Delayed start

Discussion in 'General Electronics Chat' started by TheDag, Jun 4, 2013.

  1. TheDag

    Thread Starter Member

    Jan 1, 2010
    94
    1
    Hi,
    I Have a device that turn ON right after connecting to 5v.
    I Want to delay the "turning on" of the device for 3 seconds...
    I Mean, When plug into 5v, its wait 3 seconds, and then its power on the device....

    Thanks in advance...
     
  2. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    More info on the "device" would be helpful.
     
  3. TheDag

    Thread Starter Member

    Jan 1, 2010
    94
    1
    Its shouldn't matter..., I Just have to delay the 5v input for 3 seconds...
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,002
    3,232
    You could use a 555 one-shot controlling a P-MOSFET in series with the load.
     
  5. Shagas

    Active Member

    May 13, 2013
    802
    74
  6. TheDag

    Thread Starter Member

    Jan 1, 2010
    94
    1
    Thanks,
    There is an easier way? Maybe with capacitor or something?

    BTW, crutschow, Do you have schematic for that?

    Thanks.
     
  7. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    This is where you need to add more info about the "device". Like current draw? Will a slow ramp of the supply voltage be a problem? ....?

    Ken
     
  8. Shagas

    Active Member

    May 13, 2013
    802
    74
    Well the easiest way that I know is by using a capacitor and a transistor
    as in the circuit that I linked
     
  9. TheDag

    Thread Starter Member

    Jan 1, 2010
    94
    1
    its charger, 5v output charger.
     
  10. crutschow

    Expert

    Mar 14, 2008
    13,002
    3,232
    Here's a circuit that is somewhat simpler than the 555 circuit I suggested.

    The P-MOSFET can be any "logic level" type rated for at least three times the current your charger draws.

    R_Ld is just to simulate your charger. It's not part of the circuit you build.

    Power On Delay.gif
     
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