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100 LED Display - Please help, my job depends on it!!

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by leo.j.arnold, Sep 7, 2009.

  1. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    At 20mA per led for 8 led's the specified current rating and dissipation of the 74HCT 164 will be exceeded.
    A suitable shift register would be TPIC6595.

    Compared to the bit switch solution the S/R will be expensive and lack memory retention at power off.:)
     
  2. blueroomelectronics

    blueroomelectronics Well-Known Member

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    It also can't decrement if you press the button too many times.
     
  3. MrDEB

    MrDEB Active Member

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    Thats exactly what I was thinking

    too many presses and the "SB1 rocket" would act like Berni Madoff
    If the op decides to go with the 74164, would my proposal of multiplexing using a 4017 be an option to limit the LED current?
    Sometimes the trees get in the way of seeing the forest
    I vote for the dip switches. Easy, cheap and the entire circuit could be crafted in 2 hours using all dip sockets.
    Bargraph displays, dip switches, resistor arrays.
    Heck the resistor arrays alone would save 90 solder connections. 200 (2 per resistor vers 11 per array)unless you go with 16 pin arrays (14 resistors per dip package)
    The displays if not long enought, just double the number of displays.
    each 20 led display is 50.7mm long x 5 =9.84 inches. If you want a 21inch display (2 LEDs per quota amount no big deal. The displays are end stackable.
    Just need to speed up the multiplexing clock.
    the op has 10 days left!!
     
  4. dave

    Dave New Member

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  5. blueroomelectronics

    blueroomelectronics Well-Known Member

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    A 5V @ 1.2A switchmode wall supply is common and cheap. 100 LEDs at 10mA each is only 1A.
     
  6. MrDEB

    MrDEB Active Member

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    But how bright?

    at 10 ma??
    I like bright LEDs
    lets try 50ma ---lol
     
  7. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi,
    The OP did say 20mA.:)
     
  8. blueroomelectronics

    blueroomelectronics Well-Known Member

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    Well then a 3A wall supply.
     
  9. MrDEB

    MrDEB Active Member

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    For life expectency = 15ma

    sure 20 ma is the norm but 20% or so is perfered.
    You car may go 100mph but do you ever run it to the max??
    In my designs I shoot for 15-18ma max
     
  10. blueroomelectronics

    blueroomelectronics Well-Known Member

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    Modern LEDs are pretty bright with less current than older LEDs. Just get them with a high MCD rating.
     
  11. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    Bill,
    I would use 100 large red marbles in a end lit, clear plastic tube.
    Drop in a marble as required.

    Zero energy.;)
     
  12. blueroomelectronics

    blueroomelectronics Well-Known Member

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    Well the OP better get cracking with whatever design he plans to use. I like the marble idea but I suspect they would get pretty dim after it started filling up.
     
  13. MrDEB

    MrDEB Active Member

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    her are the specs for bargraph leds

    DC20/20SRWA Super Bright Red (GaAlAs) WHITE DIFFUSED 8000 31000 20 Segments
    Bargraph-Displa
     
  14. Boncuk

    Boncuk New Member

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    Not a good question. :D

    My last car (Ford Scorpio) had a max speed of 200km/h resulting in an 8 hour trip from Hamburg to Munich, which meant a bad ratio of travel time vs. work time. (very often a one or two hour job to do)

    After tuning it made 280km/h ensuring a travel time of not more than 5 hours. :)

    Only flying is faster. :D

    Bonuk
     
  15. MrDEB

    MrDEB Active Member

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    yes I have heard of the Autobahun

    supposly has the least traffic fatalities per mile than any other highway in the world
    and an unlimited speed limit to boot
    go figure.
    but then I guess you never drove on a S. cal freeway
    max speed is like 30 if your lucky.
     
  16. Boncuk

    Boncuk New Member

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    I did too, felt like being able to pick flowers on the way. :D

    BTW, speed limit in German cities is 50km/h. Going through Munich at 80km/h police still waves their hands to speed up.
     
  17. Mr RB

    Mr RB Well-Known Member

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    Wow! And I thought Bill's idea was minimalist genius.

    Add a 5w bright red laser shining up from the bottom of the tube to make the marbles glow (and maybe a brightness adjust knob) and that would be a fully workable and visually beautiful display.
     
  18. MrDEB

    MrDEB Active Member

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    Add a pic controlled device

    that drops a marble into the tube, makes the laser blink then an alarm sounds!!
    sounds like a great idea
    lets see you need a pic with software then a 2803 to drive the servo motor that controlls the elevator that gathers up a marble or more as needed then transports the marble/s up to the top of the "SB1" rocket and deposits them
    the laser then blinks by way of a pic comand.
    have a light sensing cell so at night when nobody is at work, the laser shuts off to save energy. Of coarse in the pic code you need to puyt the pic in sleep mode.
    the op had better get cracking and maybe Bill will program the pic for the op
    LOTS TO DO. only 8 days left.
    sure hope parts have been ordered.
    are you sure a 5W laser is big enought?
    maybe program the pic to measure the weight of the marbles and switch on a second and/or third laser according to the weight/# of marbles
    LOL
     
  19. blueroomelectronics

    blueroomelectronics Well-Known Member

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    And it's gotten complex again. K.I.S.S.

    You're right MrDEB, I would have done it with a PIC & a 10x10 matrix for the LED wiring.

    PS firing a laser through glass marbles is not a good idea. Unless you're building a blind-o-matic.
     
  20. MrDEB

    MrDEB Active Member

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    The op would have been better off

    going the pic route.
    would be a simple up count code with option to count down if need be.
    actually the pic would have been easier maybe than the dip switches.
    My question is why did the op start throwing 74164's into the mix?
    going from A to B via C, D, and E. IMO
    I really like the laser idea could be exciting
     
  21. MrDEB

    MrDEB Active Member

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    8 days left!!

    WARNING WARNING
    only 8 days until blast off of the SB1 rocket
    wonder how its comming along
    getting comcerned as we have no contact!!!
     

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