Led circuit

Discussion in 'The Projects Forum' started by ibigpapa, May 9, 2009.

  1. ibigpapa

    Thread Starter New Member

    May 9, 2009
    7
    0
    I am attempting to create a led circuit comprised of 3 different series of leds. I want the circuit to power on series 1 leds for 5 seconds then power off and series 2 powers on for 5 seconds then powers off then series 3 powers on for 5 seconds then turn off then series 1 2 3 come on for 5 seconds. I'm not really sure where to start with this. I was thinking time delay relays then 555 timer(s) or capacitor and resistor. not quite sure on how to attack it. Would love some ideas or examples of how this would work.
     
  2. Wendy

    Moderator

    Mar 24, 2008
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  3. DonQ

    Active Member

    May 6, 2009
    320
    11
    Several discrete chips, lots of interconnecting wires, resistors and capacitors all over the place, and more trouble than it is worth.

    These days, something like this is so much easier to just put in a PIC. Even with the time it would take to learn to write this very simple program, you would probably come out ahead. Plus, next time you wanted to do something like this, it would go really quickly.

    This task is one that could be done in a single 8-pin 12C508/9 or similar (about 40 US cents). No crystal (internal clock), no capacitors (internal counter/timers), maybe not even current limiting resistors for the LEDs (current limited outputs). You would have the options of changing the sequence or timing based on a switch, or adding more lights, flashing them, automatically resetting them after a timeout, whatever.

    There are free compilers, and some programmers are less than $20.

    Just a suggestion. It would open up a whole new world.
     
  4. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
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    The PICAX is an ideal and un-intimidating way to enter the world of microcontrollers. The Editor/Compiler is FREE and the 8 pin chips are cheap. Once you program an use this chip you may never think 555 ever again.
     
    Last edited: May 10, 2009
  5. DonQ

    Active Member

    May 6, 2009
    320
    11
    Did you really mean "intimidating" ?:eek:


    Sort of the same, but sort of different: Reminds me of a quote from "Calvin and Hobbs"

    "Who would have thought that flammable and inflammable meant the same thing? Boy did I learn that the hard way!"
     
    Last edited: May 10, 2009
  6. mauro.laurenti

    Active Member

    May 8, 2009
    68
    0
    Hello,

    If you use just two strings you are fine just with the 555, till you keep the current of each string within the 555 output buffer limit. Just connect one string with the anode to vcc and the other string with the khatod to ground. The 555 can not obtain a 50% without some additional circuitry beside the Rs and C normally used.

    If you have more than 2 string you can still make a sequencer with multiple 555 (visit the www.ti.com datasheet for the 555).

    Other solution would be a 555 + counter + decoder

    Other solution is a microcontroller.

    For all the solutions keep in mind the output current limit. An external transistor would be probably required for all the solutions.

    Ciao,

    Mauro
     
  7. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    No... Thanks for pointing that out. I corrected it. :)
     
  8. ibigpapa

    Thread Starter New Member

    May 9, 2009
    7
    0
    First of all would like to thank everyone that replied. I've been convinced to move on to the microchip option. Would an avr be a better choice? or is the pic gonna be the easiest as i have less than 2 weeks to get my project finished. The idea is simplistic but now it's off to learn timing with a pic.
     
  9. DonQ

    Active Member

    May 6, 2009
    320
    11
    I think the AVR are generally are a bit more powerful than a PIC. And a PIC only has about 10,000 times the power you need for this application. :D

    I've used both, but if it was me, I'd use a minimal PIC for this application. Inexpensive parts and programmers, and lots of third party support.
     
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