Laptop MP3 radio transmitter

Discussion in 'Wireless & RF Design' started by pieman, Jun 1, 2008.

  1. pieman

    Thread Starter New Member

    Jan 26, 2008
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    is it possible to connect something to a laptop that transmits MP3 files that can be picked up on a radio? I work in a kitchen and we have a radio that plays CDs but doesn't have any where to plug an MP3 player into. After a few months the radio has started to get a bit boring and I'd much rather listen to my own music. I tried taking my laptop into work but the speakers aren't powerful enough to be heard across the kitchen (its an Asus eee PC, wonderfully portable but not too big in the screen/speaker areas)
    The only way I can think of getting my music out of the radio speakers is by transmitting it via radio waves.
    So the main point of this thread...
    Is this going to be feasible and can you point me in the direction of some further reading?
    I'd much rather learn how to and make something like this then just buy a ready made gadget.

    I'm fairly competent with electronics and computing and all ways eager to learn something new.
    Thanks alot
     
  2. Externet

    AAC Fanatic!

    Nov 29, 2005
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    Yes.
    I have a couple of tiny transmitters that plug to a player earjack and transmit on 3 metres FM to my car radio receiver or any other. Can be plugged to your laptop audio out, and probably powered from the USB jack.
    Miguel
     
  3. pieman

    Thread Starter New Member

    Jan 26, 2008
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    Thanks for the fast reply. That's definitely reassuring. Does anyone know how to make something like this? I'm also a little bit concerned that a homemade transmitter may be illegal. Has anyone else in England ever had experience with this?
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    I believe the xmitter Externet referred to uses the Bluetooth protocol, not at all good for picking up on the broadcast band.

    If you had a Radio Shack to visit, the easy way out would be to get an IR headphone. The headphone out of the portable would drive the transmitter, and the receiver could be patched into the stereo. Don't know about butchering into the radio receiver...
     
  5. Externet

    AAC Fanatic!

    Nov 29, 2005
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    Last edited: Jun 1, 2008
  6. beenthere

    Retired Moderator

    Apr 20, 2004
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    Well, I get to learn something a feel a bit silly, too!
     
  7. boogieman

    New Member

    Jun 2, 2008
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    If you would rather build something... DC Kits has a couple for about $30...

    I have one of the "stereocasters" hooked to a whip antenna in my upstairs window (tuned to my freq) on a 12v wallwart. I can roam around on my bike about 1/8 mile radius and hear it quite clearly on my pocket FM radio.

    One thing is it uses a decent modulator IC (JRC's NJM2035 vs ROHM's BA1404) and thus has a lot better sound quality than the BA1404-based units.

    I believe that DC Kits also has the units available preassembled. If you's want something with a bit more power you can look into NRG or Veronica overseas. Their 50-100mW units can easily cover a square mile with a decent antenna.

    Then there's a guy on eBay who builds AM STEREO (C-QUAM) transmitters as well as conversion kits for a lot of mono AM radios.... I've been SO tempted to try one out but they're around $200!

    HTH

    Boogieman
     
  8. Audioguru

    New Member

    Dec 20, 2007
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    Hi Boogieman,
    The Rohm BA1404 stereo transmitter IC is obsolete and has not been made for about 5 years. It received many complaints about its very poor performance.

    It was replaced by Rohm's much better BH141x series of ICs that use a quartz crystal in a phase-locked-loop frequency synthesizer circuit. some of the ICs use a dip-swich to select the frequencies and others use a microcontroller. The ones with a microcontroller display yhe selected frequency.

    A few years ago, Silicon chip magazine has a project for the 'Micromitter". It is available as a kit in Australia. Nearly all MP3 to car radio FM transmitters use it. A few kits are still available with the awful old BA1404 IC.
     
  9. aidafiza

    Member

    Jun 2, 2008
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  10. Externet

    AAC Fanatic!

    Nov 29, 2005
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    Done, tested, and works.

    Installed a USB connector hooking only the power leads, 3 silicon diodes in series from its +5V to the 3V battery terminals in the irock gadget and transmitted internet streamed audio from my compfuser to the home stereo.:)
     
  11. pieman

    Thread Starter New Member

    Jan 26, 2008
    5
    0
    So the plan will definitely work then. I am planning to actually make a device to transmit the signal, rather than buy a premade gadget but due to time constraints will probably have to wait until the summer before I can start to think about it seriously. I'll probably move the discussion over to the project thread when I've got more of a plan.
    Thanks for all your input
     
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