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16 to 4 line encoder

Discussion in 'Datasheets, Manuals or Parts' started by danuke, Nov 8, 2007.

  1. danuke

    danuke New Member

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    does anyone know of a 16 to 4 line encoder and part number? It can be either cmos or ttl. I've searched google and here and didn't come up with anything. If something exists like this please let me know.

    All help is appreciated.

    Thanks,
    Joe
     
  2. blueroomelectronics

    blueroomelectronics Well-Known Member

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    Never seen such a chip. Wonder how would it handle more than one high input at a time?
     
  3. danuke

    danuke New Member

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    Not sure on the more than a single high part. Basically looking for something like a BCD encoder or a 10 to 4. I'm actually just looking at using 12 of the inputs, not all 16.
     
  4. dave

    Dave New Member

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  5. Pommie

    Pommie Well-Known Member Most Helpful Member

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    ONLINE

    Have a look at the 74148 - 8 to 3 priority encoder. If I remember correctly there is some way to cascade them.

    Alternatively, it can be done with a diode array. Tie each output low and have a diode from each input to each output line that has to be high.

    Mike.
    Edit, google priority encoders.
     
    Last edited: Nov 8, 2007
  6. nickelflippr

    nickelflippr Member

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    Harris HD0165
     
  7. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi,
    Look at the HEF 4532 , 8 input priority encoder, you cascade two of these ic's to give a 16 bit encoder.
     
  8. on1aag

    on1aag New Member

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  9. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi on1aag,
    You must visit my workshop [museum] , I have got about 4 or 5 on the shelf!:p

    Actually they are 4*4 [x,y] scan matrix to a 4bit output with a strobe, used on keypads.
     
  10. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    That's what the 74C922 was, a keypad encoder.

    Perhaps the OP might like to mention what he wants it for?.
     
  11. blueroomelectronics

    blueroomelectronics Well-Known Member

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    I've seen the 74C922 on the University of Toronto PIC demo board. You can still get them but they cost more than a PIC 16F628A would (that could replace it, and offer more features too like key rollover and buffering) and enough I/O left over for a buzzer :)
     
  12. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi Bill,
    I would agree they are expensive, I wouldn't recommend them for a new design.
    However, I have seen 2 or 3 members asking for information on the ic.
     
  13. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    I suspect it's mainly because they look in the old databooks, or google for keypad encoder, and this is what pops up.
     
  14. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    The members asking the questions have also been in the 'developing' countries, I wonder if its the 'time shift' factor on obsolete components?

    Actually, the 74C922 is/was an excellent device, its just the price thats counts it out, never had one fail!

    There are lots of posts ref 741 opa, I expect the hedgerows of the world are littered with 'old' devices.
     
  15. Leftyretro

    Leftyretro New Member

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    It reminds me of the robust business on E-bay for Nixie tube displays. Seems that many want to build digital clocks using these old displays even though it's really old tech and can take quite a few bucks gathering all the high voltage parts and such. I use to have tons of that old stuff around but somehow between home moves most is gone. Still have lots of mid 80s and on stuff.

    Lefty
     
  16. danuke

    danuke New Member

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    I'm using it to encode 12 pushbuttons into a 4 bit code. It's not for a keypad per say but something similar. It's just going to take the 12 pushbuttons and make it into a 4 bit binary value so that it can be used with less traces to be run, etc on a pcb.
     
  17. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Obvious method would be to use a PIC to do it, and either run four traces as planned, or even one as a simple serial interface. You've not mentioned what the rest of the project is?, but it's probably also simpler to replace the rest of it with the same simple PIC? - or a couple of them?.
     
  18. danuke

    danuke New Member

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    I really don't have any experience in PIC work. I've been thinking about diving into that world, but really don't know what type of programmer chips etc would be a good starter kit.

    I pretty much know when I get into that, I'd want to use flash based PICs for learning on so I can play around without spending several dollars per chip. If you happen to know of an easy programmer to learn on, please feel free to recommend one. I'd like to try to stay under $50 for a whole kit (1 flash chip, programming hardware, and software) if possible.
     
  19. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Check out the InchWorm, an ICD2 clone - cheap and VERY capable.
     
  20. danuke

    danuke New Member

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    does the inchworm+ come with the components and circuit board or just the circuit board?
     
  21. blueroomelectronics

    blueroomelectronics Well-Known Member

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    If you're using USB then I'd recommend a Junebug, the kits come with all the parts.

    Since dipmicro does not carry the Junebug I'll see what I can arrange with Creatron Inc (they have stock both kit and assembled)
     

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