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Sound Circuits

metron9metron9 Posts: 1,100
edited 2005-09-11 14:23 in General Discussion
I am helping a friend with a product he is working on that needs 2 seconds of sound.
He has brought me a device from a toy motorcycle. Tearing it apart it looks like this:

Back: http://www.stickerpub.com/boardback.jpg
Front: http://www.stickerpub.com/boardfront.jpg

This is what it sounds like (recorded 24bit 44k reduced to 8bit 8k) It actually sounds bettter at 8bit 8k than the 24bit 44k recording I made with my studio mic: http://www.stickerpub.com/motor8bit.wav

Waveform: http://www.stickerpub.com/motor8bit.jpg

As you can hear it plays a loop 3 times

What do you think is under the little black epoxy dot on that board? Is it a chip? Can you speculate what kind of chip it might be?

I am looking to play a motor sound with better quality
Could someone give me some options to duplicate this little player and perhaps a 2x or 10x quality improvement circuit as well?

Post Edited By Moderator (Jon Williams (Parallax)) : 9/9/2005 11:28:38 PM GMT

Comments

  • metron9metron9 Posts: 1,100
    edited 2005-09-09 22:30
    Wow all the links got duplicated, gees I cant even post a simple link what is the matter with me? Seems some work but you have to cut and paste the JPG views of the board.
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2005-09-09 22:51
    I cleaned up your links.· Looks like you're a Soundforge user too (I do a bit of video editing and use it for cleaning audio with Sony's Noise Reduction plug-in).

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    Jon Williams
    Applications Engineer, Parallax

    Post Edited (Jon Williams (Parallax)) : 9/9/2005 11:29:35 PM GMT
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-09-09 23:17
    To answer your question, that little black spot is a custom chip on the board designed for that one purpose.· It's epoxied in place.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2005-09-09 23:35
    As far as playing sounds, look into the ISD ChipCorder -- lots of versions available and 8 kHz sampling on some units is certainly better than what your friend currently has. That said, your project will be bigger than an epoxy blob. We use the ISD2560 in our [noparse][[/noparse]coming soon] AP-8 Audio Player (see www.parallaxefx.com).

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    Jon Williams
    Applications Engineer, Parallax
  • metron9metron9 Posts: 1,100
    edited 2005-09-10 03:43
    The cost of that chip is too much at $6.xx. With 60 seconds of sound it's 30 tmes more than I need. The item will retail at $19.99 and we need to keep this aspect of the project in the $1 to $2.00 range. in quantities of 10,000 or so for startup.

    I would like to explore how this device works with the tools I have at my disposal. If I understand the timing and how it generates the pulses analog/digital in a laymans terms it would help.

    Using the oscilloscope connecting the battery on one lead and one of the speaker wires I get the attached output.

    Setting on the scope is 0.1 volts at 50 uS sweep

    So am I correct that this chip is creating a pulse rate of 2,000 cycles per second?

    I don't understand how to read the settings on the uS scale on a 20 Mhz scope I feel like an idiot smhair.gif

    Scope Time/DIV
    50
    20
    10
    5
    2
    1
    .5 = 10 Mhz?
    .2 This must be 20 Mhz ? ( 20 Mhz scope highest setting, just a guess)
    sound.JPG
    640 x 480 - 62K
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2005-09-10 13:16
    If you're going with those quantities then you should contact Winbond (they make the ISD chips, and probably have what you need) directly to see about getting a bondable die -- that's what's under the blob in that circuit you disassembled. You'll also have to provide for an assembly house that can handle that kind of construction.

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    Jon Williams
    Applications Engineer, Parallax
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2005-09-11 14:23
    OK, metron9 --·if your scope is set to 50us in that picture then each major division (i.e. each square) on your scope (horizontally) is 50us, the "sweep speed" is time/division.· Those·"ticks" (negative going spikes) are occurring at a rate of 50us (they're spaced at appx. 1 division.)
    ·
    Frequency = 1 / time; so, 1 / 50us = 20,000 Hz (20 kHz).·
    ·
    But, obviously, there is more going on there than those spikes: it's a "complex waveform", a combination of frequencies.
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