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Author Topic: Radio controlled MP3 player  (Read 1796 times)

flashtwo

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Radio controlled MP3 player
« on: February 20, 2015, 04:29:25 PM »

Hi,

Another winter's project nearly completed.

As part of the Edwardian Steam Launch build (see http://www.modelboatmayhem.co.uk/forum/index.php/topic,37563.25.html ), I want an old fashioned gramaphone with brass horn to be part of the launch.

Well, I've completed the radio-controlled sound system based on a Sparkfun MP3 player.

I've added my own PWM PIC based interface so that I can use the spare joystick channel to give STOP/START and NEXT track control of the MP3 player. The MP3 player has a microSD card on to which the MP3 tracks can be downloaded.

The output of the MP3 player is fed into a 1.5W amp (with volume control) and 3W speaker. The player is provided with a 9-way D-type connector for the PWM signal from the radio receiver and also a serial UART connection for integration with the current Voice Command system being developed (see thread below). The voice control with then give me (I hope!) track selection, volume on/off of the MP3 player.

A relay is included so that an electric motor, connected to the turn-table (no I'm not winding it up!), can be run while the MP3 player is operating.

Currently, keeping with the Edwardian theme, the player has various tunes of Marie Lloyd and Florrie Ford of the 1910s period.

Now, where's that piece of thin brass sheet ......................?

Ian
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henly1234

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Re: Radio controlled MP3 player
« Reply #1 on: July 10, 2015, 04:37:26 PM »

Ah, Im looking at a similar idea, with a couple of flappers dancing to a gramophone playing Charleston music on the boat deck of my Le Sphinx, but the idea of a mp3 player eluded me, what is that mp3 player you use and did you build it yourself?
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flashtwo

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Re: Radio controlled MP3 player
« Reply #2 on: July 10, 2015, 10:39:49 PM »

Hi,

The MP3 player is from Hobby Electronics:-

http://www.hobbytronics.co.uk/mp3-trigger-board?keyword=MP3

and the mono amplifier is :-

http://www.hobbytronics.co.uk/prototyping/mono-audio-amp


I originally controlled the “Trigger” MP3 player from a home made radio control Pulse Width Modulation (PWM)  interface, which controlled STOP/START  and “Play Next” commands.

Having got that method working, my voice control system (see the other thread in this section) advanced to a point where the MP3 player could be controlled by voice command.

I can actually say the name of the tune and the Voice Control System will actually select the track specified, also I have “Play Again” and “Play Next” voice commands to control the MP3 player.

The “Trigger” MP3 player has 18 digital command inputs which can be assigned a control function, so a system with radio-controlled switches can give you an adequate system.

One thing to watch out for is the bits per second recording speed.

This MP3 player is limited to about 180kbps and can cause “warbling” of anything recorded above that speed.

If you have recordings above 180kbps, you can download an App that will reduce, for example, a recording of 230kbps down to below 180kbps and thus stop the “warbling”.

I hope this is useful.

Ian.
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henly1234

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Re: Radio controlled MP3 player
« Reply #3 on: July 22, 2015, 03:34:45 PM »

Thanks for that, Ian, what do need, I already have a Action amp/mixer and numerous spare channels/switches on my f14 navy, so presumably just the MP3 Trigger?

The only thing is that the volume is controlled on the amp and of course all the sounds including engine noise are played at the same volume so if I want to change that I need a stand alone set up like yours?

Would it not be easier to buy a cheap (£12 from Tesco's) mp3 player and adapt that?, but of course I would still need a another speaker.
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henly1234

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Re: Radio controlled MP3 player
« Reply #4 on: July 30, 2015, 12:04:12 PM »

OK, I've got the bits from HT but haven't a clue about wiring,



MP3 Trigger
Mono audio amp breakout
Pololu RC switch with small low-side MOSFET just need a wiring diagram,

Anyone? without going into why I shouldn't be doing this hehe
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