Power my MP3

Discussion in 'The Projects Forum' started by cenee, Apr 21, 2006.

  1. cenee

    Thread Starter Member

    Apr 20, 2006
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    I am looking for a way to power my MP3 player which takes a 1.5 battery every 12 hours. I use it most of the time while working in the computer. So I want to use a usb port to get 5v and lower the voltage by using a 1.5 zener diode (*).
    The problem is that I don't find such diode in the market. How can I regulate the voltage to 1.5?

    (*): 5-1.5=3.5v
    Mp3 draws about 100ma.
    3.5/100ma = 35 hom resistor.
    Rpower= 3.5*100=0.35W, Use 1/2 watts
    ZdiodePower=1.5*100ma= .15w, Use 1/4 watts.
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Use the LM317 regulator, it will be able to power it from USB. You can find the datasheet on AllDatasheet, set it to 1.5V by the resistors as described.
     
  3. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    1,437
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    hi,

    in case you can't tolerate the hum in your earpiece because of the regulator,
    as an added advice, you can pass thru the output voltage from the regulator thru a gyrator circuit to pull down the ripple.

    moz
     
  4. alim

    Senior Member

    Dec 27, 2005
    113
    1
    Hi a diode like 1n4148 nte 519 can pass up to 300 mA , if you series 5or 6 you would get about 3.5 volts drop across the diodes if you place the diodes in series with the MP3 you will have about 1.5 volts for the player.
     
  5. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    1,437
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    hi

    with that configuration, have you considered the noise it will introduce?

    moz
     
  6. alim

    Senior Member

    Dec 27, 2005
    113
    1
    Hi I did not consider noise,but these diodes are low cost and I think worth atry if it does not work he can move on to another idea,but it is certaintly not fatallistic.
     
  7. cenee

    Thread Starter Member

    Apr 20, 2006
    16
    0
    I forgot al about it. Connecting any audio device to a computer means looking for lots of "noise". I tried to power a speaker once and all I got was noise.
    I will try the regulator and Diodes in series, after that I will try to come out with a circuit to lower the noise (don't know how now). (will get back with news in couple of days).
    M
     
  8. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    1,437
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    hi alim,

    of course it's not a fatalistic approach but rather a simple one. as i have said before in my previous response, if he can tolerate the noise well and good for him :D ;)

    moz
     
  9. n9352527

    AAC Fanatic!

    Oct 14, 2005
    1,198
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    Hi Moz,

    I've never tried thing like this before, is the noise really that bad? How about filtering the supply to clean it up? Would it able reduce the noise to an acceptable level? I suppose the noise is due to the unclean USB power from PC instead of the regulation/dropping the voltage, is this right?
     
  10. windoze killa

    AAC Fanatic!

    Feb 23, 2006
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    There are a few regulators on the market that can provide a very clean and smooth 1.8V which is close enough for you purpose. The LP3961EMP-1.8 is a good example. It can provide 800mA which is more than enough.
     
  11. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    1,437
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    hi n9352527

    it's both. filtering it thru a gyrator circuit will clean it down to as much as 10mv. headphones usually gives you the sound of noise you don't usually hear from a baffled speaker although it's there but it's muffed by the environment noise. so if you are used to listening good clean from the mp3 becoz it' battery powered, you will be surprised of what you will hear when you start powering it from rectified ac.

    moz
     
  12. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Why do you think an LM317 will generate (or pass) hum?
     
  13. Arup

    New Member

    Apr 13, 2006
    3
    0
    Hi alim,
    which mp3 player do tou use? If this is a generic chinese mp3 player (s1mp3 player) which functions as mp3 player, FM radio, voice recorder, USB flash disk etc. (generally marketed as fake Sony player) then you can power it using USB port itself. You do not need any thing other. just connect the player in running condition to the USB port and then remove the battery. It should continue playing. and then use the "safely remove hardware" function. and continue using the player w/o any battery. I have one of these players and i use it this way.
     
  14. cenee

    Thread Starter Member

    Apr 20, 2006
    16
    0
    I didn't think of using the MP3's USB port itself to power it; I'll try that.

    I built the circuit already using the LM317 with the proper resistors to get the 1.5V.
    I added a 100uf capacitor at the imput and a 10uf capacitor at the output (as in any circuit). There was no noise at all; it worked. Even, I pulled out the in and out capacitors and still, I didn't have any noise at all (probably because the MP3 has already a filter in it; it has to, since its built to upload the music from the comp.)
    cenee.
     
  15. Excelcier

    New Member

    May 12, 2006
    1
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    Cenee, I also tried this with an LM317 configured for 1.5V for my MP3 player. I measured with a voltmeter to verify it's recieving 1.5V, however, when I connect it and try to power up, the voltage drops to around 0.5V and nothing powers up. I even tried using a potentiometer and scaled the voltage up to as high as 3V without the player hooked up. When I hooked up the player and try to power it up, the voltage drops to 1.5 volts but the player still doesn't power up. After that I popped a battery back in to make sure it was ok and it was.

    I'm thinking the player is looking like it's nearly a short circuit since the implied impedance is so low. I measured the current it draws from a battery at around 0.13A which means that with V=IR, V=1.5V and A=0.13A, R=11.5 ohms

    I think that it's pulling the LM317 down too hard.

    Can anything offer any other ideas? I used a bench power supply with good regulation and dialed in 1.5V and it powered up no problem.
     
  16. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    If you are using LM317L, change to an LM317 that can handle 0.5A or more (see a datasheet). You should have no problems sourcing 130mA.
     
  17. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    the problem is not in the LM317, but in the USB. Older types are rated I guess to 100mA, try to find specifications for USB 1.1 and 2.0. the 2.0 type should be capable of around 500mA.
     
  18. AzBat

    New Member

    May 16, 2006
    1
    0

    Thanks for the post. It helped me out. I have a Creative Labs MuVo TX FM player with 256MB and it's the kind of MP3 player where you have to remove the battery module to plug it into your PC. Once you do plug it in the PC it stops being a MP3 Player/Radio. By using the "Safely Remove Hardware" function I was able to wiggle the MP3 player out of the USB slot enough where I was able to power it on as just a MP3 player. Now I no longer need batteries and I don't have to go through all the trouble of having to build something to power it either. Thanks again for steering me to a solution that works for me. I greatly appreciate it!

    AzBat
     
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