Short Cycle Timer

Discussion in 'The Projects Forum' started by hephaestoskin, Feb 4, 2008.

  1. hephaestoskin

    Thread Starter New Member

    Feb 4, 2008
    2
    0
    Hi, I'm new to the forums, and to electronics in general so please bear with me... I am trying to build a short cycle timer that runs 12v (or 24) but controls a 110v, 125w appliance. It wouldn't have to be variable, 1 min on, 4 min off... and of course it's been 7 years since I touched a soldering iron so I can use all the help I can get. Thanks, I hope I posted this in the right forum......
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    You can use either a triac or a relay to control the appliance voltage with your lower voltage. Timing can be accomplished with some kind of microprocessor or with a 555.
     
  3. mrmeval

    Distinguished Member

    Jun 30, 2006
    833
    2
    Slightly simpler than a triac would be a SSR,
    3-32vdc in and it controls 24-280vac.

    http://www.crydom.com//userResources/productFamilies/23/crydom_ntd.pdf

    You can use a 555 astable to turn on and off a transistor controlling the DC to control it.
    At 5v the SSR only uses about 10ma according to the datasheet. The 555 might be able to directly control it but it would be better to use a transistor.

    http://home.cogeco.ca/~rpaisley4/LM555.html#3

    I've driven this directly from a atmega168 microcontroller. With some i/o extension I could independently control 64 reasonably easy. Each one could control about 20 amps. I won't make one that elaborate but will have a nice lighting display for next year.
     
  4. hephaestoskin

    Thread Starter New Member

    Feb 4, 2008
    2
    0
    Thanks guys! This is VERY helpful!
     
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