1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Personal Project. LED Timers

  1. Apr 3, 2013 #1
    Hi I have a project in mind and I'd like some help starting it up.

    I want to create Twisted Fate's Pick a card, for those of you know the popular game, League of Legends.
    L's are where I'd like to put a blue, red, and yellow LED
    To clarify, All three per L
    The . are empty space

    Basically what I want is a button that i can press which starts the project.
    The lights light up in turn Blue-> Red -> Yellow ->repeat.
    Each light has a 2 second on period before switching to the next light
    The lightshow repeats until 30 seconds is up, then turns off.
    If the button is pressed again, the lights will stop rotating and the light that is on will stay on for the remainder of the 30 seconds.
    Battery Powered

    Question 1:
    I feel like this would be much easier to program than it would be to construct the physical timer.
    Am I right? Or should I explore timers and clocks more.

    2. If programming, what would you suggest I use for the microcontroller?
    If physical, what IC chip do you suggest I use?
  2. jcsd
  3. Apr 3, 2013 #2


    User Avatar
    2017 Award

    Staff: Mentor

    A circuit looks possible - use a counter with resets itself after 2 (so the sequence is 0->1->2->0->...), and power the LEDs according to this output. Use some other system (555 timer?) to switch it off after 30 seconds.
    Button: if the 30s-timer is not active, it gets started (and the counter gets powered); if it is active, the button stops the counter (a second button could be easier).
  4. Apr 4, 2013 #3
    I suggest that you program it, it will be easier and you will have the ability to modify it easily if you want, and for the cost it is cheaper that construct it from separate ic.
    If you decided to program i suggest you use 16f88 microchip micro controller.
  5. Apr 6, 2013 #4
    This can be easily done with microcontrollers.
    Using the datasheet of the microcontroller look for features of timers, timers tend to be more efficient than for loops, this is for the PIC16xxx series. Don't know about arduino though

    This is a cool project i might try this in the Proteus Isis Simulator first if i have time.
  6. Apr 27, 2015 #5
    An extremely simple "old school" method would be to use three or four time-delay relays (surplus price $4-$7ea) and a few regular relays (surplus price $3-$5ea) and maybe a few diodes for isolation, but this method wouldn't be able to do a precision of 2.000s and 30.000s, but the time adjustment of one of the modules I know of (and only $4) is adjustable via a 10-turn pot, and on a 0-10s module, that would give a fair amount of precision.

    I work in aerospace and you'd be surprised at how much logic can be performed using relays and isolation/steering diodes, especially on older airplanes. That method was used all over the place on older aircraft, and a fair amount even up into in the in the '90s... One reason is reliability. Aerospace-grade relays are extremely reliable, fairly cheap (even though what would normally be a $10 relay, may be $200 on up to $1000+), and very simple design effort and qualification testing for whatever project the relay is to be used for. The design and testing effort to use relays to perform a simple task vs. a micro-controller module would be orders of magnitude different... Additionally, when you get into military aircraft, nuclear-hardening comes in to play and this becomes much easier/cheaper with things such as relays. A lot of equipment on some of the Air Force's "most important" aircraft is still operating on discrete components and considerable use of relay logic...
    Last edited: Apr 27, 2015
  7. Apr 27, 2015 #6
    Think about what you are more interested in learning about.
    Circuits or Microcontrollers?

    Doing it with circuits solely is doable, and you'd learn a lot through the process.

    Doing it with a MC would probably be easier, even on just to find guidance and help debugging, and you'd still learn a bit about circuits :)

    If you're really bold you could do it both ways and then let us know which method you enjoyed more :)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook