School project-Sequental LED Lights

Discussion in 'The Projects Forum' started by rcbob, Aug 6, 2008.

  1. rcbob

    Thread Starter Member

    Aug 6, 2008
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    I’m in 10th grade and have a school project in which I hope someone may be able to help me with, I will try to explain as best as I can. If possible could you explain in very simple terms how I might do it, a drawing would also be great also many thanks in advance.

    The project
    I have 10 LED lights (12volts using a resistor? 3.5 700ma supplied by the light company)
    1-I need a master on/off switch
    2- Lets say Light 1 is on –so when I push a button- Light 1 turns off and Light 2 turns on—When I push the button again lLight 2 turns off and Light 3 turns on-so on. (Only one light at a time will be on .)

    So far this should be simple, ok now for the rest-
    I need 10 on/off switch one for each light so lets say I turn on the master switch and Light 2 on/off switch in the off position, so if Light 1 is on and I push the button Light 1 turns off and Light 3 turns on.

    Another example
    lets say Light 6 is on and Lights 7,8,9and 10 are in the off position so when I push the button Light 6 turns off and Light 1 turns on.
     
    Last edited: Aug 7, 2008
  2. Wendy

    Moderator

    Mar 24, 2008
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    So you want manual controls that also feed back to the automatic sequencer. Sounds like an interesting problem. Aren't you supposed to design it?

    Right now I'm thinking flip flops and AND gates in a ring. This is a pure logic problem, but I'm sure someone will suggest a microcontroller.

    Are there restrictions in the design as far as parts go?
     
  3. rcbob

    Thread Starter Member

    Aug 6, 2008
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    Maybe I shound not have used the word "Sequencer" the lights should only turn on and off with a manual push of a button.
     
  4. RiJoRI

    Well-Known Member

    Aug 15, 2007
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    I think the second part is easier than the first! The switches simply bypass the stage to which they are connected, so that the Stage1 output, instead of being fed into the Stage2 input, is fed into the Stage3 input. Or, the Stage3 input is switch-selectable to get its information from either Stage2 or Stage1.

    --Rich
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    Like I said, gates will do it, the only real question is if this is a homework assignment then I am loath to design it. If this is for a larger project then I would be glad to help. Hints are always acceptable however.

    Why are you needing this design?
     
  6. rcbob

    Thread Starter Member

    Aug 6, 2008
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    Building the lights is not the assignment we are building a school float that needs the lights (It's a game show) So all help is greatly appreciate.
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    Have a look at the attached.

    Basically, it's a 2-person game show circuit. The power switch (S6) and master reset (S4) are at the upper left. Power is applied, and S4 is pressed to reset the game.

    When LD5 (lower right) is ON, the circuit is ready to accept a button push from the two contestants. One contestant has S1, the other S2.

    The first person to hit their switch locks out the other from being able to push their switch and get their LED to light.

    S4 must be pressed to reset the circuit for the next round.

    You could expand the circuit to acommodate 10 players by simply adding more copies of the player circuit.

    Here's a link to a page with several one-of-many type game show timers:
    http://www.techlib.com/electronics/games.html
    I haven't tested any of them.
     
    Last edited: Aug 7, 2008
  8. Wendy

    Moderator

    Mar 24, 2008
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    So are you needing a 10 contestant game show timer?

    The way I interpreted what you were saying is on switch to move the light to the next one in the sequence that is enabled, if it is disabled it is skipped. There are 10 lights. Correct?
     
  9. rcbob

    Thread Starter Member

    Aug 6, 2008
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    Bill, That's it.
    I wished I could have explained it in a few words like you did.
     
  10. Wendy

    Moderator

    Mar 24, 2008
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    OK, I suspect you'll get several ideas in the next day or so, don't commit too soon, some will be closer to what you want than others, not to mention most of them (including mine) won't have been built before.

    I'll start small, 3 lights, the other 7 will repeatitions of the 2nd and 3rd, the 1st one will have to be a little different (home position during power up).
     
