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.
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good day sir, is it okay to use a power supply with 18 volts, 3 amps full bridge rectified.?

usbg3rd (author)  johnrey.valenzuela.515 days ago

good day to u too :) yes a supply with 18v 3A bridge rectifier should work perfectly .. just in case try with a lowest volume and increase it to the maximum slowly ... and if u hear some fluctuation noises from the supply then shut it down immediately .. it wont happen but taking a precaution is good for you, your amp and your supply :)

thank you sir, for answering my question. more powers and project sir. this is so helpful.

usbg3rd (author)  johnrey.valenzuela.514 days ago

my pleasure :) .. and haven't been able to do something in a while... will upload one real soon .. and thank u .. favourite/share/follow :)

What type of socket is the tda2003 plugged into?

usbg3rd (author)  rusty.shackelford13371 month ago

its the Pentawatt package. i dont know if such type of ic-bed exists so i broke an ic-bed and used it for placing my ic in the circuit ...

u can direct solder if u are good at it ... the purpose was that just in case if the IC burns out then i can instantaneously change it without desoldering and then resoldring a new one .

marionddgzmn2 months ago

can you tell me how loud this amplifier can be? and the voltage output

usbg3rd (author)  marionddgzmn2 months ago

loudness is 10w in layman terms its 2x as laptop usb speakers
and voltage output ? what do u mean by it ? it depends on the signal what will the output be.

Soldat75 months ago

Ah the TDA2003. i love this amplifier. Currently in the process to track down proper capacitors for it while designing a PCB for it. Ive experimented a little with the Cx value and learned a little about how capacitor types can influence it. 39nF-ish (most go for either 47n or 33n) is ok for testing, but it can sound a little shrill at times in actual sound as its too low to do its actual job of cutting down the top end in any noticable way(even lets high-frequency noise trough negating its purpose). If you replace it by something a bit bigger (say a 4.7uf cap) the higher trebles get rolled of. which can give a warmer sound it seems. In the end the vallue is open to experimentation. Ive seen 470uf caps getting used as the Cx so its quite safe to try stuff out.

That is what i enjoy the most out of this amplifier. you can toy around with it quite easilly and modify its output in noticable ways.

Soldat7 Soldat75 months ago

Oh and ive toyed around with C4 a bit. Its purpose is mostly to remove any leftover DC element from a AC signal (Class AB amps tend to have a bit of a DC offset which speakers don't like as it can cause them to burn-trough). A smaller C4 causes the bass to diminish. However increasing the vallue (say 2200uf) causes the bass to be increased.

usbg3rd (author)  Soldat75 months ago

I havent tried it yet . the value worked fine for me. but thanks for sharing what purpose it serves. i hope BASS lovers will like it :)

Soldat7 usbg3rd5 months ago

It mostly depends on the speaker size. If a big speaker (like the one you used) is used a big capacitor is probably best. Surprisingly however is that its not the vallue that can have the biggest influence, but the brand. i ordered myself a bunch of those large "Audio" caps used in high-quality stuff just to see how noticable the effect is.

Thank you for inspiring me to get into audio amplifiers (this was the instructable that got me to try the TDA2003 rather then stick with the LM38x series). I'm even tempted to make a sort of follow-up instructable that goes a little more in-depth into how to finetune the amplifier and to reduce noise. By now ive altered nearly every vallue in the circuit with some interesting effects ^^

usbg3rd (author)  Soldat75 months ago

well m glad :) thank u , fav , vote :)

jeuphatos jr.7 months ago
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.7 months 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.7 months 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.7 months 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.

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

usbg3rd (author)  charliemyers1 year 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-ukko1 year 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-ukko1 year 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 :)
yaly1 year 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)  yaly1 year 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 usbg3rd1 year ago
use two 1ohm resistors in series to have a total resistance of 2 ohms, that is the closest I can be !
usbg3rd (author)  yaly1 year 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 usbg3rd1 year 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)  yaly1 year ago
thanks Yaly , Dynamic mic is nice to use ..
usbg3rd (author) 1 year 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
yaly1 year 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)  yaly1 year 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)  golddigger15591 year 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 .
SaurIMX2 years ago
you can use transistors too without using the TDA2003
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