12v 555 timer circuit 1-5 minutes with motor

Discussion in 'Homework Help' started by HarrisonRedwood, Apr 5, 2016.

  1. HarrisonRedwood

    Thread Starter New Member

    Feb 9, 2016
    I need to make a variable timer circuit using a 555 timer that I can control to be on for 1-5 minutes. I have posted a picture of where I am so far but the problem is that the 12v motor stays on until the power is stopped. The potentiometer doesn't seem to do much. I'm not sure what the problem is?

    Also is it OK to run the motor and circuit from the same power supply or should I use a relay between them?

    Help is much appreciated, cheers. 555.jpg
  2. Bordodynov

    Well-Known Member

    May 20, 2015
    The Resistor by value 1MegOhm change on 10kOhm. The Potentiometer 10kOhm change on potentiometer 1MegOhm.
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012

    You are changing series resistance from 1,000,000M to 1,010,000M. That is hardly any change.
  4. #12


    Nov 30, 2010
    You could run into leakage problems with the capacitor. Electrolytic caps that large are not guaranteed to leak less than 8 microamps.
    If the capacitor never charges up enough to flop the output, you know where to look.;)

    Reality intrudes.:(
  5. HarrisonRedwood

    Thread Starter New Member

    Feb 9, 2016
    I have tried making all of the changes said above, however the same problem still remains. The motor stays on forever and doesn't stop, I can't seem to find any solution to it or any similar circuit that does the job.