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Question on Logic Gates

Discussion in 'Electronic Basics' started by vicebay, Oct 27, 2004.

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  1. vicebay

    vicebay Guest

    Hi, I would like to ask if anyone know a circuit or an IC that has
    the following characteristic.

    single input -- single output

    The output should only be triggered by a positive (1) input and will
    not change even if the input changed it state to 0. But when the
    input changed in state to 1 again, the output should change in state.

    I would like to implement this on my design in a sequential light.

    TIA

    -vicebay
     
  2. Rich Grise

    Rich Grise Guest

    The assignment is to implement one with gates. If it
    were me, I'd use a master-slave arrangement, because I've
    never been able to figure out how to toggle one. But I
    can toggle a 2-transistor, emitter-coupled flip-flop.
    Go figure. ;-)

    Cheers!
    Rich
     
  3. Jamie

    Jamie Guest

    yes.,
    they call it a flip flop.
    A D type will work with its DATA
    input connected to an out.
    a RS, or JK also..
    the output will be a logic 5 or
    what ever depending on what family
    of logic chip you use.
    you most likely want to use something
    like a TTL, HC or CMOS into a transistor/
    a HexFet works well for this.
     
  4. Here's a circuit using Jamie's suggested approach:
    http://www.terrypin.dial.pipex.com/Images/4013FF.gif
     
  5. The circuit you describe is known as a divide by two circuit. It's a part of
    almost all counters but can be made easily out of a single flipflop. One of
    the oldest and wellknown is the 74LS74. Although this days a CMOS successor
    like a CD4013B may be a better choice. Just connect the inverted output of
    the flipflop - /Q or an "overscored" Q - to its D-input. Then the Clock
    input of the flipflop is your input and the Q output of the flipflop is your
    output. Hope you have the skills to build your sequential light.

    petrus bitbyter
     
  6. Randy Day

    Randy Day Guest

    But you've got the input connected to the Q output.
    That'll let the magic smoke out.

    I assume you meant for the input to go to the
    clock pin in the middle?
     
  7. "Terry Pinnell" <> skrev i melding

    - cut -
    And this is an alternative:


    .---------------------.
    | |
    | | Output
    | .--o--. |
    .-----. | .-----|J S Q|-----o--------o
    | G | | | -|> | __ __
    |_-_-_|----------o---)-----|K R Q|o ---. __ __ __
    | | | '--o--' |
    '-----'Input | |
    | |
    '-----------------'
    (created by AACircuit v1.28 beta 10/06/04 www.tech-chat.de)
     
  8. Eh, of course. I was a little bit fast here.
     
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