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4 bit decoder question?

Discussion in 'Electronic Design' started by James Lerch, Nov 21, 2005.

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  1. James Lerch

    James Lerch Guest

    Greetings Gents,

    Simple question. I would like to selectively turn ON / OFF any one of
    16 SSR's using a 4 bit address, obviously I'd use another bit to
    select the state I would like the previously addressed device to have.

    I've been looking at a few decoder / demultiplexers like the 74HCT154.
    I was excited for a moment, but then realized that I'd have to come up
    with a latching scheme for the outputs.

    Do they make a DIP chip that already includes some type of state
    addressable output with out altering the un-addressed states? If not
    any simple ideas on the best way to approach this hardware problem?
    (I'm sure I'm not the first fool to want to do something like this :)

    OH yea, if your curious, I just want to "Geek Out" with Christmas
    lights this year :)


    Take Care,
    James Lerch
    http://lerch.no-ip.com/atm (My telescope construction, Testing, and Coating site)
    http://lerch.no-ip.com/ChangFa_Gen (My 15Kw generator project)
    Press on: nothing in the world can take the place of perseverance.
    Talent will not; nothing is more common than unsuccessful men with talent.
    Genius will not; unrewarded genius is almost a proverb.
    Education will not; the world is full of educated derelicts.
    Persistence and determination alone are omnipotent.
    Calvin Coolidge
     
  2. They sure do. The 74HC259 is an 8bit addressable latch.
    Just select your address, put the data you want on the data input and
    toggle the enable line to set that output without affecting the other
    outputs.
    Make sure you keep the enable input disabled while changing address
    line, otherwise you can corrupt the outputs.

    Dave :)
     
  3. James Lerch

    James Lerch Guest

    Thank You Dave! :)

    I have enough output pins, I can run two of these directly w/o out
    having to do anything fancy. Oh yea, this is going to be fun!

    Thanks again!


    Take Care,
    James Lerch
    http://lerch.no-ip.com/atm (My telescope construction, Testing, and Coating site)
    http://lerch.no-ip.com/ChangFa_Gen (My 15Kw generator project)
    Press on: nothing in the world can take the place of perseverance.
    Talent will not; nothing is more common than unsuccessful men with talent.
    Genius will not; unrewarded genius is almost a proverb.
    Education will not; the world is full of educated derelicts.
    Persistence and determination alone are omnipotent.
    Calvin Coolidge
     
  4. And the problem with a PIC is...?

    --
    Many thanks,

    Don Lancaster voice phone: (928)428-4073
    Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
    rss: http://www.tinaja.com/whtnu.xml email:

    Please visit my GURU's LAIR web site at http://www.tinaja.com
     
  5. Si Ballenger

    Si Ballenger Guest

    If you want to control the 74hct259 from the parallel port The
    below links have some simple info. The bottom link is if you want
    to really get geeky with the christmas lights.

    http://www.geocities.com/zoomkat/status.htm
    http://www.geocities.com/zoomkat/output.htm
    http://www.geocities.com/zoomkat/ppswitcher3.htm
    http://computerchristmas.com/index.phtml?link=how_to&HowToId=4
     
  6. James Lerch

    James Lerch Guest

    Oh Boy :)

    I only have a qty of 52, 30 amp SSRs on hand, but I might be able to
    scrounge up some more off Ebay :)

    I find it funny how a project's mental state goes from "It could be
    done" to "It has been done, and more so than originally thought
    possible"

    Thanks for the links!

    Take Care,
    James Lerch
    http://lerch.no-ip.com/atm (My telescope construction, Testing, and Coating site)
    http://lerch.no-ip.com/ChangFa_Gen (My 15Kw generator project)
    Press on: nothing in the world can take the place of perseverance.
    Talent will not; nothing is more common than unsuccessful men with talent.
    Genius will not; unrewarded genius is almost a proverb.
    Education will not; the world is full of educated derelicts.
    Persistence and determination alone are omnipotent.
    Calvin Coolidge
     
  7. James Lerch

    James Lerch Guest

    None of course, just me and printer ports get a long really good so
    far.


    Take Care,
    James Lerch
    http://lerch.no-ip.com/atm (My telescope construction, Testing, and Coating site)
    http://lerch.no-ip.com/ChangFa_Gen (My 15Kw generator project)
    Press on: nothing in the world can take the place of perseverance.
    Talent will not; nothing is more common than unsuccessful men with talent.
    Genius will not; unrewarded genius is almost a proverb.
    Education will not; the world is full of educated derelicts.
    Persistence and determination alone are omnipotent.
    Calvin Coolidge
     
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