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How to create a temperature controller for a CPU cooling fan (or similar cooling fan for other electronics) only a few bucks and a handful of parts.

Build yourself a fan temperature control [via]

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of a dozen books on technology, DIY, and geek culture, including the first book about the web (Mosaic Quick Tour) and the Absolute Beginner’s Guide to Building Robots. He is currently working on a best-of collection of his writing, called Borg Like Me.



  1. Michael Covington says:

    The MOSFET dissipates no heat when it is fully “off” or “on.” However, in theory, there is a temperature at which the MOSFET will be “half on” and will dissipate heat. How much current does the fan draw under that condition? Is a heat sink needed?

  2. Don Hersey says:

    Yup, Michael C, you are correctly alluding to a weakness in this design. Properly realized, this circuit would include a comparator (w/hysteresis) to make sure the mosfet is truly switched. mosfets have a great deal of process spread, so this is not a ‘good circuit.’
    Without wanting to come off as a latent jerk, it wouldn’t kill a person to read a few books on electronic design. Fairchild’s op amp hand book, the Art of Electronics, ARRL pubs, something!