Controlling LED on rocker switch

Discussion in 'The Projects Forum' started by mxw8950, Aug 20, 2010.

  1. mxw8950

    Thread Starter New Member

    Aug 19, 2010
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    I have been working on a project where I need to control the speed of a 12V fan by varying the voltage from 5 volts up to 12 volts. I am using an LM317 in order to achieve a variable voltage.

    I also have a SPST swtich in order to turn the fan on or off. I am using this switch from eswitch

    http://www.e-switch.com/product/tabid/96/productid/113/sename/r1966-series-illuminated-rocker-switches/default.aspx

    With this switch it has four terminals two for the rocker and two for the LED's. I would like the switch to work such that when the fan is on the LED is illuminated.

    The problem I am facing is that since the voltage coming out of the lm317 is variable the brightness of the LED will vary as well. I was thinking of maybe using a voltage regulator off of the LM317 to get a fixed voltage but can't seem to find the right one.

    Would there be a better solution to illuminate the LED on the switch?

    Thanks,
    Matt
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Just use the voltage at the input of the LM317.
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Like this... (yes I left out the circuitry for the ADJ side of the 317, input/output caps,etc...) only the basic details for the question are shown.
     
  4. mxw8950

    Thread Starter New Member

    Aug 19, 2010
    7
    0
    Thanks so much for your response.....I am literally awestruck at how stupid I feel right now.
     
  5. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    Don't worry.. I'll let you know where to send the check.. :)
     
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