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How to Make a Simple Stereo Audio Amplifier Circuit Using IC 1521

A simple stereo audio amplifier circuit discussed here is built around the IC TDA 1521, requires very few external passive components and is able to provide a powerful 12 + 12 watts of music output.
The IC contains all the built in features required for an amplifier circuit like automatic mute, overload and over heat protections.

The circuit of a stereo audio amplifier using IC TDA 1521 presented here is very simple to build, utilizes very few external components and yet is able to produce 12 + 12 watts of hi-fi music power. The input can be from a CD player or your cell phone

Building a stereo audio amplifier usually refers to using two mono amplifiers and integrating their inputs, common ground and the supply to get the required stereo provisions. However such circuits generally tend to become too bulky and moreover making identical modules simply makes everything double and thus the costs involved also get doubled. But there are quite a few single chips available in the market which contains built-in dual amplifier blocks to make things really compact and sleek. One such IC is the TDA1521 which is a dual high fidelity power amplifier chip embedded inside a 9-pin plastic encapsulation. The chip is perfectly suited to be used with rough power supplies and indeed has rugged specifications. We will discuss how to make a simple stereo amplifier using this IC, but before that let’s first go through some interesting specifications of this device.

The TDA1521 basically produces optimum performance with dual supply voltages of around 16 volts and will deliver a good 2 × 12 watts of music thrust into a couple of 8 Ohms loud speakers.

The gain of the amplifier is internally calibrated and fixed at 30 dB with a space of 0.2 dB. This ensures a nice balance of gain in between its two channels.

The chip carries a special in-built music mute facility. The feature enables the IC to disconnect its non-inverting inputs when the supply falls below +/- 6 volts, although the amplifier remains successfully biased at this voltage.

The above property makes the circuit free from unnecessary clicking noises while switching the circuit ON and OFF.

The output of the IC is well protected against overloads and accidental short circuits. The IC also includes a thermal runaway protection so that excessive heating of the IC will not damage it; however it may shut-off at high case temperatures. Therefore it is recommended that the IC is fixed with a heatsink rated at 4K/W when the output is subjected to a 8 Ohm load @ +/- 16 volts supply.

Please note that the pin #5 of the IC is internally linked with the external metal tab over the IC.


The following data provides a few interesting specifications accompanied with this stereo amplifier chip:

Total Harmonic Distortion: 0.5% @ 12 watts,

Quiscent Current Drain is less than 40 mA,

Gain Balance is around 0.2 dB,

Supply Ripple Rejection is around 60 dB,

Channel Separation is @ 70 dB,

Output Offset Voltage is 20 mV,

Power Bandwidth (@3 dB) is 20 to 20000 Hz.


The circuit shown is quite simple and is almost self explanatory. As you can see this stereo audio amplifier hardly requires any components to become a full fledged stereo amplifier. Just a resistor/ capacitor network to handle frequency compensation and a couple of input DC blocking capacitors is all that is needed to generate high quality stereo music from this little package….amazing indeed. The whole unit of this stereo audio amplifier can be easily built over a general purpose board and the whole system along with the power supply may be enclosed inside a sturdy metallic box. Whether it’s your CD player or your cell phone, it will convert every bit of it into a heart throbbing true pulsating stereo output.


  1. hello sir i am glad to meet you here. i have been redirected here from bright hub.i appreciate you for the special circuit request.coming to my problem, i am studying in a college far from my home. it takes 2 hours to go to college by college bus and again 2 hours to come to home.i am feeling bored of traveling. in the bus we wanted to listen music. but volume from the cell phone is not audible to everyone. so i made a amplifier circuit using ic lm386.but the sound clarity and the volume is low.it is producing some other sounds. i want a circuit which gives more volume better clarity and works at 12v or below. i read about the ic tda 1521, but they are not available in our area. so kindly send me a circuit which consists of regular ic's. or even by using transistors which works at 12v or below. thank you

  2. Thank you Harish, Welcome to my Blogspot.

    I'll surely try to find out a suitable amplifier circuit for you and publish it here soon.
    I'll inform you once it done.


  3. Hi Harish,

    Please inquire whether the IC 810 or IC TDA2003 are available in your area or not, because I'll be writing an article on one of these ICs.

    Reply me if any one of these are available, so that I can provide you with the circuit information.


  4. thank you for your fast reply. none of these ic's are available in electronic shops.IC ul2003 is available in our area.i'll try to find this ic 810 or tda2003 in tv and amplifiers shop.

    • Hi Harish,
      Did you go through the link which I gave you? It contains all the information required to build an amplifier using IC TDA2003.

      I'll write the related article on a separate blog which will include only amplifiers, but it may take quite sometime until it appears.


  5. Yes i gone through the link and made the circuit. But i think the sound is low when connected to a 9v battery. Can you publish the circuit which gives more sound and good quality of sound with this ic TDA2003.

