Help! 555 Timer R1 & R2 Values

Discussion in 'The Projects Forum' started by heedthebaw, Aug 22, 2008.

  1. heedthebaw

    Thread Starter New Member

    Aug 22, 2008
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    Hi!
    I would like to build a small blinking circuit with 2 leds as eyes, I thought about using a 555 with ON time around 6 seconds and off time around 0.2 seconds (not fade) I also thought about using a 20uf capacitor for C1.
    Could anyone tell me what values I should use for R1 & R2 (or C1)
    Another Thought ....
    Would it be easy to insert a LDR somewhere so that it would only work at night?
    Thanks for any help you can give
    Regards,
    Heedthebaw
     
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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  3. kammenos

    Active Member

    Aug 3, 2008
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  4. SgtWookie

    Expert

    Jul 17, 2007
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    See the attached; that ought to do it for you.
     
  5. heedthebaw

    Thread Starter New Member

    Aug 22, 2008
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    Thanks for the quick replies!
    I'll check out the links and thanks SgtWookie for the values, It's exactly what I want.

    Regards,
    Heedthebaw

    :)
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    I have a similar function for Halloween, but I have built a bunch of the circuits with a duty cycle of 30 to 50% and a wide variation of frequencies, all designed to chain off each other so I can use one battery per bush. I deliberately mixed a pile of resistors so they would be semi random. I put them in my bushes around the house, the effect is their full of glowing red eyes. I just love scaring little kids, but I give out good candy. :D
     
  7. heedthebaw

    Thread Starter New Member

    Aug 22, 2008
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    Hi Bill, I want to do something similar, I have a few Gargoyles around the garden and I would like to add the red eyes to them, blinking every so often. As you said, I could put a couple in the bushes for added effect. These would be permanent, so I want to use 12v transformer. I want the yobs to feel that they are being watched and maybe move down the road a bit. (every little bit helps).
    I don't know much about electronics, but I can pick up bits and pieces from the links kammenos & KMoffett gave me.
    Thanks for replying to my post,
    Regards,
    Heedthebaw
    :)
     
  8. Wendy

    Moderator

    Mar 24, 2008
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    I think a fake camera might give them more to pause. Like I said, I aim for mostly off, then fill em up so their are many eyes all over. You might have trouble cutting the bushes back if their filled with wires (think Christmas tree).
     
  9. Audioguru

    New Member

    Dec 20, 2007
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    An ordinary 555 draws current even when it is not doing anything. The battery will be drained.

    You need a more modern circuit.
     
  10. heedthebaw

    Thread Starter New Member

    Aug 22, 2008
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    Hi Guys, thanks to everyone who replied, my "eyes" are up and running inside my gargoyle, and looks good. I'm going to put another pair in another gargoyle, but roughly double the ON time and half the OFF time. I'll just change R1 & R2 to suit.
    Regards,
    Heedthebaw
     
  11. SgtWookie

    Expert

    Jul 17, 2007
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