Dusk to dawn dimmer

Discussion in 'General Electronics Chat' started by gwbissett, Aug 13, 2010.

  1. gwbissett

    Thread Starter New Member

    Aug 13, 2010
    5
    0
    Hi People

    I am trying to create a dusk to dawn dimmer, the complication here is I dont want to use a light source to control the dimmer cycle.
    I would like it to run a cycle that is adjustable from 10 - 12 - 14 hours and the dimming cycle should be a 1/2 hour on and off.

    In short 1/2 hour to switch the light from off to fully on, 10 hours on and then 1/2 hour to dim the light to off position.

    Can anyone please assist me on this?
    I have thought about using automatic speed control or dimmer circuit with a mechanical timer for the 10-12-14 hours switching.

    Thanks:confused:
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    Every 10, 12 or 14 hours you want a light to fade from 100% on to 0% on over a 30min period?
     
  3. gwbissett

    Thread Starter New Member

    Aug 13, 2010
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    Yes

    That is correct.
    It should also switch on over a 30 min timeframe 0% to 100% to start the 10,12 or 14 hours timeframe.
     
  4. gwbissett

    Thread Starter New Member

    Aug 13, 2010
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    A simple ramp up ramp down circuit may work, if I use a mechanical timer for the 10,12,14 hours timeframe.

    I am thinking about using a Op amp as a summer circuit to do the ramping into a Triac.
    But I still need the component to do the summing for the Op amp.
    Thinking about a CD4017 but it does not stay on at the outputs.

    ????
    Any ideas?
     
  5. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    First, lets set the power requirements.

    What type of lamp or LED and how much power must we control?

    If you are using LEDs, we can easily use PWM and change the duty cycle over the 30min from 100% to 0%.

    The timer circuit all depends on the accuracy required. If 10 hours, give or take a few minutes is OK, then a simple 555 timer will suffice.

    You can make a timer with 3 settings.. 10, 12, and 14 hrs, that triggers a flip-flop to know what state it is in...ramp up or ramp down.

    Depending on those results, the dimmer circuit can be controlled.
     
  6. gwbissett

    Thread Starter New Member

    Aug 13, 2010
    5
    0
    Hi

    Thx for the assistance so far, I am more interested in the ramp up and down module of the dimmer, how do you create an automatic dimmer, that will only need a signal to dim or bright?

    I want to dim and bright a 230v lamp.

    Regards
     
  7. gremlin

    New Member

    Jul 22, 2010
    19
    2
    use a siemens logo logic module .. verry easy to program and has full pwm output for your dimmer time limmits and analoge inputes for a LDR for dusk dawn sensing
    plus hundreds of other functions

    do a google search for siemens logo
     
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