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    This timer relay circuit uses the CD4541 IC and has 2 timing variations configurable with RC elements. The specifications of this timer are:

    • modes of operation: astable/monostable
    • the output has a 6A/250V relay with NC/NO contacts
    • LED signals exiting the timing state
    • manual programming done with a DIP-switch
    • 12V voltage operation


    Schematic of the Timer Relay Circuit

    4541 timer relay circuit schematic

    working principle of the timer

    Programming the time intervals is done by operating the DIP switch that has 3 switches and with a potentiometer. Depending on the position of SW1 1 and 2 contacts, the timer can be configurated for the 4 time ranges, as shown in tables:

    0.3 sec to 10 minutes
    SW1 time interval
    1 2
    O ON 0.3s … 3s
    ON O 1s … 10s
    ON ON 10s … 1.5min
    O O 1min … 10min
    15 sec to 10 hours
    SW1 time interval
    1 2
    O ON 15s … 3min
    ON O 1min … 10min
    ON ON 10min … 1.5h
    O O 1h … 10h

    Use the potentiometer for setting the timing period within these intervals.

    For the 0.3 second to 10 minutes timer version the potentiometer is 100kΩ, R1 = 9.1kΩ, R2 = 910kΩ, R3 = 220kkΩ and C1 = 100µF.

    For the 15 seconds to 10 hours timer version the potentiometer is 1MΩ, R1 = 51kΩ, R2 = 1.2MΩ, R3 = 1.2MΩ and C1 = 1µF.

    The operating mode is selected with the third contact of SW1:

    • ON position = monostable
    • O position = astable

    In order to start the timining you have 2 possibilities: you either connect the START point to ground GND and in this case the timer starts when you connect it to the voltage supply or you can place a switch to start it.

    All the resistors are 0.25W and C1 must have a good stability over time.

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    8 Responses to "0.3 Second to 10 Hours Timer Relay with 4541 IC"

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    1. This is a handy gadget for the kitchen I must noiw get the FBI CID M5 AND OTHER SECRET SERVICE TO HUNT DOWN THE COMPONENTS

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    2. Joe Belzer says: on December 30, 2013 at 2:36 am

      What is the box with a line thru it marked rel—

      Is this the output—-

      Thanks

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    3. Martin CZ says: on January 5, 2014 at 7:40 pm

      Hi, I joined scheme but it does not work. If you have connected to the GND pin 7? I have a timer on the button from pin 6 – Must be fixed? Or just simply press and release? What position should be the third option on the DIP switch? And to be when you turn on the relay (minus)? Or occur after the expiry of the timer? Thank you in advance for your answer.

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    4. Anyone has board layout for this project?

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    5. Made it, checked everything 3 times but it doesn’t work. When pin7 is connected to GND LED is very dim, when pin 7 is NC the LED works but it is on all time.

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    6. Martin CZ says: on March 7, 2014 at 5:28 pm

      At least I’m not alone who does not work. I did it on purpose 2 times – 2 circuits and neither one did not. . . .

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    7. As per given datasheet, Initially light off using pull down register to pin 6, When I applied a positive going pulse through push to on switch light continuously ON. Please tell me how to calculate ON time using 4541 IC. Thank you.

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