Simple motor time delay circuit

Discussion in 'The Projects Forum' started by friendly_circuit, Jun 19, 2011.

  1. friendly_circuit

    Thread Starter New Member

    Jun 17, 2011
    I'm a mechanical engineer working on designing a simple time delay circuit for a DC motor. I took a stab a designing the circuit and the image is attached. I'd like it to work as follows: When the switch is closed, a small amount of current goes through to the timer. After the time is up, a standard 4 post relay is activated and the motor turns on for some time - 5 seconds or so. After that time the switch opens and the timer resets. The circuit is to launch a projectile which will depress the switch. When it launches, it will open the switch. The timer I plan to use is here:

    I have a couple of questions: Most important - will this work as I described? And the motor lists a stall amperage. Should there be enough power for the stall, or just enough to operator normally? Thanks for any help and suggestions.
  2. #12


    Nov 30, 2010
    1) wrong timer. This one starts "on" and quits later.
    2) The bosses at this site don't like projectile guns. This thread will die a quick death.
    3) All motors draw stall rated current when starting from zero. Just, some of them start so quickly that you can't measure it with a common meter. Be prepared to deliver stall rated current.

    Good bye.

    Senior Member

    Jul 1, 2008
    Sounds like a Rube Goldberg, which are always fun. Problem is.. this statement seems contradictory, unless it's a normally closed switch.