    • No circuit can work if the required amount of power is not supplied to it, after all the power in the speaker will depend on how much power you provide to the IC.
      A 9V PP3 battery will never be able to drive any circuit, therefore you will need to increase the power input.
      Use small SMF battery 9 to 12V 1AH for powering the circuit and in order to get desired level of output.

  6. Hai sir .. I am very much interested in assembling circuits but my friends telling it is not possible .. Is it possible for beginners to assemble there circuits.. What will be the average cost?

    • Hi Neil,
      Who told you this?…they are ignorant.
      It does not cost much to procure basic electronic components.
      In India it's very cheap, you can assemble any small electronic project at costs less than Rs 50/-that's $1.
      However, learn the basics first before moving toward practical stuff.

    • Thank you sir ..
      I have done course in mobile service and 5.1 hometheatre assembling is that enough basics. Can i have your mail or facebook id for asking doubts,. Please

    • Hi Neil,
      If you know how to understand and use the basic electronic components then it's enough, probably you should have learned them by now…
      You can correspond in the blog here, our conversation will help to enlighten the other folks also who would be reading the articles…


  7. i need help..
    I bought a sony dvd player .. It has only coaxial output for 5.1audio.. I asked in shop they told to buy amplifier for 5000rs but i already own a home theatre.. I need any assembled pcb or circuit to convert coaxial to analogue.. Please .. Reply

    • Hi Neil,

      I think the circuit can be easily built over a piece of veroboard, because there's hardly any components involved.

      Not sure about a channel separation circuit, I'll to try to find out, though.

  8. hello sir,
    my name is naval singh, and i want to assemble a high quality and high power amplifier for my room, that can give crisp and super clear audio quality(high bass and treble), please suggest me any circuit diagram.
    i will be greatly thankful to you.

  9. hello friend..
    i have a 12v 1Amp transformer and few lm324 and 1c 741 with me. i would like to do a audio amplifier of my can u help me with a circuit using above components.
    thanking u in advance

  10. hey, thank u dude.
    but that circuit is four small speakers and for head phones.
    i have 4 50w speakers. could u pls guide me to make cheap stereo amplifier??

  11. Dear friends i want to make an.audio amplifier at my home in.order to increase my knowledge about amplifier…..pls try to send a practically made amplifier diagram to my mail id mukeshthakur55@gmail.
    Thanks & Regards
    Mukesh Thakur

  12. Dear sir please help me to make an audio amplifier for my mobile…….i want to make this because i want to increase my knowledge about amplifier….

    Please enlist the components and homemade diagram of simple audio amplifire
    Thanks & Regards
    Mukesh Kumar

    • wish you the same

      1)no need of a preamp if the input is from a source such as a cellphone, DVD player, TV, Ipod etc.

      2) did you mean 16 ohms? never heard of 4 watt 1.6 ohms speaker, anyway both can be used here.

  13. thanks for the reply
    no it says here:

    Impedance: 4 ohms
    Rated Input: 1.6 watts
    made in japan
    and its a casio product. A speaker from my mother's piano. :- )

    I have another question.
    1. Can I power the speaker (mentioned above) with 10 watts amplifier?

    • 1. the one which is between bridge is only electrolytic erst all are ceramic disc.

      2. 100K are pots not presets.

      3. the 100k pots are the volume controls.

      4. 10E = 10 ohms, log is the specification of the pots.

  14. hellow sir . i am new to electronics and i have been interested in amplifiers projects which they have been working well . But i have been facing problem of signal clipping mostly on small amplifiers such as tda 2822 even of higher such as tda2040 . how can i avoid this

    • Hello Joshua, are you sure it's signal clipping? Did you check it with an oscilloscope?

      TDA2030 will not have this problem normally, please confirm the fault once again….

  15. Hi sir i am new to electronics. We are asked to make a battery operated dual audio amplifier for MOBILE PHONES in OUR electronic project. The above circuit is fine except that it uses mains supply and a transformer. Please suggest a good circuit with ALL POSSIBLE DETAILS AS I AM NEW TO ALL THIS. Thanks in advance.

    • Hi Kanak,

      you can operate the above circuit with a battery as well, however you will need two 12V batteries and connect them in series.

      just remove the four diode bridge and the capacitor and the transformer and connect the battery as explained below:

      The center series connection of the two batteries will join with the line which is marked with a "ground" symbol.

      positive of the battrey will go to the pin7 of the IC and negative with pin5 of the battrey

  16. Well thnx , but now we are given an amplifier circuit from the net. Its a 20w stereo amplifier using tda7377. They have also used an irf1405 mosfet …. but I dont know why it has been used. I am not getting the irf1405 mosfet anywhere in the market….. what should I do?? Is there any other mosfet which I can use over there? Can u tell me what is the mosfet used as….. a voltage regulator or linear amplifier? Is there any alternative?

    Thanks in advance. Regards.

    • check the datasheet of the mosfet to find its voltage and current specs, any other mosfet with similar rating can be used as a replacement.

      without seeing the diagram I won't be able to suggest much.

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