How do I build a device that connects to a computer and broadcasts music to radios?

I want to build a device that will connect to a computer via USB or Serial and broadcast music sent to it to radios. How would I go about this? Is there any software to send music to USB or serial that would work for this?

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FM transmitters have been home built for years. I built one almost 20 years ago from a magazine project. It worked pretty well.

That being said, you have 2 projects you would like to roll into 1.

Step 1. USB audio can be done, but you have to have a good understanding of programming and the operating system. You are better off using a USB soundcard for this portion of the project. Go to any computer sales site such as www.newegg.com and search for "external USB soundcard". It should have a (analog) stereo output (look for headphones on the output).

Step 2. A stereo FM transmitter can be built from kits purchased from stores/sites such as www.ramseykits.com in the USA, www.jaycar.com in Australia, and www.canakit.com in Canada. Search each site for "stereo FM transmitter". You may also do a web search for "DIY stereo FM transmitter" - most will lead you to a circuit that uses the BA1404 stereo transmitter chip. Whatever way you choose to build your transmitter (kit or DIY), you may then plug it into either the headphone jack or your lineout jack. Just remember to heed the warnings about voltage and antenna length, otherwise the radio police (FCC in USA) will be after you.

From the places I told you to go look, you could put together a USB FM transmitter for about $40 US, half that if you go with just the FM transmitter.

Good luck,
Qa
keydogstony8 years ago
Win7Maniac (author)  keydogstony8 years ago
yeah, but do you know how to build one?
PKM Win7Maniac8 years ago
DIY FM Transmitter

via a Google search for DIY FM transmitter

  • If no-one has built a DIY one, it's probably impossible.
  • If someone has built a DIY one, it's probably on the internet.
  • Ergo, instructions for anything you could ever want to build are on the internet. :)
Walke2jd8 years ago
Any reason you cant use a standard audio jack instead of the usb? If so, any fm modulator with an audio in jack will work. If you need more distance so you can reach radios farther than ~10 ft, just solder a long wire to the antenna connection on the board and it should transmit much farther.
If you really must use USB, buy a USB-attached sound device (they're cheap) and connect an FM transmitter to its output jack. Caveat: Legal short-distance FM transmitters generally don't have great sound quality. My own preference is to drop a spare computer at the remote location and retrieve the audio there via network. (Or get one of the network-attached UPNP audio devices, which is basically a dedicated version of that driven from your existing PC.)
Win7Maniac (author)  orksecurity8 years ago
I don't want to buy an fm transmitter, I want to build one. Any idea how? A standard audio jack is fine, even better. (why didn't I think of that!)
Win7Maniac (author)  Walke2jd8 years ago
yeah, a standard audio jack would work as an interface, too, but how would I build the modulator?