Long duration timer

Discussion in 'The Projects Forum' started by Kefka666, Jul 25, 2008.

  1. Kefka666

    Thread Starter Active Member

    Mar 4, 2008
    38
    1
    I want to make a timer that will run for more than fifteen minutes and power a device (deliver power for 15+ mins and then shut off power to the device). The longest amount of time I can get out of an LM555 monostable is 110 seconds only (using R=1 megaohm, C=100µF). I haven't been able to think of a good alternative. Are there other IC timers that can last longer, or is there a better approach?
     
    Last edited: Jul 25, 2008
  2. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,346
    Hello,

    Another option is an oscillator with a divider and start / stop flip-flop.

    In the link there is a sample with time setting possibility.
    http://www.hobby-elec.org/e_counter.htm

    Greetings,
    Bertus
     
  3. Tahmid

    Active Member

    Jul 2, 2008
    344
    25
    Hi,

    You can make a long duration timer with CD4060 IC and drive the load via a transistor/mosfet/relay. Try by yourself, if you cannot do it, i will try to provide you the circuit i have made.

    Thanks.
     
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