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    #1

    Building a simple amplifier need help

    So since I'm a complete beginner in electronics I thought I might as well start somewhere and I decided to build a somewhat simple amplifier but some things about the circuit are unclear to me.The amplifier is based on the TDA2030A IC. I chose this amp because I already have the IC at hand. This is the circuit I'm trying to build:

    Website

    Pics of the circuit and PCB


    Datasheet and the same circuit is in the datasheet as an example.

    First of all what types of capacitors should I use for C3,C4,C7 and C8. C1,C2,C5 and C6 are obviously electrolytic.

    Why are C8 and R5's values not given and they are represented with broken lines?

    Can I use a normal PC PSU to power this amp to try it out since PC PSU's have both +/- 5v and ground. (or suggest an unregulated PSU, something simple that I could build.)

    Do I connect the ground from the PSU and the negative lead from the speakers and input to the ground plane of the PCB.

    How do I control the loudness of the speaker? I don't see a potentiometer anywhere on the circuit so I'm guessing it is to be placed between the speaker and the circuit and if so of what values should the potentiometer be?

    Any help is greatly appreciated
    Attached Files
    Guns don't solve problems. I'll take 12
    Tags: None
    #2
    Re: Building a simple amplifier need help

    What is the amplifier for? I can't figure out which is the input and which is the output.
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      #3
      Re: Building a simple amplifier need help

      Originally posted by RJARRRPCGP View Post
      What is the amplifier for? I can't figure out which is the input and which is the output.
      This is a single channel speaker amplifier and Vi is the input and RL is the output.
      Guns don't solve problems. I'll take 12

      Comment

        #4
        Re: Building a simple amplifier need help

        I think I have an amplifier pulled out from a Phillips TV in a box somewhere.

        If I remember correctly it uses either tda2030 or tda2020 - I'll make pictures tomorrow, batteries on camera are dead...

        But if you want to keep it simple, TDA2050 is very nice:



        There's even dyi pages like this one (though the "power supply" they show seems a bit overkill): http://diyaudioprojects.com/Chip/DIY...hip-Amplifier/

        Comment

          #5
          Re: Building a simple amplifier need help

          Originally posted by mariushm View Post
          I think I have an amplifier pulled out from a Phillips TV in a box somewhere.

          If I remember correctly it uses either tda2030 or tda2020 - I'll make pictures tomorrow, batteries on camera are dead...

          But if you want to keep it simple, TDA2050 is very nice:



          There's even dyi pages like this one (though the "power supply" they show seems a bit overkill): http://diyaudioprojects.com/Chip/DIY...hip-Amplifier/
          The 2050 is similar to what I am building. I have 2 IC's available, the TDA2006 and TDA2030A, both of them use the same layout and components for the amplifier and it seems simple to build but the schematics don't show voltage rating of caps, types of caps that should be used, where negative leads should be connected.... Hell I have loads of complicated questions regarding a simple amplifier

          Originally posted by Koda View Post
          First of all what types of capacitors should I use for C3,C4,C7 and C8. C1,C2,C5 and C6 are obviously electrolytic.

          Why are C8 and R5's values not given and they are represented with broken lines?

          Can I use a normal PC PSU to power this amp to try it out since PC PSU's have both +/- 5v and ground. (or suggest an unregulated PSU, something simple that I could build.)

          Do I connect the ground from the PSU and the negative lead from the speakers and input to the ground plane of the PCB.

          How do I control the loudness of the speaker? I don't see a potentiometer anywhere on the circuit so I'm guessing it is to be placed between the speaker and the circuit and if so of what values should the potentiometer be?

          Any help is greatly appreciated

          Feel free to smack me on the head if some of these is insanely obvious
          Guns don't solve problems. I'll take 12

          Comment

            #6
            Re: Building a simple amplifier need help

            The 2030 is a good beginner project, but it sounds pretty bad. You'll want to progress to better stuff in the future.

