Relay Delay!

Discussion in 'The Projects Forum' started by NM2008, Mar 17, 2008.

  1. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
    135
    0
    Hi,
    I am trying to set-up a circuit which basically involves a push button switch and a relay.

    What I would like to know is, is there any method of having a 3-5 second delay on the relays switching by using resistors and capacitors, or would a timed latching circuit be needed?

    So the circuit I am trying to figure out is:
    When I push the manual button switch, It would take the relay 3-5sec to switch "on", once my finger releases the push switch the relay returns to its original "off" state immediately, without any delay turning off.

    This circuit sounds very simple but I just cant seem to put it into practice.:confused:

    Thanks for your help!

    Regards NM
     
  2. nomurphy

    AAC Fanatic!

    Aug 8, 2005
    567
    12
    There are timer relays out there (CUH42-30010), but there not necessarliy cheap.
     
  3. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
    135
    0
    Yes they are expensive,
    But there must be some alternative method that can be made up with an ordinary relay?
     
  4. rwmoekoe

    Active Member

    Mar 1, 2007
    172
    0
    i think this circuit may suit your need.
     
  5. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
    135
    0
    Perfect,
    Many Thanks rwmoekoe!!
     
  6. rwmoekoe

    Active Member

    Mar 1, 2007
    172
    0
    :D my pleasure
     
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    rwmoekoe beat me to it ;)

    But as long as I worked it up, might as well post it...

    Attached is a variation; S1 should be a pushbutton momentary. It was easier to model using a SPST ;)
     
  8. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    It's possible to do with one resistor, one electrolytic capacitor, and an SPDT pushbutton. Component values depend largely on the relay's coil resistance, and the pull-in voltage. No claim for compactness here, as a 300Ω relay would require about a 10,000µF capacitor for about 3 seconds. The resistor and capacitor determine the time to discharge the cap before the next delay.

    Ken

    I made a mistake. My circuit does just the opposite, and acts like a monostable. Turns on immediately and turns off after a delay.
     
  9. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
    135
    0
    Thanks for taking time to help me out guys!
    Much appreciated!
    NM
     
  10. ntth_hddl2

    New Member

    Mar 21, 2008
    1
    0
    I have to design a relay digital to protect generator. It has 3 function: stator false ground, rotor false ground, overcurrent stator. Generator is synchro 3 phase.
    Please help me :((
     
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