inaccurate long delay with solid state components

Discussion in 'The Projects Forum' started by semegraph, Mar 30, 2010.

  1. semegraph

    Thread Starter Member

    Apr 7, 2007
    I'd like to build a timer to activate a 12vdc fan periodically for short intervals, perhaps on for 10 minutes every interval, with an interval anywhere between an hour or 4 hours.

    Considering the accuracy of the timer is not important, nor the precise voltage produced, I was hoping I could run out and grab some transistors and capacitors from radioshack and throw something together. I'm willing to use ICs if I can pick them up at radioshack, but that seems like overkill for my needs.

    Thanks for your suggestions, everyone at this forum always has such useful guidance, I really appreciate you all helping out those of us who have amateur knowledge of electronics but no formal training.
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    You're not going to be able to make a 1 to 4HR timer with a few components from Radio Shack. Maybe at one time, but not now. :(
    I would just go buy a digital wall plug-in timer switch, plug a 12v wall wart into it, and attach your fan to the wall wart. They usually have a minimum on-time of 1 minute. The motor driven ones generally have an minimum on-time of 15 minutes.