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Simple Adaptive Amplifier Options for Sensor Inter

  • kyson05 Thursday, April 27, 2017 2:41 PM Reply

    I'm building an interface using resistive textile-based sensors that may have different resistance ranges depending on environmental conditions. In order to best make use of my A/D converters, I'd like to explore using an adaptive amplifier that will help compensate for the unreliable performance of the sensors.

    What are my options here? Or can you point me to some references on the topic?

    I can think of two general schemes that would be useful:

    Auto-calibration by finding min and max values in a given analysis window (~30s-2min)
    Explicit calibration using a toggle-to-train interface
    ... Are there alternative schemes I'm not thinking of?
    Some Constraints

    It should be a one-chip solution (small) if possible (like capacitive sensing chips)
    It should be easy to configure and use (I'm not an engineer and I'm not getting paid)
    There will probably be a microcontroller nearby
    Even better would be a do-it-all chip with Wheatstone bridge / voltage divider, lowpass filter and amplifier.
    More About My Particular Setup

    A/D converters will either be the converters built into an Atmel chip (could be ATtiny85 or ATmega32u4 ) or the converters built into an XBee series 2 radio. I've never used dedicated A/D chips before – I'm not sure if there would be any benefit to doing that.
    The sensor will be a piece of polymer-doped conductive lycra from Eeonyx. The resistance changes by about 1 order of magnitude at 30% stretch.
    The whole thing will be mounted on the hand of a performer, so it must be small and physically robust. There's a good chance it will be wireless.
    Precision is important. The interface will be used to continuously vary real time audio effects i.e. it's not a switch.

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