  11. rcbob

    Thread Starter Member

    Aug 6, 2008
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    Many thanks in advanced. if you all could please make it as simple as possible, I have very limited electronic knowledge.
     
  12. Wendy

    Moderator

    Mar 24, 2008
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    I'm sorry to disappoint, this is a prime example why a lot of people like microcontrollers. First thing I did was break it down to the following rules.


    Carry out is high when disable is selected and carry in is high OR matching FF is high.

    To accept toggle carry input must be high and enable must be high.

    FF goes low when Previous Carry Out is high and toggle.


    From there I got these schematics. I can put better numbers on them if you decide you want to build it. My first thought is to make the AND gates out of diodes, but the OR gate would have to be a chip.

    You'll note that it is repetitious, the schematic repeats over and over, so it might be possible to build 5 similar boards, each having two LEDs.

    Lucky you (and poor me), my internet was down this weekend, so this was all I had to do (besides job overtime, yard work, etc.).
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    Yep - a uC (microcontroller) is the way to go.

    All the discrete logic IC's get tossed out. Then basically, it's just the LEDs (and driver circuit if necessary), the switches, and the power supply.

    And the programming, of course.

    You could get what you needed with the PICkit 2 Debug Express, $50, from Microchip Inc.
    http://www.microchip.com/stellent/i...deId=1406&dDocName=en023805&redirects=pickit2
    It comes with a PIC16F877 uC on a development board, with a PICkit 2 programmer and software tools for programming it in C and Assembler. There are 35 general purpose I/O pins on the uC, and the development board will give you the places to connect those pins up.

    You can even download MPLAB for free from Microchips' site, and all the documentation you wish.
     
  14. Wendy

    Moderator

    Mar 24, 2008
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    In some ways programming is as hard as building logic, so it really is a choice of what kind of work you want to do. Going from the OP description you need 11 inputs and 10 outputs. You will still need LED drivers if I'm not mistaken too. A casual glance didn't tell me how many inputs and outputs this series could take, but they're not that cheap. They are however, reusable.

    If you were wanting to spend a little more (about a dollar per switch in parts) you could make 10 modules, it is that repetitive. I would estimate each module is going to use two ICs (average cost 50 cents each), 4 diodes, handful of resistors, one transistor, and the LED. It still needs to be breadboarded to verify operation, while I think it would work there are no guarantees.

    One of the reasons I did all the work I did was I like a good logic problem now and then.
     
    Last edited: Aug 11, 2008
  15. rcbob

    Thread Starter Member

    Aug 6, 2008
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    Many thanks everyone I do want to build it-and I need to keep the cost down and I'm no programmer.
    So it looks like Bill's idea is the way to go. Bill could you put the numbers to it and any other detail I might need? It looks like I'm going to need some other help with this since some of its above my head.
    But if I can sweet talk my parents-Is there anybody the would build this microcontroller and program it ? What would the cost be?

    Again thanks
     
    Last edited: Aug 12, 2008
  16. Wendy

    Moderator

    Mar 24, 2008
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    Are you familiar with protoboards? I can lay one out using that, and post it. You can also get solder type boards from Radio Shack. What part of the world are you in, BTW? Radio Shack isn't everywhere, and this tends to be an international forum.
     
  17. rcbob

    Thread Starter Member

    Aug 6, 2008
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    I can order something online if I need to. Also we got a Radio shack 1 mile away. Again Thanks. Again I may need to find some help locally but I would love to learn to do it.
     
    Last edited: Aug 12, 2008
  18. rcbob

    Thread Starter Member

    Aug 6, 2008
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    Bill, Maybe I can get lucky and your internet will go down again. lol
     
  19. dogstail

    Member

    May 8, 2008
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  20. Wendy

    Moderator

    Mar 24, 2008
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    I haven't forgot you, and will work on it. I'm still working a full time job. I'll post them up here as soon as I get them drawn, probably in steps. Are you getting any help (besides here) with the project?
     
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