pulse width modulation

Discussion in 'The Projects Forum' started by 016chris, Nov 20, 2007.

  1. 016chris

    Thread Starter New Member

    Oct 30, 2007
    5
    0
    i am trying to make a dimmer switch circuits using pulse width modulation to dim a 5 volt lamp. The circuit needs to be powed by AAA bateries and power a 5 volt lamp. Can any one recommend any good sights to look for one or email me a good circuit
     
  2. iONic

    AAC Fanatic!

    Nov 16, 2007
    1,420
    68
    Incandescent lamps are very sensitive to changes in the supply voltage. These characteristics are of great practical and economic importance. For a supply voltage V,

    * Light output is approximately proportional to V
    * Power consumption is approximately proportional to V
    * Lifetime is approximately inversely proportional to V 16
    * Color temperature is approximately proportional to V 0.42

    Not that you need all this info. There are a gazillion sites dealing with PWM and lighting.

    You might want to study the data sheet for the LM555 Timer. http://cache.national.com/ds/LM/LM555.pdf in particular the monostable mode.

    Also: check out this article: http://electronicdesign.com/Articles/Print.cfm?ArticleID=11028
     
  3. GS3

    Senior Member

    Sep 21, 2007
    408
    35
    The first one is notoriously false. I went to Wikipedia to check and saw you copied from there but left out the exponents.
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    With a five volt lamp, a pot changing base current into a transistor should be all the control necessary.
     
  5. GS3

    Senior Member

    Sep 21, 2007
    408
    35
    Except that the OP explicitly asks about doing it with PWM and also there is a question of using AAA batteries anda 5 V lamp which I am not quite clear about.

    And then there is a question about "good sights" which I am not sure how to interpret. ;)
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
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    I believe that might be "good sites".
     
  7. 016chris

    Thread Starter New Member

    Oct 30, 2007
    5
    0
    yes sorry that is what i meant good sites
     
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