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Thread: Planning the driver for the Teensy Audio Board LINEIN

  1. #1

    Planning the driver for the Teensy Audio Board LINEIN

    Hi, I am trying to plan the driver that I should build for the teensy audio board before feeding it with Piezo electric - high impedance sensor,
    my source is a guitar piezo pickup, the impedance is high and not static (because I am gonna move it to a different guitars, which affects the impedance of the piezo sensor...)anyway I am trying to plan an active bandpass filter, cutting all the frequencies bellow 60Hz and higher than 20Khz (for noise cancelling and anti-aliasing)
    I was searching for an OP-AMP that is available in a DIP version so I found this :
    MICROCHIP MCP6024
    and a Digital potentiometer, because I am gonna place the piezo sensors on a different instrument and it will recieve different signal, so I should amplify each of them differently. AD5204_5206.pdf

    I can seen in the MICROCHIP MCP6024 typical applications (A/D CONVERTER DRIVER AND
    ANTI-ALIASING FILTER) Click image for larger version. 

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    Where should I add the low frequencies cutting? (cutoff in 60hz)
    Where should I place the digital potentiometer to control the amp level?
    and which will be the best kind of capacitors and resistors to use?
    I tried to look at the store but there are too many kinds of caps and resistors...

    Thanks in advance!
    Alon

  2. #2
    Senior Member PaulStoffregen's Avatar
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    Nov 2012
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    This circuit will have 1.0 gain for its passband. There isn't any simple way to change the passband gain without altering the filter response. To have variable gain, you'd probably use the e-pot to attenuate the output, and then another opamp as a buffer or amplifier, if you want to have the option of gain more than 1.0.

    Ceramic NP0 or C0G (two terms that mean the same) type capacitors are best for this circuit. They cost a little more than X7R or other types, but not much more for such low capacitance.

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