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Laptop to car speakers curcuit board

Discussion in 'Automotive Electronics' started by PaulD, Jul 23, 2004.

  1. PaulD

    PaulD New Member

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    Hello all,
    I took electronics in ’89, but I still remember a lot, and still know how to solder. That being said, what I want to do is build a cheap circuit board for my car. The purpose is so that I play audio from my laptop over my car stereo speakers. What I imagine as the final product is a stereo cable from my laptop to a stereo connector on a circuit board. From there I will need to amplify the signal to play over the car stereo speakers. I will control the output with my laptop. My speakers are stock so I only need 4 to 8 watts. I plan to splice all the speaker wires coming out from my car stereo, and soldering them to the circuit board. From there, there will be some kind of auto-switch that will automatically switch to my laptop input when a signal is detected, and then switch back to car stereo when signal is absent. Cool huh. This sounds like it will be a lot of fun, and hope it won’t set me back any further than about $20. Your help will be greatly appreciated. Thanks.

    Paul

    BTW, there is a crude drawing here:
    http://home.comcast.net/~manva/index.html
    No laughing, I’m a computer geek, not a EE.
     
  2. Exo

    Exo Active Member

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    Well, a nice little +- 8 watt amplifier can be made using a TDA2003. It's meant for car audio purposes, so it can be ran of 12V directly.

    here's the datasheet for it
    http://www.electro-tech-online.com/custompdfs/2004/07/tda2003.pdf
    There is a working scematic in the datasheet on the bottom of page 1.

    You'll need to make 2 of 'em, for stereo (or 4 if your car has 4 speakers).
    You can use the headphone output on your laptop as input for the amps.

    The simplest way to switch the signal is probabely by using a couple of relays. Don't forget to switch of the power of the tda2003 amps if you're listening to the radio (or they'll just be wasting power)...

    As for a signal detecting (for auto switching), I have a scematic for such a thing lying around somewhere, I'll see if i can find it.
     
  3. PaulD

    PaulD New Member

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    Thanks EXO, you’re awesome. I'll look for that signal sensing schematic when you find it. In the mean time, I'll work on this amp. Thanks again.
     
  4. dave

    Dave New Member

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  5. Exo

    Exo Active Member

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    Here's the scematic for the audio signal detector. It outputs a voltage around 2.5Volts when an audio signal is applied...

    You'll need some logic circuitry to make this work. If there is a pause in the audio (a silent moment) then it will see this as 'no signal' and the output will be gone.
     

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