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

cyberpagan

Mar 27, 2018
3
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Mar 27, 2018
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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
 

duke37

Jan 9, 2011
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Jan 9, 2011
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5,364
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
 

cyberpagan

Mar 27, 2018
3
Joined
Mar 27, 2018
Messages
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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

Where should the capacitors go in the circuit? what type of capacitor?
Thank you so much for the reply.
 

cyberpagan

Mar 27, 2018
3
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Mar 27, 2018
Messages
3
What power sources? Specifics?
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.
 

kellys_eye

Jun 25, 2010
6,514
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Jun 25, 2010
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6,514
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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