            As for the other questions, read the datasheet... But this time, i'll help.

            The parts represented with broken lines are optional. They aren't even fitted in the PCB layout as you can see. So, you do not install them. They are needed only in particular situations, and if you follow the datasheet example they are not needed.

            +/-5v isn't even enough for a headphone amplifier. Plus, the negative rails of PC PSUs are really flimsy. Buy a 12-0-12v, 2A mains transformer, you can find one for around $10-$15. Add a bridge rectifier and a pair of 1000uF 25v caps and it should be enough for now.

            The potentiometer is always placed at the INPUT, that is, before C1. I'll let you guess why. Btw, C1 should NOT be a lytic for best sound quality. The 100nF caps can be either ceramic or polyester. They must be placed as close to the IC as possible. Even straight from the power pins, on the underside of the board if you're lazy.

            Power supply ground (in your case it will be the center tap of the transformer), input ground and speaker ground are of course connected together. There are certain rules for that: Power supply ground connects to ground point of filter caps, then separate traces are run from there for signal ground and speaker ground. The signal ground trace must always come straight from between the filter caps, and not have any other part of the circuit grounded to it, as this will induce mains hum into the signal.

            Keep power traces away from signal traces, and also when you progress to more complicated amps with bigger power and some kind of input stage (opamps or whatever), it's good practice to bring heavy power supply traces from the main filter caps to the power section, and then run them to the signal circuitry. The idea is to keep heavy currents away from power supplies and ground of sensitive input circuitry.

            Now of course you have the PCB in the datasheet so all that has been done for you already but it's good to know.
            Originally posted by PeteS in CA
            Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
            A working TV? How boring!

            Comment

              #7
              Re: Building a simple amplifier need help

              I'm not sure but I think the purpose of R5 and C8 is explained in the table at the bottom of page 13.

              Both say in that table at purpose: upper frequency cut-off

              ps.. unique typed all that moments before me... go visit some tv repair guys/ service centers - sometimes they have transformers from tv boards that are too expensive to fix and get one for free..

              ps2... you don't need split power supply, pdf file has versions for both types of supply - but if you make it on 12v not split supply, the tda2030 can probably output 3-5 watts only.

              didn't forget about the pictures, batteries still not charged ... damn 2800 mAh batteries and 8h charger....
              Last edited by mariushm; 10-06-2011, 06:22 AM.

              Comment

                #8
                Re: Building a simple amplifier need help

                That's the simplified explanation. R5 and C8 are placed over the feedback resistor. They form a compensation network which keeps the TDA2030 from oscillating under particular configurations. Yes it is just a glorified lowpass filter - but that's the correct technical naming. They are NOT needed if you follow the datasheet example.
                Originally posted by PeteS in CA
                Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                A working TV? How boring!

                Comment

                  #9
                  Re: Building a simple amplifier need help

                  Well, looks like I remembered it incorrectly... it's actually an amplifier that uses TDA2040...

                  I removed a layer of dust and made a couple of snapshots - if there's interest I can take the board off the wood plank and snap the back of it and more details.

                  The transformer... if I remember correctly is +/- 15-18v, it's been a long time since I actually used this one, now I have 5.1 sound on pc... I think the rating of 35w was for +/- 19v but everything was a gift from a repair guy a few years ago so I couldn't complain then... I remember I was told with the voltages from the transformer the amp could do 20-22 watts.

                  The caps by the bridge are 1500uF, teapo 63v... the caps on the board are mostly Philips on a brief look - figures, being taken out of a Philips tv.
                  Attached Files

                  Comment

                    #10
                    Re: Building a simple amplifier need help

                    Thanks for the help guys, I'll update as soon as I finish the build. Hopefully I won't burn out anything

                    One more thing... For the voltage of the caps, I should be going with any values above what's going in the circuit right?
                    Last edited by Koda; 10-06-2011, 08:20 AM.
                    Guns don't solve problems. I'll take 12

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