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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. leo.j.arnold

    leo.j.arnold New Member

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    Hello, my boss has asked me to design a 'sales thermometer' to show how close we are to reaching our sales target. I came up with 3 designs, 2 quite basic ones and another one which used 100 LED's which would light up in sequence as we got closer to our target. Unfortunately my boss got very excited about the LED idea and now wants me to make it. I need help!! I've scoured Google for a solution but I can't seem to find what I am looking for. I got as far as linking decade counters together but this only seems to keep one LED lit at any one time.

    What I need is a circuit which will count up through 100 LEDs. The input to advance the count by one would be a push button. But the most important thing is that the previous LED's remain illuminated, so if the count is '9' then 9 LED's are lit up and if the count is '76', 76 LEDs are lit etc.

    Can anyone help me with this or point me in the right direction?? The deadline is in less that two weeks and I'm lost!!

    Thanks in advance
    Leo
     
  2. blueroomelectronics

    blueroomelectronics Well-Known Member

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    Just use ten 10 position DIP switches one for each LED, turn them on in order.
     
  3. thesadman

    thesadman New Member

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    i can do this project for you
    using pic
    just email me
    worldsmart2005
    on yahoo
     
  4. dave

    Dave New Member

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  5. Papabravo

    Papabravo Well-Known Member

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    Seems as though you've been "hoist by your own petard". Why would you have indicated the slightest capability in this regard when you knew you could not back it up. In your defense it might take 2 weeks just to assemble the materials. What does your boss know about such things?
     
    Last edited: Sep 7, 2009
  6. leo.j.arnold

    leo.j.arnold New Member

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    Unfortunatley my A-level in Electronics several years ago led me to believe I would be able to build the circuit easily. How wrong I was!! My memory has failed me and I can't even remember the basics. I also thought my boss would choose one of the more simple designs to save money...
     
  7. blueroomelectronics

    blueroomelectronics Well-Known Member

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    Post your design schematics. What was wrong with a simple DIP switch solution?
     
  8. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi,
    You could use 13, HEF4094 8 bit shift registers, connected in series.
    Set the input to the 1st stage High and clock on each button push.

    Any 8 bit serial in/parallel out S/R would do the job.:)
     
  9. Jonatanboy

    Jonatanboy New Member

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    you could touse some different resistors and some non-temporary buttons and a lot of voltage...(maybe not so much, depends on what kind of LED's)
     
  10. picbits

    picbits Well-Known Member

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    I liked that idea a lot lmao.
     
  11. MrDEB

    MrDEB Active Member

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    depending on how fast you need

    a pic would be most efficient but a 16 position rotary dip switch would be the easy way out.
    another way would be decade counters or several 74154's (count to 16) along with D flip flops(74ls74's). I recall there is a quade flip flop as well??
    have different colored leds for each different goal

    lots of possibilities but how much time to completion??
     
  12. MrDEB

    MrDEB Active Member

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    a serial in parrelle out

    I was trying to remember what it was???
     
  13. leo.j.arnold

    leo.j.arnold New Member

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    It has to be built and completed by September 18th at the latest, so not very long at all. Do you think it is possible??
     
  14. crutschow

    crutschow Well-Known Member Most Helpful Member

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    Just do the dip switch approach, one led and resistor per switch. It's brute force but simple.

    If you can get the parts shortly, it's doable. But you'll probably be burning some midnight oil.
     
  15. blueroomelectronics

    blueroomelectronics Well-Known Member

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    A typical rotary switch is often a one of x selector (only 1 LED at a time).

    Why would your boss care how it's done? The end result would be the same.
     
  16. leo.j.arnold

    leo.j.arnold New Member

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    Yes I think for simpplicity and speed of production I will probably go for the dip switch solution. Just working out now how to neatly conceal the wires going to each LED...unfortunately there are no PCB production facilities in my office :(

    Thanks for all your answers guys, unless anyone has any other speedy suggestions I'm going to go with the dip switches.
     
  17. colin55

    colin55 Well-Known Member

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    Here is a really simple solution.
    Put 3 LEDs in series and connect them to a 1k resistor and a 12v supply. Do this 33 times.
    Put a tiny jumper link behind each LED, on the back-side of the display.
    At the start, no LEDs will come on.
    Cut the jumper across a LED to turn it on.
     
  18. MrDEB

    MrDEB Active Member

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    only takes 20 miniutes to etch a pc board

    for ease of mounting all them LEDs, you could go with SMT.
    download express pcb, order some Pulsar paper or just look on Ebay for LED displays--lol
    the SMT would be fast so the holes wouldn't need to be drilled.
    you have 10 days to get it working and tested.
    Where you located?
    If I was home I would be happy to do your boards as I have 8 boards with 2 oz copper on them that are not real useful for thin traces.
    BUT I am in Washington, Not Idaho right now. Sorry
    Am sure some one here could do your boards = easier than hard wiring.
    Unless a pc board manfacture can get a 24-48hr turn around.
     
  19. 3v0

    3v0 Coop Build Coordinator Forum Supporter

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    You can easily build this one on perf board or proto board with a copper donuts around each hole.

    The LED and other component leads can be solder together on the back side. Only the components will show on the top.

    If you were carfull soldering you could possibly just punch the parts through a sheet of foam core and make a good looking display. I would use a bit of alu foil as a heat shield when soldering ;)

    3v0
     
    Last edited: Sep 7, 2009
  20. MrDEB

    MrDEB Active Member

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  21. Boncuk

    Boncuk New Member

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    Hi,

    bosses tend to be wise guys.

    Using DIP switches (mice piano) your boss might try to cheat the circuit by closing any of the switches resulting in an odd looking display with a gap in between.

    Using ten rotary switches (cheaper than DIP-switches) there must be a logic sequence when switching one more LED in sequence. This sequence is achieved by carrying the supply voltage from one switch to the next only when that particular switch has reached position 10.

    Any turn on the following switches will have the LEDs lit in count up order without any gap.

    Also, a rotary switch with a big knob would probably be more convienient for the "operator" instead of searching for the switch on a mice piano. If he has "sausage fingers" he'll hit two or three switches simultaneously. :)

    I made a PCB design for you (completely single sided) using 100 single LEDs.

    Board size is 395X75mm.

    If you want to use it please PM me your email address. I'll do some cosmetic works at the PCB design and send it to you asap.

    Boncuk
     

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