1ohm resistors in series to have a total resistance of 2 ohms, that is the closest I can be !
usbg3rd (author)  yaly7 months ago
lol :P yeah ..
so do you mean i would do it just as shown in the schematic (with the 1 uf cap and 2k2 resistor) but instead of using 9v battery i could use one 1.5v cell?
usbg3rd (author)  Lacrossanator11 year ago
yes but mind that there are different types of mic so pick wisely and do not pic pizzo
the one i used i dont know the exact name or number but it was like
yaly usbg3rd7 months ago
that type of configuration in step 5 is for a type of mics called condenser mic as opposed to dynamic mics which include the piezo/peizo (not pizzo) and these (dynamic) work by generating a voltage on its terminals relative to the sound it receives, while the condenser mics can be said to act as a variable capacitor that changes value with sound, if you are going to use a dynamic mic then connect it directly to the input and gnd of the circuit and dismiss the battery, resistor and capacitor.
usbg3rd (author)  yaly7 months ago
thanks Yaly , Dynamic mic is nice to use ..
usbg3rd (author) 8 months ago
1- first that yes the value should be 44 ohm but u don't get exact valued resistors the nearest value available in the market is 39 ohms .. u can try different combinations (series or parallel ) if u want..
2- c2 c4 c5 cx must be greater than 35V it is because in case if they are not then the output sound might be distorted at high volume .. so its better u use 35 V .. actually it should be greater than the supply voltage so .. suit your self
yaly9 months ago
c4 doesn't reduce the bass as it blocks frequencies from below 20Hz, as humans can't hear them so its not a problem, but it also has to be there to block DC from entering the speaker and so damaging it, you may need to change its value to block below about 10-15Hz if you are using it for a subwoofer
usbg3rd (author)  yaly9 months ago
actually when we talk about BASS its very low frequency therefore capacitor also blocks the low frequency signals . and yes it also blocks the DC to protect the speaker
can a TDA2030av work???
usbg3rd (author)  golddigger155912 months ago
can't say for sure because this circuit is designed for TDA2003. but its circuit looks pretty similar , may be the components values are a bit different u can check the values from the datasheet.
I was just wondering if in the microphone add on circuit, is that two 9v batteries in series for a total of 18V? or just the one 9v battery?
usbg3rd (author)  Lacrossanator11 year ago
boy actually the microphone works on 1.5 or maximum i think 3 volts (depends on mic) and its power consumption is very very low .so u can use 1.5v cells they last so long in case of mic . so no need to build extra circuit to divert power to mic to .. but still u can do it if u like .
SaurIMX1 year ago
you can use transistors too without using the TDA2003
usbg3rd (author)  SaurIMX1 year ago
Making a amplifier with discrete components is the best punishment for anyone =P..
its too dificult to manage all of the transistors and even then all u get is a 1w or max 4w gain ..
if u have any link to discrete amplifier with gain greater than 10W do tell me i want to try one in summer.
2n3055 amplifier :O
usbg3rd (author)  qwerty1561 year ago
i have seen people making circuit from discrete components but when u will build one u will know that its more than 10 transformers that make up one amplifier 2 for the current mirrors 4 for the active loaded differential amplifier this completes one stage then comes the other stage which contains 2 transistors for the current mirror and 2 for providing bulk of gain so it is a HELL difficult making one discrete component amplifier and still u get 2W RMS output with consumption of 12V or greater
usbg3rd (author)  usbg3rd1 year ago
BTW Kid keep on trying for making a discrete one it is an achievement and making amplifiers with ic's Even a Technition can do that an Engineer builds with discrete components
kondzio291 year ago
You should try the TDA1554Q amp 2x22W stereo
only four partsin circuit ;D
usbg3rd (author)  kondzio291 year ago
Nice idea =)
but the IC works at 14V typically and delivers 44W output power which means that it will draw 3.2 Amperes current .. the transformers that are capable of supplying such amount of current are costly ..
B.T.W. it could be a very nice project for a music Lover ; )
why not use a computer power supply?
it will provide a lot of power on 12v
usbg3rd (author)  qwerty1561 year ago
U can use that just note that amplifiers do not draw continuous power so of the computer supply has some protection circuit it may stop giving power to the amplifier continually..
but still u can use that ... i will soon upload another supply circuit without transformer and rectifier circuit .. it will be quiet cheaper and efficient too..

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