for making a relay to ON after 45 secs & another to get on for only 20 to 40 secs

Discussion in 'General Electronics Chat' started by gopi_electron, Feb 1, 2008.

  1. gopi_electron

    Thread Starter New Member

    Feb 1, 2008
    9
    0
    Dear Experts,
    I do need an idea for making a relay to ON after 45 secs & another relay to get on for only 20 to 40 secs. The working voltage for the circuit is 12VDC.
    Also i have no knowledge of ON/OFF delay timers, pl hel me!
     
  2. DrNick

    Active Member

    Dec 13, 2006
    110
    2
    So you want a relay to activate 45 seconds after another relay has been activated for 20 seconds?
     
  3. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    1,437
    1
    you can use a dual timer like the LM556. both timers configured in a monostable mode. the 1st set t 45 seconds and the other one having a selector switch to represent your 20 to 40 secs on time. however both timers are activated at the same time.

    or maybe you want the 1st timer to activate the 2nd timer at the end of its time count.

    moz
     
  4. gopi_electron

    Thread Starter New Member

    Feb 1, 2008
    9
    0
    sorry sir i did not post clearly, i should keep the circuit in a most vibrational circumstance such as diesel genarator. will the ic based circuit reliable ? to such circumstance i never tried pl help me!
    also in that circuit each relay is used for safetys in the the machine so that on and of time of each relay will be independant and based only on the sensor they are connected and used for trip protection
     
  5. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    National Semiconductor makes a MIL-SPEC version of the 555. They call it "MNLM556-X"
     
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