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    In order to create a long duration timer the 556 IC teamed up with a binary divider can provide delays as much as 16 times that set by the time constant of the first timer. You can use two 555 ICs instead of the 556.

    The first timer provides a delay of 7.5 minutes and the divided outputs give a delay of 15 min, 30 min, 1 hour and 2 hours respectively. The second timer is used to obtain the desired output pulse length. Additional dividers may be added to give longer delays.

    If you need a longer duration, for up to 10 hours you can use this circuit www.electroschematics.com/8749/0-3-seconds-to-10-hours-timer-relay/

    Schematic of the Long Duration Delay Circuit

    long duration timer circuit

    Period = 0.7(R1 + R2)C1
    Output Pulse Width = 1.1 x R3 X C5

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    7 Responses to "Long Duration Timer"

    1. Of all of them oldies in ic’s I wonder how many circuits were evolved around this humble chip?

    2. It would easier (and cheaper) to use a simple Picaxe 08M.
      programmable in a few lines of BASIC.

      see tutorial etc, at http://www.picaxe.com/

      cost in the US $2.75
      see https://solarbotics.com/product/28410/


    3. In my country I can build 3 of these circuits for the price of one Pickaxe.

    4. I really meant a Picaxe 08M! 3 x 7493 and 3 x 565 chips will cost me about $2.12 at the present exchange rate. The rest of the components will be a few cents only.:-)

      • You are right about it and indeed most of the projects presented on this website and others can be designed with microcontrollers thus resulting in a smaller and cheaper circuit. The problem is that most of the electronics hobbyist cannot afford programmers or do not know how to program the µC

    5. Sir need 4 digit counter using 7segment display circuit please can you provide me
      The circuit

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