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comparator problem

Discussion in 'Electronic Basics' started by sk, Nov 3, 2004.

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  1. sk

    sk Guest

    Hey
    I'm actually designing a comparator circuit


    |--------feedback resistor------|
    | |
    | |---------------------| |
    RC CIRCUIT ----|------|+ | |
    | COMPARATOR CIRCUIT | |
    INPUT----------|- |--|---------OUT
    |---------------------|
    The task is to design this cirucit in such a way that when an input
    pulse (0.5,-2.5) with a pulse width of 8micro seconds is given it
    should produce me an output which remains high for atleast like
    64micro seconds..i tried using R=2248.5k and C=8500pF and the feedback
    resistor i used was 90k..i was able to get an o/p which remains high
    for 64microseconds but when looked at it carefuly i was able to figure
    out that the outout remained high just beacuse of the large difference
    between the resistors(the storage capacitance is not much observed in
    the o/p graph)...it should basically work like a monostable
    multivibrator (without using ic 555 timer though)...it would be of
    great help to me if u could give me some suggestions as how could i do
    this..

    thanks
    sk
     
  2. john jardine

    john jardine Guest

    Homework or not, I needed a rest from programming a damned PIC and as a
    starter, suggest this ...
    Should give a -repeatable- timed pulse of about 65uS.

    +5V +5V +5V +5V +5V +5V
    | | | | | |
    .-. | --- .-. | |
    | | | --- | | | |
    | |1k | 1n| | | | .-.
    '-' | | '-'10k | | |
    || | ___ |< | | | | |1k
    o--||--o-|___|--| BC556 | | | '-'
    IN || 10k |\ | | |\| |
    o 1n | | o----|-\ |
    | | | | | >--o---o
    | '------o----------|+/ OUT
    | | | |/|LM393 o
    | | | | |
    | .-. .-. | |
    | | | | | | |
    | | | | | | |
    | 56k'-' '-'6k8 | |
    === | | | |
    GND === === === ===
    GND GND GND GND

    (created by AACircuit v1.28 beta 10/06/04 www.tech-chat.de)
     
  3. john jardine

    john jardine Guest

    [clip]

    No good. Belay that. I Didn't read the question. The 8uS input pulse is the
    critical feature.
     
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