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Question about currents and flow of electricity

  1. Jun 7, 2003 #1
    I am trying to add an LED to one of my computer parts, but there is not enough current flowing through. I would like to know how to increase the voltage to the LED without messing with any computer parts. I remember something about wires, but i do not remember exactly what to do to increase this flow. PLEASE HELP ME< thanks in advance.
  2. jcsd
  3. Jun 7, 2003 #2
    What computer part are you talking about exactly? I have done quite a bit of computer modding and might be able to help.
  4. Jun 7, 2003 #3
    Its the wire connecting the speaker to your computer, im trying to mod it so that an LED will blink to the sound.
  5. Jun 7, 2003 #4
  6. Jun 7, 2003 #5
    Thats cool, but its not the same, making it is fun. Is there a chance that you know how to increase the voltage though? I have tried a lot of stuff, making multiple parrallel circuits. Could winding the wire around in a spiral make the current stronger?
  7. Jun 7, 2003 #6


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    Unfortunately I do not believe that you will be able to drive the LED (diode) and the speaker on the same line. Something like Gregg pointe you to is the way to go.

    The case speaker is not used that much in a modern system anyway, don't you want to see the sound out of your main speakers, ie the output of the sound card?
  8. Jun 7, 2003 #7
    Thanks for all your responses

    Im still pretty sure that there is a way to do this, because when i raise the volume really really really high (max) the led starts to light up, but it has to be REALLY REALLY HIGH. Im going to try to find something that will increase my voltage. Im pretty sure there is a way, well if i don't get it by this weekend, i can always ask at school, a teacher or something.
  9. Jun 7, 2003 #8
    When the volume is raised enough the voltage produced by the output stage exceeds the forward voltage drop of the LED and causes it to glow. The voltage drops across LED's are fairly constant and depending on the color tend to range between 1.5 and 2.2 volts (red, green).
    You can use a transistor to sample the audio frequency and operate several LED's in responce. Basically you will use the +5 volts supply across the collector and emitter, and the audio will drive the base of the transistor. If you are skilled enough and have access to the parts and equipment I could whip up a schematic for you. How many LED's do you want to drive? (pick a number between one and five)

    Several LED's would work like the display on many pieces of audio equipment, where the higher the volume the more LED's will 'dance' to the music.
    Last edited by a moderator: Jun 7, 2003
  10. Jun 7, 2003 #9
    IM probably going to be using 5 leds, and their all red.
  11. Jun 7, 2003 #10
    Thanks for your replay, thats exactly what im looking for.
  12. Jun 7, 2003 #11
    Do you want me to try and explain it in words? If not I will draw it and email it to you.
    What you are basically doing is using the transistor to send a current down a series of resistors, each one being of higher value than the one before it. By placing LED's in parallel with each resistor, the one across the highest value will illuminate first, then the next highest, and so forth. If you get too 'greedy' with the number of LED's you are wanting to run then you may have to use the 12 volt supply line instead of the 5.
    Also, there are more complicated, and sophisticated, arrangements other than what I'm talking about doing.
    Name your poisen...

    Ok, I have it in a .gif format, ready to send. You need to provide me an email (you can make a 'dummy account' with hotmail if you wish).

    [another edit}
    Check your email for the schematic and instructions.
    Good luck.
    Last edited by a moderator: Jun 7, 2003
  13. Jun 7, 2003 #12


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    Use an voltage gain op-amp with a large current source ability.

    - Warren
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