sound ball

Discussion in 'The Projects Forum' started by outlawbrit, Dec 31, 2012.

  1. outlawbrit

    Thread Starter New Member

    Dec 31, 2012
    Hello all. I am looking to develop a ball that speaks sentences when caught as a learning aid for my students of English. I have a spring activated sensor ,
    speaker and battery pack but what i need to know is how to record sentences onto a cuircuit to be played at random. All I can offer for this
    information is my thanks and the knowledge that you'd be making some little Spanish kids very happy.
  2. WBahn


    Mar 31, 2012
    I can't offer up specific chip numbers off the top of my head, but basically what you want is a simple microcontroller, a nonvolatile memory chip, a D/A (find a micro or DSP chip that has one built in) and a speaker (or a suitable piezo element). Then record the sentences you want and store them in the memory chip. Make them all last the same amount of time to keep it easy. Then, in the micro, have a counter that runs continuously and that has as many states as there are sentences (to keep things really simple, make it a power of two, such as 8 or 16 or 32). The counter state will serve as an index into the memory by multiplying it by the length of each recording (if the length is a power of two, this become trivial). When the sensor is activated, the counter state is captured and the corresponding sentence plays. You can keep things really simple by having the micro put itself to sleep if the switch hasn't been activated after a certain amount of time. The next time the switch is activated, it wakes up and starts running again. That way you don't need to have a power switch and don't have to worry as much about it draining the batteries between uses.
  3. elec_mech

    Senior Member

    Nov 12, 2008
    Welcome to AAC.

    How big is the ball? You can buy a premade recording module complete with batteries and speaker for under $15 USD.

    I'm using one now and it's a great little device. You connect it to a computer via USB and load .wav files. It can be set up to play up to 20 different files and will play a different file (in order) every time the button is pressed. You can connect the button to your spring sensor instead. The files can't be made to play randomly, but you're guaranteed to get a different file played everytime the sensor is tripped.

    You would have to record someone's voice via a microphone to a computer then convert the file to something the device can work with (they include links to programs that can handle the converting).

    Here is the device:

    Customer support is excellent as well. One note, do not leave the batteries connected while plugged into the USB. Power from the USB will charge the batteries and destroy them (batteries used are not designed to be recharged). Learned this the hard way.
  4. outlawbrit

    Thread Starter New Member

    Dec 31, 2012
    Thank you so much. I'll now go away and research what you've told me
  5. outlawbrit

    Thread Starter New Member

    Dec 31, 2012
    The ball is slightly smaller than a tennis ball.

    Thank you very much for the information