MP3 or Cell Phone Amp

Discussion in 'General Electronics Chat' started by Bill Holben, Feb 13, 2012.

  1. Bill Holben

    Thread Starter New Member

    Feb 12, 2012
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    Are there any simple but good schematics for a stereo amplifier with bass using the LM386 IC?
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    I think the data sheet provides what is best.
    As for bass u need a tone control circuit. or a bass booster RC circuit of some kind.
     
  3. Bill Holben

    Thread Starter New Member

    Feb 12, 2012
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    Thank you. Do you know where I can find some good schematics?
     
  4. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    I built the circuit shown below to use with my MP3 player. It works well enough, and I use it daily, but it is not high fidelity. The LM386 is not a top end amplifier.

    As you can see, I only wanted mono. To get stereo, you would need to eliminate the audio signal combining resistors R1 and R2 on the front end, and just build two separate amplifier circuits, one for the right and one for the left channel. I did not include a volume control on the amplifier, but rather use the volume control on the MP3 player.
     
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  5. Audioguru

    New Member

    Dec 20, 2007
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    Its tiny 220uF output capacitor cuts frequencies below 91Hz so there will be no deep bass sounds.
    Its 0.1uF supply bypass capacitor is good for high frequencies but the supply voltage will be jumping up and down at low frequencies.
    With a 9V supply its output power into an 8 ohm speaker is only 0.45W at clipping which is flea power.
     
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  6. Bill Holben

    Thread Starter New Member

    Feb 12, 2012
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    thank you. I tried using the tea2025 but I couldn't get it to work. I'm sure I am doing something wrong. The radio shack here has a crappy selection of op amps. I'm just looking to build a nice sounding amp thats easy and affordable. can you help? thank you
     
  7. Audioguru

    New Member

    Dec 20, 2007
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    There are many power amplifier ICs available. I order ANYTHING online from Digikey or Newark. If I order before 8:00pm then it is delivered to me the next morning.

    You must determine if you want a wall wart power supply or a battery.
    You must determine how much maximum power you want from each channel.

    The datasheet for the TEA2025 shows a simple stereo amplifier and a simple bridge amplifier.
     
  8. Bill Holben

    Thread Starter New Member

    Feb 12, 2012
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    I tried building that tea amp and I just couldn't get it to work. I am new at all this electronic stuff. It started as just a fun hobby and now it's an obsession. What I am trying to build is a amplifier for my cell phone and it's going to be atached to my bicycle. I want it somewhat loud with good bass. I am also trying to put a 16x4 lcd display in it as well to display song titles and radio frequencies and its all going into a walkman size tape recorder housing. I have been working on it for about 3 months and really have not gotten anywhere. Not as easy as I thought. If you have any suggestions I am all ears. thanks.
     
  9. Audioguru

    New Member

    Dec 20, 2007
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    First determine how big a battery you want.
    Then determine how much power you want that also affects the battery voltage required.
    Then pick an amplifier IC that will do it.

    There is not much space on a bicycle so I guess the speakers will be tiny and will not produce deep bass sounds. Boosting the bass sounds might not do anything except waste battery power.
     
  10. Bill Holben

    Thread Starter New Member

    Feb 12, 2012
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    It looks like its going to be 9v. I'll be using 2 six ohm,six watt speakers that came from a high end radio alarm clock. I know i will be going through batteries like crazy but I haven't seen a small 12v battery. The only electronic store nearby is radio shack and they have a crappy selection of amps. I wish I could use the tea2025 but i'm not that good figuring out the schematic. is there an easier one? i have included the data sheet for the tea amp. it's the only one I can find and it's the one I can't get to work.
     
  11. Audioguru

    New Member

    Dec 20, 2007
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    You selected an unknown maufacturer of the TDA2025 IC. Its designation numbers on the schematics do not line up with the parts so it is hard to see which part is which. The schematics from name-brand manufacturers are clearer.

    There are two amplifiers shown, a mono bridged higher power amplifier and a stereo amplifier. Which one did you try?
     
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