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Retrofitting a vintage radio for blue-tooth playback. Power problems.

Discussion in 'Radio and Wireless' started by cyberpagan, Mar 27, 2018.

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  1. cyberpagan

    cyberpagan

    3
    0
    Mar 27, 2018
    Ok. So I have been trying to retrofit a blue-tooth module into an old transistor radio to turn it into a portable blue-tooth speaker.

    So far I have managed to get the blue-tooth module working with the radio and playing audio out of the speaker but I have run in to a problem that has me stumped.

    The radio runs off 6V and the blue-tooth module can also operate at 6V. Both the radio and the module work fine when separately connected to a power source or a battery but when I wire them to the power source together in parallel neither work. the blue-tooth module even heated up and smoked a little when left wired up for to long.

    Both the radio and bluetooth module work fine together when wired to separate power sources.

    So is there a way to have both the radio and blue-tooth module powered from the same 6v power source with out interfering with each other?

    The model of the radio is: PHILIPS L3Z73T https://images.ehive.com/accounts/3031/objects/images/1rppl9_cnme_l.jpg

    The blue-tooth module is: http://vi.raptor.ebaydesc.com/ws/eB...ategory=44999&pm=1&ds=0&t=1512958894000&ver=0
     
  2. duke37

    duke37

    5,364
    772
    Jan 9, 2011
    Unstabilised 6V supply could easily be putting out 9V, hence the smoke!

    The polarity of the power supply is critical.

    I would link the two devices through capacitors to eliminate DC shorts
     
  3. kellys_eye

    kellys_eye

    4,282
    1,152
    Jun 25, 2010
    What power sources? Specifics?
     
  4. cyberpagan

    cyberpagan

    3
    0
    Mar 27, 2018
    Where should the capacitors go in the circuit? what type of capacitor?
    Thank you so much for the reply.
     
  5. cyberpagan

    cyberpagan

    3
    0
    Mar 27, 2018
    There is a power supply transformer inside the radio that puts out 6V. My intention is to run it off a 6V battery i pulled from an old mobility scooter. All parts work when separately wired to either power supply or battery but then cease to work when wired together.
     
  6. kellys_eye

    kellys_eye

    4,282
    1,152
    Jun 25, 2010
    The bluetooth module will work from 5V plus or minus 5% so it's unlikely the transformer supply will be able to give such an accurately regulated output for that module - hence the smoke.....

    Using a 6V battery would allow you to use a simple silicon diode as a series 'dropper' (it will reduce the 6V to 5.3V) which would be acceptable.

    Have you 'commoned' both the negative supply wires? i.e. the black wires (assuming black/red are neg/pos) of both the radio and the bluetooth are joined?
     
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