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Need help with a Stamp audio circuit

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  • SN96SN96 Posts: 318
    edited 2006-01-06 17:11
    Sure, I would like to know more about that op-amp Beau.

    Many thanks.

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    Mike

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  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-01-06 17:19
    http://faculty.augie.edu/~dew/311-opamp.pdf

    Last page: "Interchange of R1 and the transistor gives an antilog circuit where[font=TimesNewRoman,Bold] E[/font]out = K log-1 (K
  • pjvpjv Posts: 1,903
    edited 2006-01-06 17:40
    Hi Mike;

    Well, I'm not really frustrated, it may come across that way as I'm trying to help you learn.

    Judging by your pictures, I imagine you are set up to try most simple circuits, and as a separate experiment I wish you would try Ubicom's software A/D. Its only about 6 or 8 lines of code, and it works very well. Study that, and you WILL learn a heap; it is elegant, simple and brilliant.

    I'd be very happy to guide you if necessary......I assure you you will be thrilled with your findings. Then when you feel you have mastered that, you can decide if it applicable to your audio circuit. I suspect it will work well for you as the most significant active bit will be a logarithmic representation of the audio amplitude.

    A further and more in-depth experiment for you, also based on that A/D concept, would be Ubicom's Fast Fourier Transform software. It will give you the amplitudes of several "bins" of audio frequency ranges. This is what I believe you will eventually gravitate toward.

    In the meantime, keep on experimenting, keep on learning, and above all, have fun!

    Cheers,

    Peter (pjv)
  • SN96SN96 Posts: 318
    edited 2006-01-06 18:10
    Thanks Peter,

    Can you point me int the direction of where to find Ubicom's A/D software code example? I can't seem to find it on Prallax's website. I want to check it out and see what I can comprehend from it.

    As always, I appreciate the tremendous help and feedback.

    Thanks

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    Mike

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  • pjvpjv Posts: 1,903
    edited 2006-01-06 18:28
    Hi Mike;

    Actually you can find it on the Parallax site under "Downloads", http://www.parallax.com/sx/downloads.asp it's about the 20th entry down the list names 8bit_adc.src There is a TON of good stuff in that list, including the Tone detection code.

    It's a bit fluffy as it is set in a rather verbose template, but the salient issues are in the ISR. When I get some time this evening I will cut out all the chaff for you and post the bare-bones code; as I said only about 6 or 8 lines after configuring the chip.

    I'm sure you'll be amazed at it's simplicity and elegance.

    Cheers,

    Peter (pjv)
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