How to make leds flash for 20 seconds and then turn off

Discussion in 'The Projects Forum' started by clockmaker, Jan 15, 2008.

  1. clockmaker

    Thread Starter New Member

    Jan 15, 2008
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    I am building a clock. I am a good artist/designer/woodworker...but not a very good electrician. I have built a clock with a train theme. Inside I have installed a quartz clock movement with a built-in trigger switch which turns on "train sounds" on the hour. The train sounds are created from a small circuit board kit powered by 2 "AA" batteries. I have also incorporated a momentary pushbutton switch to enable playing of the train sounds whenever I want to hear them. This all works great. The train sounds play 20 seconds and then shut off automatically.

    I also installed flashing lights on this clock, on a R/R crossing sign, and on a couple of locomotives, etc. It is a flashing light kit, on a small pcb, which alternately flashes led's. It is powered by a 9 volt battery, and is turned on and off with a pushbutton switch.

    Here is the problem I hope someone can help me with: I would like to have the flashing lights turn on at the same time as the train sounds, flash 20 seconds and then shut off. Will a capacitor combined with a resistor work to control this type of circuit? Also, can the trigger switch on the clock movement fire both circuits? Any advice would be greatly appreciated.
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
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  3. algae

    New Member

    Jan 14, 2008
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    Here's another website too, that has a "dummy alarm" project which is basically the same thing, i.e. it flashes an LED on and off with a certain frequency using a 555 timer chip:

    http://www.kpsec.freeuk.com/projects/dummy.htm


    That site has a lot of good beginner electronics stuff too. You can pick up a 555 timer at radio shack (I just bought one the other day). It is possible to do without a chip, but it's even more complex than this simple circuit in my opinion as it requires transistors as well. But if you really want to do it that way just look up "monostable" on wikipedia and there's a circuit there that shows it. (Not as accurate as a chip, but I assume that doesn't matter here).
     
  4. algae

    New Member

    Jan 14, 2008
    6
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    dummy post...just changing settings
     
  5. clockmaker

    Thread Starter New Member

    Jan 15, 2008
    2
    0
    Thank you for your suggestion about the 555 timer. I will pick one up at my loacal radio shack, and see if I can fire out how to make it control my flashing light circuit. If you are interested I would be happy to send you a picture of the clock I have designed. Just let me know.
     
  6. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
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    Why not post it here on the forum? Everyone can enjoy it!;)
     
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