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Inductor question 2

Discussion in 'Electronic Basics' started by R.Spinks, Sep 21, 2004.

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  1. R.Spinks

    R.Spinks Guest

    I would like to build a circuit which uses a variable inductor as the input
    to set some states for output out of a micro. I was figuring I'd use an A/D
    channel on a cheap micro and output based on the input (the inductor). But I
    don't really know how to set up the inductor for this purpose. If the
    inductor is tuned one way, I'd like the A/D to get X counts and as you tune
    the other way you'd pass through a couple states and end up with the full
    range rail voltage at the other end (so like 5v would be 1 state 2.5v
    another and 0v another). I think I could do this with resistor networks, but
    I want to use an inductor for what I'd like to build. Can anyone suggest a
    relatively cheap circuit which can use the inductor as the input. I can
    input a square wave to the inductor with a 555.. though.. I'm not sure if
    that would work. Since a DC voltage would just be just a short -- I'm not
    sure how to set up the inductor as the input.
  2. CFoley1064

    CFoley1064 Guest

    Subject: Inductor question 2
    If you use an air core inductor with a movable iron slug, you will get a
    variable inductor. If the value of inductance is between 0.5uH and 50uH, you
    can use a circuit like this to find the inductance (view in fixed font or M$

    Q and D Inductance Tester
    3K9 | |
    ___ _V_ | |\ ___
    | 2K 10 turn |/ 330R |
    | | |
    | |\ | |\ ___ |
    o------|H>O-----o----|H>O-|___|- o
    | |/ | |/ 330R |
    --- | | Output
    --- 1000pF | |\ ___ | |\ |\ ___ 10mV/uH
    | '----|H>O-|___|- o-|H>O--|H>O-|___|-o---o
    | |/ 330R | |/ |/ 39K | +
    === | ---
    GND o ---
    | |0.33uF
    C| |
    Lx C| | -
    C| o---o
    | |
    o |
    | |
    === ===
    created by Andy´s ASCII-Circuit v1.24.140803 Beta

    The circuit, which is a mod of an ARRL circuit published a few years back, is
    described at:

    You can place an op amp at the output of this circuit to amplify to full scale
    output as desired. If your inductance is higher, you can play with the R and C
    values to get a wider range.

    Good luck
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