simple LED with delayed start

Discussion in 'The Projects Forum' started by miha_s, Oct 29, 2014.

  1. miha_s

    Thread Starter New Member

    Oct 29, 2014
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    Hi everyone! I am a newbie in the world of electronics and would like to construct a simple circuit and would like to ask you for some help and advice.

    I would like to build a very simple circuit with a LED light, a battery, ON/OFF switch and what else is necessary. The idea is when you turn it on, the light is off for the first week and starts blinking only in the second week.

    Is it possible to do it and how would you do it?

    Thank you very much for any advice :)
     
  2. Sensacell

    Well-Known Member

    Jun 19, 2012
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    How accurate does the time keeping need to be?
     
  3. ScottWang

    Moderator

    Aug 23, 2012
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    1. What kind of the power supply?
    2. How about the V/I of the power supply?
    3. How about the V/I of led?
    4. How many leds do you like to use?
    5. Do you need the 7-segments led display?
    6. Turn on the switch, leds are off.
    7. Delay for a week. (accurate)
    8. The leds are blinking. (frequency?)
    9. How does the next step?
    a) How long do the leds still keep blinking?
    b) And the next?
    10. And some other things else?
     
  4. wayneh

    Expert

    Sep 9, 2010
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    Is your goal the end product or the fun of constructing it? I ask because it may be easier to use off-the-shelf components to do this project. Like a lamp timer controlling a flashing LED.
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    For simple, could try 4060, 4040, C555 & FET driver for LED. Accuracy maybe a hour or so in a week. First week power drain about 10 mA h, second week 1.7 Ah, so 4 AA NiMh batteries ??
    ? where did this cross out line come from??
     
  6. BobTPH

    Active Member

    Jun 5, 2013
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    It you want any accuracy, a microcontroller with a crystal would be the simplest way.

    Bob
     
  7. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Don't know what you are using as an editor, but your post has strikeout HTML tags embedded in it. I tried a variety of key combinations, but only [ s ]Text[ / s ] worked
     
    Bernard likes this.
  8. miha_s

    Thread Starter New Member

    Oct 29, 2014
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    Dear all, thank you very much for all your useful information! At least now I know in which direction to proceed... Yes, maybe should explain some details:
    - in general thought of batteries, such as xr2032 3V or something similar
    - the idea is that the blinking light would remind my grandpa to check in the fridge for any food going bad. When he checks, then he turns off the device.
    - the accuracy isn't that important, also a day up or down does not change much things.
    Thank very very much again!
     
  9. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Just a couple of ideas.

    A purely hardware solution would take a clock (555), feeding cascaded counters (such as the 74HC4059 presettable counter) to count for a long time - week, and a flip flop/latch to latch the output.

    If you are comfortable with microprocessors, a small one could be programmed to count for a week, timer interrupts/overflow, and turn your LED on. This would result in a small package with few parts.
     
  10. wayneh

    Expert

    Sep 9, 2010
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    How about a magnet on the fridge calendar? I'm just saying there might be some other solutions.
     
  11. BobTPH

    Active Member

    Jun 5, 2013
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    Usually, my nose is the only thing I need to remind me of that!

    Bob
     
  12. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Something like this, if you don't want to go the microprocessor route?
    LongDelayLEDFlasher.gif
    Edit: Schematic and .asc file revised
     
    Last edited: Oct 31, 2014
    absf likes this.
  13. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Thanks! I couldn't for the life of me remember the part number nor name of the 14 stage ripple counter
     
    Last edited: Oct 31, 2014
  14. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Just filling in the numbers from post # 5. I used a 3.3k R & red LED to monitor times. Stage 12 of 4060 = 147.6 sec. or 2 m+ 27.6 sec. Adjusted R3, 30k pot to give this time. Note that R2 + R3 = 160k, when measured = 179k with pot at about 20k. Only 4060 breadboarded. pin 3, 555 might need to go to Q11, pin 15, 4020 to release reset on 555 at count 16777216. Pulse # 2 00001.jpg
    You can use an AC adapter, 4.5 V to 6V, or batteries.
     
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  15. miha_s

    Thread Starter New Member

    Oct 29, 2014
    3
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    oh thank you very much for your help!
     
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