Reuse an old mp3 player for your halloween projects.


It is a bit of a tradition in the electronics community to make something for halloween. I thought I may as well help some people by sharing a simple hack.

Many halloween hacks and projects incorporate scary noises such as screams and yells. You could use a device like an Adafruit wave shield https://www.adafruit.com/products/94 to do mp3 playback with an arduino but they’re out of stock at the moment. But you really want to get started on your halloween project. Fear not, I have the solution.

Things you’ll need:

  1. A crappy mp3 player. I’ll be using a HY-107 “digital Mp3 player” that I bought ages ago. Sorry, I couldn’t find the manual so I can’t tell you much more. I think it’s an Onix mp3 player. 
  2. Some wire.
  3. A screwdriver.
  4. And whatever else you need for your child scaring halloween hacking fun.

How to do it:

  1. Unscrew the mp3 player’s case. 
  2. Carefully ply the case off the device. Be careful when you do this and watch for any wires sticky-taped to the case of the device. They may rip off the main board if don’t disconnect them from the case first.

    The case half cracked open.

    The case half cracked open.

  3. Examine the board. There should be some processors on the back along with a small battery. On the front there should be some metal discs in the position of the buttons on the case. The metal dics short out metal pads on the board when they are pushed down. This lets a voltage to flow to the chip on the other side of the board and is registered as a button press. The chip then plays a song or whatever else you requested it to do.
  4. Carefully peel the discs off. Keep the discs on the sticky tape in case you want to use the mp3 player again down the track.
    Gently...

    Gently...

    The metal discs on the sticky tape.

    The metal discs on the sticky tape.

  5. Once you have the metal discs off you can test which two pads need to be shorted to trigger a ‘button press’. This can be done using a small piece of wire to short the pads. The red dots show the pads that can be shorted together (at least on my mp3 player) to trigger a button press.

    when the pads marked by the red dots are shorted electrically the mp3 player registers a button press.

    When the pads marked by the red dots are shorted electrically the mp3 player registers a button press.

  6. Now that you know how to ‘press’ the buttons by shorting the pads you can effectively control the mp3 player electrically. Now is a good time to check you haven’t stuffed anything up while opening up the device by plugging in some speakers or headphones and checking that you’re favourite tunes still work. If you don’t have anything loaded onto the device it can still be plugged into the computer as normal. 
  7. Once you have verified that your device can still put out some mad tunes it’s time to rig it up so it can be controlled with any electronics project. That can easily be done by soldering some wire to the pads and hooking the wire up to your electronics project. It’s up to you as to what you want to use to trigger the shorting of the pads.

Cool. There’s a simple hack that allows you to play scary mp3 files with your halloween project. These mp3 players do have a tendency to fall asleep so you might need to send the mp3 player a button press every now and again to keep it awake. Happy hacking!

For those that are interested, the balloon project is waiting for CASA approval. But I’m still building stuff for it.

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