Multimedia boombox with microphone inputs

Discussion in 'The Projects Forum' started by SReeves, Sep 3, 2014.

  1. SReeves

    Thread Starter New Member

    Sep 3, 2014
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    I am trying to make a self-contained music system for my little girls for Christmas. It's something that I know they'll enjoy, and I will enjoy building. The problem is I know hardly anything about circuitry. Detailed below is my objective, and this is a request for help with the wiring aspect.

    The following requirements items can be prefabricated, and purchased, so long as I am informed how to connect them to the system.

    Component requirements:
    - Speakers (2x: 6-8" woofers, 2x: tweeters)
    - Multimedia reader (SD and flash)
    - Microphone inputs (2x: 6.5mm or 3.5mm)
    - Master volume controls (x2: 1 for music, 1 for microphones)
    - Auxiliary input (3.5mm audio)
    - Voltage regulator

    Function requirements:
    - Music and microphones: individual volume adjustments
    - Music and microphones: individual master volume adjustments (parental control)
    - Microphones usable while music is playing (obviously)
    - Accept dual voltage (120v/240v; I'm a US citizen living in Germany)
    - Main power switch
    - Fuse

    Optional (Fun) functions:
    - Music-reactive LEDs
    - Microphone-reactive LEDs

    Please, any help would be greatly appreciated. It would seem that some of you geniuses out here would have something along these lines already in your project arsenal. I can follow a *basic* diagram, but little squiggly lines and symbols won't mean a darn thing to me, unfortunately. A diagram that includes a legend which specifies precisely the resistors, capacitors, etc. to use is necessary for this project to be a success for me.

    I really appreciate any effort tossed into this idea.
     
  2. wayneh

    Expert

    Sep 9, 2010
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    Since there are commercial products that likely meet your needs inexpensively, and because this is an ambitious project for your professed level, I have to recommend buying instead of building. Save your time and effort (and money) for other activities with the kids. It will cost more to build this than to buy it. Mixing kids and electronics requires attention to safety issues.

    The project is a bit simpler without the SD reader. That's a digital function whereas all the rest could be done in the old fashioned analog world.
     
  3. SReeves

    Thread Starter New Member

    Sep 3, 2014
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    wayneh,

    I appreciate your response. I have searched extensively for a commercially available device that meets all the criteria in my proposed project and didn't find any that were suitable as far as quality goes without spending a small fortune. As for my professed skill level, I am quite versed in electrical applications, but never learned the symbols or their meanings. Please note that I said electrical, and not electronic. For that reason, I do not understand why a resistor would be needed here and a capacitor there. If someone were to provide a diagram that explained in laymen terms what's needed, I could build it without issue.

    To clarify, I don't need to learn to build a transformer, because I can buy one and modify it to suit my project. I needn't understand the inner workings of the multimedia reader, I just need to know how to connect the right wires to the right terminals.

    Perhaps this is too much to ask without having the project underway, but I thought it might be a good place to start.
     
  4. wayneh

    Expert

    Sep 9, 2010
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    Much of what you are describing is an audio mixer, like the "board" with faders that a band might use to balance their vocals and instruments. To specify or build such a thing, you need to know the signals you are dealing with, and the usual approach is to bring all inputs to line level, and then feed that to a power amplifier that drives speakers.

    You've mentioned music and microphones. "Music" is usually line level or headphone level (like what comes out of the iPod headphone port). Digital music is another beast, and not relevant here, right?

    "Microphone" can be a variety of signals. Generally it means a low level signal like a guitar or phonograph that needs pre-amplification to get it to line level. But some "mics" are powered and contain their own pre-amlifiers. And of course there are USB mics. So you need to define what you are planning for.

    Adding sound-reactive lights is relatively trivial and should be no problem. For your power supply, I'd consider using an old computer PSU. You can get one free from the recycle yard, and it'll have all the power handling features you need. Voltage switching, cord, fuse, thermal overload protection, a fan, everything.

    Someone else will need to chime in on the SD port. I have only a vague idea of what you'll need to actually read an SD card (i.e. a computer). Not my wheelhouse.
     
  5. SReeves

    Thread Starter New Member

    Sep 3, 2014
    6
    0
    wayneh,

    Thanks, again, for your reply. I have made a diagram of what I want to achieve. It's a scribbled mess right now, but I intend to clean it up and post it here shortly. Before I read your latest reply, I was thinking about the multimedia reader, and realized that it may require some type of coding, thereby requiring an operating system of some sort, and blah blah blah. Too much work for what I need. Instead, I figured I would just drop an iPod shuffle into the mix. Anyway, let me get this diagram going so I can give you guys a better understanding of my intent.
     
  6. SReeves

    Thread Starter New Member

    Sep 3, 2014
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    Please excuse my rudimentary diagram. I researched on the net a bit and tried to get the symbols correct. The only one that I purely made up is the hexagon, which represents a "Y" (1x 3.5mm female to 2x RCA male). The odd looking piece is an iPod Shuffle. If you don't know what any of the symbols mean, please ask. The symbols came from two different sites, so I am not sure if this is how things should appear. Red objects are components, black lines represent power cables, and blue lines represent audio cables.

    If you are able to read the diagram, without issue, can you identify any potential problems that I might have with the current configuration? Please note that this diagram only depicts one speaker, whereas there will be four. The amp, right of center, will be purchased and the four speakers will connect just as with most amps.

    EDIT: There are multiple potentiometers for the microphones because each mic will have it's own volume, plus a master volume inside the component housing. This is so that I will be able to set a maximum volume that my kids can't exceed. Also, I just realized that I left the secondary (external) volume adjustment off of the diagram, by mistake.

    [​IMG]
     
    Last edited: Sep 5, 2014
  7. SReeves

    Thread Starter New Member

    Sep 3, 2014
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    I may need to run an AC amp to prevent myself from having a power issue when running 4 speakers at volume...

    It's funny that I made that diagram and the more I think about it, the easier this seems. Let's see what I can come up with real quick...
     
  8. bertus

    Administrator

    Apr 5, 2008
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  9. SReeves

    Thread Starter New Member

    Sep 3, 2014
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    Thanks! I will check those out when I have some more time. I woke up late and have to go to work soon.
     
  10. wayneh

    Expert

    Sep 9, 2010
    12,100
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    It depends. You can get a pretty good result with batteries using a modern amplifier design. Look on e-bay or at Parts Express for modular audio amps in the 5-20W per channel (two channels for stereo). These modules are designed for projects like this and they're amazingly inexpensive. I suspect battery power would be fine for little girls that don't need gobs of power and room-shaking low end. It'll probably get used a lot more if it doesn't have a cord.

    Your diagram doesn't really address the pre-amp issue. That's where the signals will come together, get mixed and adjusted to line level for the power amplifier. All those pots would be part of the pre-amp section of your project.
     
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