Microcontroller light dimmer - amplifying light bulb

Discussion in 'Homework Help' started by markodaguy, Dec 5, 2015.

  1. markodaguy

    Thread Starter New Member

    Mar 24, 2015
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    Hey,
    I need some help with a school project. I'm building a light dimmer circuit with the use of microcontrollers; specifically using the PIC 18M2 to control the dimming of the light bulb. With 18M2, I am using a pwm code which can vary the voltage depending on a readadc input voltage. The code works perfectly but I would like to use a 7V filament bulb (so I can vary the voltage from 1-7V) as the output however the maximum voltage rating of the 18M2 is 4.5V. I was thinking about using a MOSFET to amplify this voltage but I'm not sure on how to do it. Does anyone know of anyway that this could be completed?

    Thanks
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    are you doing a DC PWM with a mosfet to control the bulb?
     
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    You need a mosfet that will switch at "logic level", several amps of current handling capability and low gate capacitance.

    image.jpg
     
  4. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    likely bolted to a heatsink.
     
  5. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    I've been using these lately. They laugh at 1 or 2 amps. SMDs with 15 mohms on resistance. No heat sink needed with reasonable switching speeds and Pwm frequency.

    http://www.vishay.com/docs/66587/si4666dy.pdf
     
    MikeML likes this.
  6. markodaguy

    Thread Starter New Member

    Mar 24, 2015
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    Yeah, that's what I'd like to achieve lol
     
  7. markodaguy

    Thread Starter New Member

    Mar 24, 2015
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    Thanks, do you have examples of such mosfets?
     
  8. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Irf640, mosfet, will do the job, there are others too..
     
  9. MaxHeadRoom

    Expert

    Jul 18, 2013
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    You would need the logic version, IRL640.;)
    Max.
     
  10. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    See post 5 if you are able to make a board and solder surface mount components.

    Otherwise, use the irl640 that max suggested in post 9
     
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