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Retro Drive-in Bluetooth speaker project

Discussion in 'Radio and Wireless' started by Trout Sauer, Jan 29, 2016.

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  1. Trout Sauer

    Trout Sauer

    Jan 29, 2016
    Hello everyone,

    I'm not very great at figuring out how to design a circuit so, I need help rebuilding this old Drive-in movie theater speaker, when I bought this thing someone turned it into a F.M. Radio. I would really like to turn it into a Bluetooth Speaker. So far I've found an old female usb cable stripped it connected it to the battery, then plugged it a Bluetooth USB adapter. It blew up. Any way I'm really lost, and love any advice on how to build a cheap and simple Bluetooth retrofit device.
    I'll upload some pics and pretty please use words that are very easy to understand.

    Thanks for any help.

    image.jpg image.jpg image.jpg
  2. Gryd3


    Jun 25, 2014
    You had a good start... but the 12V Battery will most definitely kill a 5V device... :(
    The easiest thing to do would be using an LM7805. It will take the 12V battery and drop it down to 5V for you... but it will get warm/hot depending on how much power the USB device needs.
    The best thing to do, would be using a 'switch-mode DC-DC Buck Converter'. These are more complicated to build, so it would be best to buy one, but they are much more efficient and run cooler.

    12V into the converter, 5V out which goes to the USB device.

    Honestly, the first attempt was damn close to having a working device... you just missed the discrepancy in the voltage that was needed and the voltage you gave it.
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