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by kanbankaren 12 days ago
You don't even need a Raspberry PI.

You can simplify it even further. List of things you need.

1. Smartphone or DAP.

2. Car Bluetooth FM Transmitter (~$20)

3. USB to 12 V car adapter(~$10)

4. Existing FM radio.

You can set this up in 5 minutes. Connect the smartphone/DAP using BT or AUX cable. Select a free FM channel and you are ready to go.

Also, in the photos, the FM antenna is fully extended which is unnecessary as these FM transmitters put out plenty of RF power.

P.S. On AliExpress, you can buy both for < $15 while on Amazon it is around $30.

P.P.S. Just the USB FM transmitter is only $5 on AE. For the cost of a cup of Coffee!
2 comments
Projectiboga 12 days ago
This isn't an item to cheap out on. Find one with aptX HD support and decent reviews if you have any room in your budget. I use the bluetooth to FM all the time. I have a pair, one in my car and another in my travel kit for rental cars. The key is to find one with aptX HD and other newer hi-fi codecs as there are older chips still being sold with lower specs as BT has been a thing for awhile now. I just did a search are there are ones that are usb powered or wall powered. Another better method might be a real FCC certified FM transmitter that are marketed for Drive Ins and "church parking lots" and use a bluetooth receiver or a usb-dac as the input.
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kanbankaren 12 days ago
You drank the aptX kool aid and forgot the fidelity loss along the signal path.

FM broadcasts do a high pass at 50 Hz and stop at 15 kHz. The best SNR is only ~50 dB which is already achieved by plain old SBC. There is no need for higher fidelity audio codecs like AAC/aptX/aptX HD/LDAC besides the fact that most smartphones don't support aptX or aptX HD.

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Projectiboga 11 days ago
OK, I will hope it is a marker for better tech in the entire product.
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1317 12 days ago
you can make it as cheap or expensive as you want it to be. A big expensive one I'm sure would be better, but you can still be well-served by a £2 usb dongle off wish.com
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qsera 12 days ago
Yea, I did this using a raps-pi as well. Rasp-pi is nice in the sense that it can run a web server to select/enqueue/blacklist/ and what not. I can also ssh to it to download songs and automatically add to the playlist...

Along with the ability to blacklist and add new songs, I hope that I will eventually end up with a huge collection of only the best songs (for my taste)

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